| 1. |
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| 2. |
- Al-Rawi, Ali, 1985, et al.
(författare)
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A new compact wideband MIMO antenna – the double-sided tapered self-grounded monopole array
- 2014
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:6, s. 3365 - 3369
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Tidskriftsartikel (refereegranskat)abstract
- We present a new compact wideband multiple input multiple output (MIMO) antenna—the double-sided 4-port arm-tapered self-grounded monopole array, briefly referred to as the butterfly antenna, in the communication. The antenna is very compact with low correlation between ports and high diversity gain. The genetic algorithm optimization scheme has been employed in the design. Simulation results have been verified against measurements. The measured reflection coefficients at all ports are below -7 dB over 0.5–9 GHz and below -4.5 dB over 0.4–0.5 GHz and 9–15 GHz. The measured correlation coefficients are below 0.4 over 0.4–15 GHz and lower than 0.1 in most of the frequency band. This new MIMO antenna is developed as a transmit antenna in reverberation chambers, and we believe that it will find more applications in other systems, such as micro base station antennas in wireless communication systems.
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| 3. |
- Alayon Glazunov, Andres, et al.
(författare)
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Impact of Scattering Within a Multipath Simulator Antenna Array on the Ricean Fading Distribution Parameters in OTA Testing
- 2014
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:6, s. 3257-3269
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the unwanted scattering that exists within the multipath simulator (MPS) array antennas employed in over the air (OTA) testing of mobile terminals. The impact of scattering is evaluated in terms of the measurement uncertainty of the average received power and the Ricean K-factor. The maximum ratio combining diversity is investigated for a generic device under test comprising two half-wavelength dipole antennas. We provide closed-form expressions for the uncertainties of the average received power and the Ricean K-factor for a uniform circular array of MPS antennas and a 2-D uniformly distributed angle-of-arrival spectrum. We also derive the maximum number of MPS antennas and the minimum ring radius of the MPS system as a function of the separation between the most distant antenna elements if the device under test employs a uniform linear array. As a result, we provide design guidelines for MPS array in terms of the number antennas, the radius of the MPS array and the wavelength of the carrier frequency.
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| 4. |
- Alayon Glazunov, Andres, et al.
(författare)
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On the Physical Limitations of the Interaction of a Spherical Aperture and a Random Field
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 59:1, s. 119-128
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Tidskriftsartikel (refereegranskat)abstract
- This paper derives physical limitations on the interactions of antennas exciting TM or TE modes (but not both) and wireless propagation channels. The derivation is based on the spherical vector wave expansion of the electromagnetic field outside a sphere circumscribing the antennas. The result is an extension of the seminal work of Chu on the classical limitations on maximum antenna gain and radiation Q. Rather than maximizing antenna gain in a single direction we obtain physical limitations on the antenna gain pattern, which is directly translated to more condensed parameters, i.e., the instantaneous effective gain G(i) and the mean effective gain G(e) if instantaneous realizations or correlation statistics of the expansion coefficients of the electromagnetic field are known, spectively. The obtained limitations are on the maximum of G(i)/Q and G(e)/Q, which establish a trade-off between link gain and Q.
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| 5. |
- Alayon Glazunov, Andres, et al.
(författare)
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Spherical Vector Wave Expansion of Gaussian Electromagnetic Fields for Antenna-Channel Interaction Analysis
- 2009
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:7, s. 2055-2067
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we introduce an approach to analyze the interaction between antennas and the propagation channel. We study both the antennas and the propagation channel by means of the spherical vector wave mode expansion of the electromagnetic field. Then we use the expansion coefficients to study some properties of general antennas in thosefields by means of the antenna scattering matrix. The focus is on the spatio-polar characterization of antennas, channels and their interactions. We provide closed form expressions for the covariance of the field multimodes as function of the power angle spectrum (PAS) and the channel cross-polarization ratio (XPR). A new interpretation of the mean effective gains (MEG) of antennas is also provided. The maximum MEG is obtained by conjugate mode matching between the antennas and the channel; we also prove the (intuitive) results that the optimum decorrelation of the antenna signals is obtained by the excitation of orthogonal spherical vector modes.
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| 6. |
- Alex-Amor, Antonio, et al.
(författare)
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Dispersion Analysis of Periodic Structures in Anisotropic Media : Application to Liquid Crystals
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 70:4, s. 2811-2821
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an efficient method to compute the dispersion diagram of periodic and uniform structures with generic anisotropic media. The method takes advantage of the ability of full-wave commercial simulators to deal with finite structures having anisotropic media. In particular, the proposed method extends the possibilities of commercial eigenmode solvers in the following ways: 1) anisotropic materials with nondiagonal permittivity and permeability tensors can be analyzed; 2) the attenuation constant can easily be computed in both propagating and stopband regions, and lossy materials can be included in the simulation; and 3) unbounded and radiating structures, such as leaky-wave antennas (LWAs), can be treated. The latter feature may be considered the most remarkable since the structures must be forcefully bounded with electric/magnetic walls in the eigensolvers of most commercial simulators. In this work, the proposed method is particularized for the study of liquid crystals (LCs) in microwave and antenna devices. Thus, the dispersion properties of a great variety of LC-based configurations are analyzed, from canonical structures, such as waveguide and microstrip, to complex reconfigurable phase shifters in ridge gap-waveguide technology and LWAs. Our results have been validated with previously reported works in the literature and with commercial software CST and HFSS.
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| 7. |
- Alibakhshikenari, Mohammad, et al.
(författare)
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Dual-Polarized Highly Folded Bowtie Antenna with Slotted Self-Grounded Structure for Sub-6 GHz 5G Applications
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:4, s. 3028-3033
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel dual-polarized highly-folded self-grounded Bowtie antenna that is excited through I-shaped slots is proposed for applications in sub-6GHz 5G multiple-input-multiple-output (MIMO) antenna systems. The antenna consists of two pairs of folded radiation petals whose base is embedded in a double layer of FR-4 substrate with a common ground-plane which is sandwiched between the two substrate layers. The ground-plane is defected with two I-shaped slots located under the radiation elements. Each pair of radiation elements are excited through a microstrip line on the top layer with RF signal that is 180° out of phase with respect to each other. The RF signal is coupled to the pair of feedlines on the top layer through the I-shaped slots from the two microstrip feedlines on the underside of the second substrate. The proposed feed mechanism gets rid of the otherwise bulky balun. The Bowtie antenna is a compact solution with dimensions of 32 32 33.8 mm3. Measured results have verified that the antenna operates over a frequency range of 3.1–5 GHz and exhibits an average gain and antenna efficiency in the vertical and horizontal polarizations of 7.5 dBi and 82.6%, respectively.
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| 8. |
- Amani, Navid, 1985, et al.
(författare)
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Sparse Array Synthesis Including Mutual Coupling for MU-MIMO Average Capacity Maximization
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; In Press, s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid optimization algorithm including mutual coupling (MC) is proposed to synthesize an irregular sparse array (ISA) for average capacity maximization in a multi-user multiple-input multiple-output (MU-MIMO) system. The hybrid approach is composed of two phases to sub-optimally determine the location of a fixed number of omni-directional thin dipole antennas in an arbitrary sparse aperture via a diagonal antenna selection matrix. In Phase I, the problem is relaxed to a convex optimization by ignoring the MC and weakening the constraints. The output of Phase I is accounted as a reliable initial guess for the genetic algorithm (GA) in Phase II, which incorporates the MC effects through the coupling matrix and avoids the convex relaxation technique. The proposed approach outperforms the conventional GA with a random initial population, while it avoids trying several starting positions. Meanwhile, the undesirable appearance of grating lobes, due to the under-sampling, and the degrading MC effects are suppressed by aperiodicity. It is observed that, doubling the conventional inter-element spacing (half-wavelength) and finding the location of eight dipoles in a sparse aperture by the proposed method improves the average capacity by 3.27-11.9% when the number of users varies from two to eight and the signal-to-noise ratio (SNR) is 30dB.
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| 9. |
- Amjad, Iqbal, Universitetslektor, 1994-, et al.
(författare)
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Simultaneous Transmit and Receive Self-Duplexing Antenna for Head Implants
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:11, s. 8592-8601
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Tidskriftsartikel (refereegranskat)abstract
- A novel dual-port, dual-band self-duplexing implantable antenna for head implants is presented in this article. It operates at 915 MHz Industrial, Scientific, and Medical (ISM) band (when Port 1 is active) and 1420 MHz Wireless Medical Telemetry Service (WMTS) band (when Port2 is active). The proposed antenna is kept inside a flat device and simulated in a human head model. The miniaturization of the proposed antenna is achieved using a high dielectric substrate, shorted pins, and multiple capacitive slots. Consequently, it occupies a compact volume of 7.13 x 8.9 x 0.13 = 8.24 mm(3). The coupling between both radiators is enhanced by printing it on a thin substrate and placing vias between them. As a result, an isolation level better than 31.4 dB is achieved. It has peak realized gains of -18.94 and -17.06 dBi at 915 and 1420 MHz, respectively. The link budget analysis and specific absorption rate (SAR) are performed, showing promising results. The proposed concept is practically validated by measuring its performance inside the minced pork meat. Furthermore, the simultaneous transmit and receive concept is practically verified with the aid of software-defined radio (SDR). The main advantages of this antenna are its compact size, low coupling level, independently controllable bands, and simultaneous transmission and reception of signals without using a multiplexer circuit. © 2023 IEEE.
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| 10. |
- Atia Abdalmalak, Kerlos, et al.
(författare)
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Ultrawideband Conical Log-Spiral Circularly Polarized Feed for Radio Astronomy
- 2020
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 68:3, s. 1995-2007
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Tidskriftsartikel (refereegranskat)abstract
- In order to meet the requirements of the new generation of radio telescopes, we have developed a new topology called DYQSA, which stands for DYson Quad-Spiral Array. The design exhibits dual circular polarization contrary to dual linear polarization of state-of-the-art feeds. It covers the required ultrawideband (UWB) from 2 to 14 GHz with an almost constant and real input impedance which facilitates the design of the feeding structure and the low-noise amplifiers (LNAs). Different versions are investigated for enhancing feed performance, ensuring higher aperture efficiencies and mechanical stability. The simulation results of the reflector loaded by the proposed feed show an aperture efficiency of 65%±5% with a noise antenna temperature around 14 K and a system equivalent flux density (SEFD) of about 1300 Jy, both averaged over the required bandwidth at zenith. Measurements of the single-element and the four-element feeds are presented. Comparisons with other state-of-the-art feeds are shown in terms of total aperture efficiencies, design adaptability to different reflectors, calibration signal injection, and the required number of LNAs per feed, cost, and physical volume.
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| 11. |
- Bagheri, Alireza, et al.
(författare)
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A 16 × 16 45° Slant-Polarized Gapwaveguide Phased Array With 65-dBm EIRP at 28 GHz
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:2, s. 1319-1329
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Tidskriftsartikel (refereegranskat)abstract
- A high equivalent isotropic radiated power (EIRP) active phased array antenna is proposed for fifth-generation (5G) communication systems at 28 GHz. The numerical design, measurements of a fabricated prototype, and performance analysis are presented. The antenna design is based on the gapwaveguide technology and consists of $16 \times 16$ single 45° slant-polarized elements. The proposed design uses a low complexity printed circuit board (PCB) structure with only six layers, i.e., a half of the existing wideband solutions. The array antenna incorporates up/downconverter integrated circuits (UDCs) and $1 \times 4$ transceiver beamformer integrated circuits (BFICs). Moreover, a compact and highly efficient transition at the end of each channel of the BFICs has been designed to interconnect the antenna elements with the PCB. The antenna's front-end loss, which includes the feed line, mismatch, and ohmic losses, is only 1.3 dB. The array covers the scanning range of ±60° in the azimuth plane and ±10° in the elevation plane. The $S_{11} < -10$ dB frequency bandwidth is from 26.5 to 29.5 GHz. The maximum EIRP of the antenna is 65.5 dBm at saturation point. The presented design offers a compact, robust, and low-loss performance solution meeting the high transmission power requirements of 5G applications.
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| 12. |
- Bantavis, P. I., et al.
(författare)
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A Cost-Effective Wideband Switched Beam Antenna System for a Small Cell Base Station
- 2018
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-926X .- 1558-2221. ; 66:12, s. 6851-6861
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Tidskriftsartikel (refereegranskat)abstract
- A wideband switched beam antenna array system operating from 2 to 5 GHz is presented. It is comprised of a 4 × 1 Vivaldi antenna elements and a 4 × 4 Butler matrix beamformer driven by a digitally controlled double-pole four-throw RF switch. The Butler matrix is implemented on a multilayer structure, using 90° hybrid couplers and 45° phase shifters. For the design of the coupler and phase shifter, we propose a unified methodology applied, but not limited, to elliptically shaped geometries. The multilayer realization enables us to avoid microstrip crossing and supports wideband operation of the beamforming network. To realize the Butler matrix, we introduce a step-by-step and stage-by-stage design methodology that enables accurate balance of the output weights at the antenna ports to achieve a stable beamforming performance. In this paper, we use a Vivaldi antenna element in a linear four-element array, since such element supports wideband and wide-scan angle operation. A soft condition in the form of corrugations is implemented around the periphery of the array, in order to reduce the edge effects. This technique improved the gain, the sidelobes, and helped to obtain back radiation suppression. Finally, impedance loading was also utilized in the two edge elements of the array to improve the active impedance. The proposed system of the Butler matrix in conjunction with the constructed array can be utilized as a common RF front end in a wideband air interface for a small cell 5G application and beyond as it is capable to simultaneously cover all the commercial bands from 2 to 5 GHz.
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| 13. |
- Bencivenni, Carlo, 1986, et al.
(författare)
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Synthesis of Maximally Sparse Arrays Using Compressive Sensing and Full-Wave Analysis for Global Earth Coverage Applications
- 2016
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 64:11, s. 4872-4877
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Tidskriftsartikel (refereegranskat)abstract
- Global optimization methods can be employed to design aperiodic array antennas that accurately account for their electromagnetic (EM) behavior and complex performance specifications. However, they are computationally expensive and, therefore, limited to small to midsized array problems. On the other hand, analytical methods do not suffer from this problem, but often assume idealized antenna elements and fully adjustable excitation controls, thereby excluding beam degradation effects caused, e.g., by mutual coupling (MC) and quantized phase shifters. We present a fast design method for large maximally sparse arrays that is capable of handling the aforementioned limitations. It is based on the previously published combined EM-Compressive Sensing approach, which has been herein generalized for multibeam optimization, and where we also exploit array symmetry in order to reduce the design complexity. Results are obtained for a circular array ( 100 λ diameter) of horn antennas operating in a multibeam SATCOM scenario, and demonstrate that even weak MC effects and small phase quantization are important when very demanding sidelobe and cross-polarization levels are required.
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| 14. |
- Beukman, T. S., et al.
(författare)
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Modal-Based Design of a Wideband Quadruple-Ridged Flared Horn Antenna
- 2016
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 64:5, s. 1615-1626
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a systematic design technique for quadruple-ridged flared horn antennas is presented, to enhance the radiation properties through the profiling of the ridge taper. The technique relies on control of the cutoff frequencies of specific modes inside the horn, instead of brute-force optimization. This is used to design a prototype antenna as a feed for an offset Gregorian reflector system, such as considered for the Square Kilometer Array (SKA) radio telescope, to achieve an optimized aperture efficiency from 2 to 12 GHz. The antenna is employed with a quadraxial feeding network that allows the excitation of the fundamental TE11 mode, while suppressing all other modes that causes phase errors in the aperture. Measured results confirm the validity of this approach, where good agreement is found with the simulated results.
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| 15. |
- Borg, Johan, et al.
(författare)
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Delay insensitive signal-injection calibration for large antenna arrays using passive hierarchical networks
- 2017
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Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 65:1, s. 190-195
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Tidskriftsartikel (refereegranskat)abstract
- Efficient beamforming of phased-array antennas requires that the phase delay of each channel is accurately known. One technique for achieving this is to distribute a calibration or local-oscillator reference signal through a delay-insensitive signal distribution network. In this paper, we propose using passive hierarchical signal distribution networks to distribute such signals, a method that scales significantly better with the size of the array than existing signal distribution methods. We analyze the impact of impedance variations within the network on the phase accuracy and propose a calibration front-end architecture. This front end also enables the return loss and coupling between antennas to be monitored for diagnostic purposes. We present an implementation of this front end that was applied to a small prototype antenna array, and show that this implementation exhibited low sensitivity to delays within the calibration network, reduced the temperature-dependent phase error of the front ends substantially, and can be used for performing antenna return-loss measurements
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| 16. |
- Bosiljevac, Marko, et al.
(författare)
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Efficient Analysis of Aperture Antennas on Generally Shaped Convex Multilayered Surfaces Using a Hybrid SD-UTD Method
- 2009
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:5, s. 1420-1431
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Tidskriftsartikel (refereegranskat)abstract
- A novel hybrid method is described for analyzing convex multilayered conformal array antennas. The hybrid method is based on the spectral domain approach in combination with the ray-based uniform theory of diffraction (UTD) method. The analysis is divided in two parts. First, the spectral domain approach is accelerated by using an asymptotic extraction technique where the extracted term of the Green's function is calculated using UTD. It is shown that this new approach results in significant acceleration of the existing spectral domain algorithm without losing accuracy. The modified spectral domain method is then used in the second part where generally shaped convex multilayered surfaces are analyzed by using sets of canonically shaped surfaces (spheres and/or circular cylinders). Their radii are obtained using the UTD formulation, which contains important information such as distance and curvature of the generally shaped surface along each geodesic. The results obtained using the new algorithm are compared to the available results (calculated and measured) for different conformal antennas, showing very good agreement.
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| 17. |
- Bosiljevac, M., et al.
(författare)
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Simple Boundary Condition for Canonical EBG Surface: PMC-Backed Uniaxial Medium
- 2016
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 64:2, s. 785-U550
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Tidskriftsartikel (refereegranskat)abstract
- A simple-to-use replacement model for isotropic electromagnetic bandgap (EBG) surfaces such as mushroom surfaces is investigated. Properties of EBG surfaces strongly depend on the incidence angle of the incoming plane wave. The suggested model takes this behavior into account and actually represents the ideal EBG surface. The model is based on uniaxial representation of a thin DB layer backed by a perfect magnetic conductor (PMC) plate. We investigate how this model behaves in comparison with a realistic mushroom surface, and when it can be applied. The results show that the proposed model can be used for both far field calculations and antenna coupling evaluation.
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| 18. |
- Braun, Christian, et al.
(författare)
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Evaluation of antenna diversity performance for mobile handsets using 3-D measurement data
- 1999
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 47:11, s. 1736-1738
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Tidskriftsartikel (refereegranskat)abstract
- An evaluation of two-branch antenna diversity on mobile telephones is performed in the presence of head and hand phantoms to model the influence of the user. Two mobile telephone prototypes for the 1800-MHz band are considered. The evaluation is done by measuring the three-dimensional (3-D) complex radiation patterns from each antenna with the prototypes positioned near the phantom head and hand (i.e., in talk position) and calculating the diversity performance for three different scenarios of the incoming field. The two-branch antenna setups on both prototypes produce a calculated diversity gain of about 9 dB for selection diversity at the 99% reliability level.
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| 19. |
- Buck, David, et al.
(författare)
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Measuring Array Mutual Impedances Using Embedded Element Patterns
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:1, s. 606-611
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Tidskriftsartikel (refereegranskat)abstract
- The radiation pattern of an antenna element embedded in a multiport antenna such as a phased array depends on the loads connected to the array element ports. If the embedded element patterns are measured using at least two known loading conditions, the patterns can be used to determine the array mutual impedance matrix. In previous work, this result has been derived with the simplifying assumption that the impedance of the source connected to the driven element changes along with the load impedances connected to the nondriven elements. In a practical test configuration, the source impedance cannot be readily changed. We analyze the case of EEPs measured with a fixed source impedance and changing impedances on the nondriven elements. The transformation from one set of EEPs to another with fixed source impedance is more complex than in the case of a source impedance that changes with the load impedances. The transformation depends on the coupling between elements and is only weakly sensitive to the element self-impedances. With measured EEPs for an array of identical elements, the impedance matrix can be found up to a scale factor. We demonstrate the method experimentally by measuring the patterns of an antenna array terminated with one loading condition and repeating the pattern measurements with a different loading condition. The mutual impedance matrix extracted from the pattern measurements compared to network analyzer mutual impedance measurements is accurate to within 1–2 Ω for most of the mutual impedances.
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| 20. |
- Carozzi, Tobia, 1966, et al.
(författare)
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A Fundamental Figure of Merit for Radio Polarimeters
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 59:6, s. 2058-2065
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Tidskriftsartikel (refereegranskat)abstract
- Many modern radio applications, such as astronomy and remote sensing, require high-precision polarimetry. These applications put exacting demands on radio polarimeters (antenna systems that can measure the state of polarization of radio sources), and in order to assess their polarimetric performance, a figure of merit (FoM) would be desirable. Unfortunately, we find that the parameter commonly used for this purpose, the cross-polarization ratio, is not suitable as a polarimetry FoM unless it is given in an appropriate coordinate system. This is because although the cross-polarization ratio is relevant for raw, uncalibrated polarimetry, in general it is not relevant to the quality of the polarimetry after polarimetric calibration. However, a cross-polarization ratio can be constructed from invariants of the Jones matrix (the matrix that describes the polarimetric response of a polarimeter) that quantifies polarimetric performance even after calibration. We call this cross-polarization ratio the intrinsic cross-polarization ratio (IXR) and conclude that it is a fundamental FoM for polarimeters. We then extend the IXR concept from the Jones calculus to the Mueller calculus and also to interferometers, and we give numerical examples of these parameters applied to the Parkes radio telescope, the Westerbork synthesis radio telescope, and the Effelsberg telescope.
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| 21. |
- Castillo Tapia, Pilar, et al.
(författare)
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Two-Dimensional Beam Steering Using a Stacked Modulated Geodesic Luneburg Lens Array Antenna for 5G and Beyond
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:1, s. 487-496
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Tidskriftsartikel (refereegranskat)abstract
- Antennas for future communication systems are required to be highly directive and steerable to compensate for the high path loss in the millimeter-wave band. In this work, we propose a linear array of modulated geodesic Luneburg lens (the so-called water drop lens) antennas operating at 56-62 GHz. The lens array antenna features 2-D beam scanning with low structural complexity. The lenses are fully metallic and implemented in parallel plate waveguides (PPWs), meaning that they are highly efficient. Each lens is fed with 13 rectangular waveguides surrounded by glide-symmetric holes to suppress leakage. The lenses provide 110? beam coverage in the H-plane with scan losses below 1 dB. In order to scan in the E-plane, we use a feeding network based on a 1:4 power divider and three phase shifters. In this configuration, the array can scan 60? in the E-plane, albeit with higher scanning losses than in the H-plane. The lens array is manufactured and a good agreement between simulated and experimental results is obtained.
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| 22. |
- Chen, Ming Zheng, et al.
(författare)
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Geodesic H-Plane Horn Antennas
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:8, s. 6329-6339
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Tidskriftsartikel (refereegranskat)abstract
- This article describes a detailed procedure that allows for a time-efficient design of fully metallic geodesic H-plane horn antennas using an in-house ray-tracing method together with an optimization algorithm. With all the propagation in the air, geodesic H-plane horn antennas are of low loss and highly efficient. The proposed geodesic H-plane horn antennas provide a new degree of freedom, the height profile, to alleviate phase errors, realizing high gains and aperture efficiencies. Optimizations are implemented to design the height profile for a given target, enabled by the highly accurate and time-efficient in-house ray-tracing model. To demonstrate the correctness and versatility of the proposed design procedure, two prototypes are manufactured with computerized numerical control (CNC) machining and compared to their planar counterparts, with the aim of a high increased gain and aperture efficiency, respectively. The prototypes maintain good frequency stability from 26 to 33GHz, with sidelobe levels lower than -15dB and return loss better than 15dB. The first prototype improves the realized gain by over 5dB compared to the reference horn, while the second prototype achieves an aperture efficiency of around 65% within the operating frequency band.
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| 23. |
- Chen, Ming Zheng, et al.
(författare)
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Ray-Tracing and Physical-Optics Model for Planar Mikaelian Lens Antennas
- 2024
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 72:2, s. 1735-1744
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Tidskriftsartikel (refereegranskat)abstract
- This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides (PPWs). With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristics, the planar Mikaelian lens antennas are easy to fabricate and integrate into standard planar feeds. A numerical computation of the ray paths based on Snell's law describes the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far-field of the lens antenna. The information on far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and a significant reduction in computation resources and times.
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| 24. |
- Chen, Qiao, et al.
(författare)
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Efficient Leaky-Lens Antenna at 60 GHz Based on a Substrate-Integrated-Holey Metasurface
- 2020
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 68:12, s. 7777-7784
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a low-cost implementation of a low-dispersive leaky-wave antenna (LWA) at 60 GHz for point-to-point 5G communications. The LWA is implemented with glide-symmetric holes in gap-waveguide technology. The radiation is produced through a slit and controlled with glide-symmetric holes. The low dispersion is achieved thanks to the use of a dispersive prism that compensates the frequency dependence of the radiation through the slit. The main innovation of our proposed design is the use of substrate integrated holes (SIHs) to implement the dispersive prism. This implementation significantly enhances the bandwidth and improves the robustness to manufacturing tolerances. Also, this implementation reduces the cost of the antenna while maintaining low losses since the majority of the propagation inside the prism is in air. Additionally, we demonstrate that the use of glide-symmetric holes in the slit allows for a better control of the amount of radiation (attenuation constant) when compared with conventional holes. The differences in the attenuation constant between conventional and glide-symmetric holes have been studied with a multimodal analysis. Apart from giving a convenient physical insight, this method also expedites the design process.
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| 25. |
- Chen, Qiao, et al.
(författare)
-
Glide-Symmetric Holey Leaky-Wave Antenna With Low Dispersion for 60 GHz Point-to-Point Communications
- 2020
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 68:3, s. 1925-1936
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, two novel efficient leaky-wave antennas (LWAs) with stable radiation patterns operating in the 60 GHz band are proposed. The LWAs are implemented in groove-gap waveguide (GGW) technology. To mitigate the beam squint due to the dispersive nature of LWAs, complementary-dispersive prisms are coupled to the LWA radiation aperture. The antennas are implemented in fully metallic purely holey periodic structures, resulting in a more cost-effective and robust manufacturing process compared to previously reported pin-based structures. Two prisms are proposed, one with mirror symmetry and one with glide symmetry. When the prism possesses a glide symmetry, much fewer holes are required while maintaining a similar performance, which even further decreases the fabrication costs. The complex propagation constant is optimized for low sidelobe levels (SLLs) with tailored hole diameters and waveguide dimensions, thus for the first time demonstrating the capability of using glide-symmetric holes to control the leakage rate. Two prototypes with mirror- and glide-symmetric prisms are theoretically synthesized and validated by the simulated and experimental results. A frequency bandwidth of 11% is achieved for both prototypes with the beam squint within +/- 0.9 degrees (mirror) and +/- 1.7 degrees (glide), SLLs below -15 dB (mirror) and -13 dB (glide), total efficiency almost 90%, and realized gain of 17 +/- 0.5 dB at a fixed observing angle. The developed antennas are intended for mm-wave point-to-point communications.
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| 26. |
- Chen, Zihao, et al.
(författare)
-
A Multi-Port Microstrip Grid Array Structure
- 2016
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 64:11, s. 4953-4958
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a multi-port microstrip grid array structure, which gives the flexibility to use it as a single antenna or multiple antennas. To realize such a structure, the key challenges are impedance matching and port isolation. It is shown that impedance matching can be made with stepped-impedance lines and port isolation can be enhanced from the defected ground plane. A particular example of 145 radiating elements with 4 ports is implemented in RT/duroid 5880 substrate for 24-GHz applications. Simulated and measured results are compared, which verifies the design, analysis, and versatility of the structure.
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| 27. |
- Cheng, Shi, et al.
(författare)
-
79 GHz Slot Antennas Based on Substrate Integrated Waveguides (SIW) in a Flexible Printed Circuit Board
- 2009
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:1, s. 64-71
-
Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication and characterization of 79 GHz slot antennas based on substrate integrated waveguides (SIW) are presented in this paper. All the prototypes are fabricated in a polyimide flex foil using printed circuit board (PCB) fabrication processes. A novel concept is used to minimize the leakage losses of the SlWs at millimeter wave frequencies. Different losses in the SlWs are analyzed. SIW-based single slot antenna, longitudinal and four-by-four slot array antennas are numerically and experimentally studied. Measurements of the antennas show approximately 4.7%, 5.4% and 10.7% impedance bandwidth (S-11 = -10 dB) with 2.8 dBi, 6.0 dBi and 11.0 dBi maximum antenna gain around 79 GHz, respectively. The measured results are in good agreement with the numerical simulations.
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| 28. |
- Cheng, Shi, et al.
(författare)
-
Foldable and stretchable liquid metal planar inverted cone antenna
- 2009
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:12, s. 3765-3771
-
Tidskriftsartikel (refereegranskat)abstract
- A mechanically flexible planar inverted cone antenna (PICA) for ultrawideband (UWB) applications is presented. It can be both folded and stretched significantly without permanent damage or loss of electrical functionality. The antenna is manufactured with a process in which conductors are realized by injecting room temperature liquid metal alloy into micro-structured channels in an elastic dielectric material. The elastic dielectric material together with the liquid metal enables bending with a very small radius, twisting, and stretching along any direction. Port impedance and radiation characteristics of the non-stretched and stretched antenna are studied in simulations and experiments. The presented antenna has a return loss better than 10 dB within 3-11 GHz and a radiation efficiency of > 70% over 3-10 GHz, also when stretched. Tests verify that stretching up to 40% is possible with maintained electrical performance. The presented antenna is useful for example for body-worn antennas and in applications in harsh environments where mechanical flexibility helps improve durability.
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| 29. |
- Cooray, Vernon
(författare)
-
On the accuracy of several approximate theories used in quantifying the propagation effects on lightning generated electromagnetic fields
- 2008
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 56:7, s. 1960-1967
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of finitely conducting ground on the signature of lightning generated vertical electric fields at ground level was evaluated by numerical solution of Sommerfeld's integrals. Results are presented for distances between 10 m to 1 km from the lightning channel and for ground conductivities in the range of 0.01 and 0.001 S/m. The results obtained from the exact theory are compared with the predictions of several approximate theories available in the literature. Based on that comparison the limits of validity of these approximate theories are obtained.
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| 30. |
- Cooray, Vernon, et al.
(författare)
-
Pulse propagation along transmission lines in the presence of corona and their implication to lightning return strokes
- 2008
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 56:7, s. 1948-1959
-
Tidskriftsartikel (refereegranskat)abstract
- Transmission line equations in air in the presence of corona are derived. The analysis shows that the corona caused by a voltage or a current pulse propagating along a transmission line can be represented by a series of corona current sources distributed along the line. Corona has two effects on the voltage or current pulses propagating along a transmission line. First, it will clamp down the pulse amplitude at the front of the pulse to the corona threshold. Second, it will cause the portion of the pulse whose amplitude is larger than the corona threshold to travel with a speed less than the speed of light. The effects of corona on the voltage or current pulses propagating along a transmission line can also be evaluated by introducing a time varying capacitance and a conductance into the transmission line. If the time varying capacitance is assumed to be proportional to the ratio between the corona charge and the applied voltage then one requires both this and the time varying conductance to represent the corona effects more accurately. Analysis of the return stroke as a current pulse propagating along a transmission line undergoing corona shows that the corona effects may explain the reason why the measured return stroke speeds are considerably less than the speed of light. Moreover, based on the effects of corona, a physical justification for the concepts used in the current generation type return stroke models is provided.
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| 31. |
- Cuesta, F. S., et al.
(författare)
-
Planar Broadband Huygens' Metasurfaces for Wave Manipulations
- 2018
-
Ingår i: Ieee Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 66:12, s. 7117-7127
-
Tidskriftsartikel (refereegranskat)abstract
- Electrically thin and effectively 2-D material composites, metasurfaces, have been widely exploited for the manipulation of electromagnetic waves. For many applications, it is desired to transform incident waves of a specific frequency range keeping the metasurface invisible at other frequencies. Such a frequency-selective response can be achieved based on subwavelength Huygens' inclusions. However, their fabrication requires sophisticated processes due to the 3-D geometry. Here, we propose a planar Huygens' meta-atom with the goal to open a way to realize broadband invisible metasurfaces with topologies suitable for the conventional printed circuit board fabrication technology. We synthesize and analyze, both numerically and experimentally, three different metasurfaces capable of polarization and amplitude transformations of incident waves.
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| 32. |
- Dahlberg, Oskar, et al.
(författare)
-
Low-Dispersive Leaky-Wave Antennas for mmWave Point-to-Point High-Throughput Communications
- 2020
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 68:3, s. 1322-1331
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we present two efficient leaky-wave antennas (LWAs) with stable radiation pattern, operating at 60 GHz. Both antennas exhibit attractive properties such as significantly reduced beam-squint, low loss, low sidelobes, high directivity, and simple manufacturing. The beam-squint of conventional LWAs is reduced by refracting the leaked waves in a dispersive lens and the low sidelobe levels are achieved by tapering the leakage rate along the aperture. Since the antennas are implemented in groove gap waveguide technology, the losses are low. The two antennas are different in terms of their asymmetric/symmetric leakage tapering with respect to the broadside direction. Both designs are optimized for low sidelobes, but since symmetry is enforced in one, the resulting performance in terms of sidelobes is suboptimal. However, in the symmetric design, multiple stable beams can be obtained, simultaneously or independently. Twenty percent bandwidth is obtained with less than +/- 0.5 degrees beam-squint. In this frequency range, the gain is stable at 17 and 15 dBi for the asymmetric and symmetric designs, respectively. The designs are intended for point-to-point links in mmWave communication networks where low losses, directive beams, and low sidelobes are expected to be key features.
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| 33. |
- Djounidi, Justine, et al.
(författare)
-
Low-Profile Fully Metallic Multiple-Ridge Luneburg Lens Antenna
- 2024
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 72:6, s. 4852-4861
-
Tidskriftsartikel (refereegranskat)abstract
- The geodesic Luneburg lens has been revisited as a suitable solution for applications requiring directive beams in the millimeter waveband. Among its advantages, its rotational symmetry and high efficiency stand out. However, one of its drawbacks is the need for a certain height to produce the desired focusing properties of the lens. Here, we propose a low-profile solution based on rotationally symmetric ridges that mimic, similar to geodesic lenses, the effective refractive index of a Luneburg lens. Moreover, we show that both rectangular and trapezoidal ridges perform similarly, opening the possibility for other manufacturing techniques. We demonstrate this concept with a prototype that is fully metallic and provides a scanning range of +/- 62 degrees over a broadband of operation, from 24 to 34 GHz. In this prototype, the height of the lens is 18 times more compact than the original Rinehart-Luneburg lens, allowing the lens to be vertically stacked, which is beneficial, for example, for producing linear arrays. This technique could be used to produce other type of lenses.
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| 34. |
- Dommisse, William R., et al.
(författare)
-
Macro Basis Functions for Efficient Analysis of Thick Wires in the MoM
- 2024
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 72:7, s. 5865-5876
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a macro basis function (MBF) formulation for efficient method of moments (MoM) modelling of conducting wires with appreciable thickness. General surface formulations are prohibitively inefficient for electrically thin wires, while the typical exact-kernel, rooftop-basis, thin-wire MoM becomes wholly inaccurate for electrically thick cylinders. The MBF formulation bridges the gap between thin-wire MoM, and general conducting surface MoM formulations, by introducing circumferential variations and components beyond the standard rooftop basis functions. The MBFs are constructed upon a full-order, divergence-conforming, triangle element MoM discretization. Comprehensive junction and end-cap treatment, and tapered wire support, are natural features of the formulation. As with thin-wire MoM, degrees of freedom (DoFs) are purely proportional to the electrical length of the wire. Results demonstrate that the intermediate range of “thick wires” is analyzed with practically the same accuracy as general surface MoM, with significantly reduced DoFs.
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| 35. |
- Dong, Bin, 1984, et al.
(författare)
-
Optimization and Realization of Quadruple-ridge Flared Horn with New Spline-defined Profiles as a High-efficiency Feed over 4.6–24 GHz
- 2019
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:1, s. 585-590
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new optimization and realization of a quadruple-ridge flared horn (QRFH) as a feed for reflector antennas of the Square Kilometre Array (SKA) project. The QRFH has been numerically optimized by spline-defined profiles for both the ridges and the horn sidewall, with a conical cavity in the back-short for maximum aperture efficiency. The final aperture efficiency better than (for horizontal polarization) or around (for vertical polarization) 78% over 4.6–8 GHz, 70% over 8–15 GHz, 65% over 15–20 GHz and 60% over 20–24 GHz in the SKA offset-Gregorian dual-reflector antenna has been achieved. The realization of the horn has been carried out carefully by applying several new mechanical design solutions in order to guarantee the accurate positioning of the ridges, the feeding pins and a good electrical contact. The measured S11 is mostly better than -10 dB and the predicted aperture efficiency based on the measured far field patterns agrees well with the simulated result. System performance, such as the sensitivity and system noise temperature, are also estimated and presented.
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| 36. |
- Ebrahimpouri, Mahsa, et al.
(författare)
-
Bespoke Lenses Based on Quasi-Conformal Transformation Optics Technique
- 2017
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 65:5, s. 2256-2264
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a systematic method to design a quasioptimum lens profile based on quasi-conformal transformation optics technique for a given excitation is presented. This method is applied to a number of conventional antennas, such as an aperture and a log-spiral slot. In all these configurations, an increase of the directivity is observed. Furthermore, using this method, a quasi-optimum graded index lens for a broadband enhanced leaky slot excitation is designed and the results are compared with a hyperhemispherical lens with and without matching layers. Our proposed methodology demonstrates to be able to increase the directivity, to reduce the sidelobes and the cross polarization in a broad bandwidth from 20 to 70 GHz. Due to the continuously changed dielectric constant of the lens profile, reflections are also reduced considerably inside the lens.
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| 37. |
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| 38. |
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| 39. |
- Elgered, Gunnar, 1955
(författare)
-
TROPOSPHERIC WET PATH-DELAY MEASUREMENTS
- 1982
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 30:3, s. 502-505
-
Tidskriftsartikel (refereegranskat)
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| 40. |
- Ellgardt, Anders, 1978-
(författare)
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A Scan Blindness Model for Single-Polarized Tapered-Slot Arrays in Triangular Grids
- 2008
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 56:9, s. 2937-2942
-
Tidskriftsartikel (refereegranskat)abstract
- A simple model is presented that predicts scan blindness in the E-plane for single polarized tapered-slot arrays where the elements are positioned in a triangular grid. The blindness occurs when the phase progression along the dielectric substrates is equal to the phase progression of a leaky mode in the structure. A simple equation is presented that estimates the frequency at which the scan blindness occurs for a given angle in the E-plane. This equation is derived from a simple representation of the phased array antenna, but includes the dominant effect of this particular class of scan blindness. The method is shown to agree well with computed results obtained with two different numerical codes.
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| 41. |
- Ellgardt, Anders, 1978-, et al.
(författare)
-
A single polarized triangular grid tapered-slot array antenna
- 2009
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:9, s. 2599-2607
-
Tidskriftsartikel (refereegranskat)abstract
- A triangular grid single polarized tapered-slot array antenna for radar applications is studied. Compared with a rectangular grid an equilateral triangular grid allows a larger unit cell without any onset of grating lobes. Since single polarized tapered-slots in triangular grids support guided modes, which cause scan blindness, the increase in unit cell size is smaller than the optimal 15%. The design presented in the paper is capable of scan angles out to 60° from broadside in the E and H planes. To improve the match over the radar band a local minimum in the active reflection coefficient is positioned at the most critical scan direction, resulting in a reflection coefficient that is less than -12 dB in the X-band. To reduce the radar cross section for the cross-polarization an absorbing layer is positioned above the ground plane, which affects some of the guided modes that lead to scan blindnesses. An experimental antenna with 16×16 elements was built, and it was found that the H-plane performance for large scan angles for the finite antenna deviates more than expected from the infinite array approximation. Otherwise both mutual coupling measurements and embedded element patterns agrees well with the numerical results.
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| 42. |
- Elsakka, Amr, et al.
(författare)
-
A mm-Wave Phased-Array Fed Torus Reflector Antenna with ±30° Scan Range for Massive-MIMO Base-Station Applications
- 2022
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:5, s. 3398-3410
-
Tidskriftsartikel (refereegranskat)abstract
- A phased-array fed reflector antenna system is presented which can be used for mm-wave base station applications. The proposed system is designed to support massive-Multi-Input-Multi-Output (MIMO) scenarios within a wide coverage (±30°) in the azimuth plane and a limited coverage at the elevation plane. A design and characterization methodology has been established to optimize the system for the operation in various line-of-sight conditions by adopting the maximum-ratio-transmission (MRT) and zero-forcing (ZF) MIMO algorithms. A two-user MIMO case study has been considered for the evaluation of the key system performance metrics, i.e. the effective isotropic radiated power, power consumption, signal-to-noise-ratio (SNR), and signal-to-interference-plus-noise-ratio (SINR). This study demonstrates that the phased-array fed reflector concept has a major advantage over traditional direct-radiating phased array (DRPA) antennas to reduce energy consumption. In the present example, it requires 12–14 dB less transmitted power as compared to the MRT-beamformed DRPAs for the same SNR, and 26–27 dB less transmitted power relatively to ZF-beamformed DRPA systems for the same SINR. A prototype, employing a 55 cm diameter torus reflector and operating at 28 GHz-band, has been manufactured and tested. The measurement results agree well with simulations.
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| 43. |
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| 44. |
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| 45. |
- Emadeddin, Ahmad, et al.
(författare)
-
Wide Scan, Active K-Band, Direct-Integrated Phased Array for Efficient High-Power Tx-Generation
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:9, s. 7579-7584
-
Tidskriftsartikel (refereegranskat)abstract
- In this communication, we propose a new wide-scan active direct-integrated 1×5 phased array antenna (AIPAA) for mm-Wave applications. The AIPAA's unit-cell comprises three K-band miniaturized tapered slot elements, a GaN high electron mobility transistor (HEMT) as a power amplifier (PA), a stability circuit, an input matching network (M.N.), and biasing components. The tapered slot antenna element is reshaped so that its input impedance closely matches the optimal load impedance of the HEMT (Zopt = 6 + j38 Ω at 22 GHz), which enhances the system efficiency. The peak-integrated PAs' power-added efficiency (PAEp) is ≥ 56 % with ≤ 9% variation over scan coverage (g±50°) at 1.5 dB power backoff from P1dB. The peak AIPAA system power-added efficiency (PAEs) is 51% with a peak array radiation efficiency of 92%. The relative frequency bandwidth with PAEp above 25% is between 9% and 13% over the scan range. The proposed AIPAA demonstrates less than 0.9 and 1 dB scanloss over the scan coverage in terms of antenna array gain and PAs' power gain (Gp), respectively. The peak PA-integrated array gain and EIRP at P1dB of 24 dBi and 51 dBm are achieved, respectively. The proposed AIPAA's size is 18 × 58 × 17 mm3 with a cell of 9.2 × 6.5 × 1.8 mm3. The measurements are in good agreement with electromagnetic and circuit co-simulation results.
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| 46. |
- Escobar, Ana C., et al.
(författare)
-
Homogenization of Periodic Structures Using the Multimodal Transfer Matrix Method
- 2023
-
Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:6, s. 4976-4989
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a method for obtaining the constitutive parameters of periodic structures from the computation of their dispersion relation and average fields. The method uses the scattering parameters (S-parameters) of multiple Bloch modes of a single unit cell. The corresponding multimodal scattering matrix is obtained with a suitable general-purpose electromagnetic software. Further post-processing of this scattering matrix is then carried out, which allows for the computation of the dispersion relation of structures with realistic finite conductivity or made of lossy dielectrics, as well as the calculation of the attenuation constant and the retrieval of the impedance, permittivity, and permeability. The proposed method is applied to homogenize some systems of interest: an artificial electric plasma built with wires, a free-space matched left-handed metamaterial based on two laterally shifted split ring resonators, a high-permittivity artificial dielectric based on densely arranged square metal patches, and a μ -near-zero metamaterial made of metallic cubes embedded in a dielectric. The retrieved material parameters are found to accurately describe the scattering of finite samples of the corresponding homogenized structures. This research is limited to orthorhombic unit cells smaller than half the free-space wavelength to avoid diffracted beams. Besides, since only one propagation direction is considered, only the transverse components of constitutive parameters are retrieved.
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| 47. |
- Fan, Fangfang, 1981, et al.
(författare)
-
Bandwidth Investigation on Half-Height Pin in Ridge Gap Waveguide
- 2018
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:1, s. 100-108
-
Tidskriftsartikel (refereegranskat)abstract
- Gap waveguide is a promising transmission structure, especially for millimeter-wave (mmW) and terahertz applications. It does not require conductive connection between the upper and the lower plates, which makes this technology gain advantages over conventional rectangular waveguides and substrate integrated waveguides in an mmW and terahertz regime. Different fabrication methods for gap waveguides should be employed for different frequency bands applied, such as molding, milling, die forming, electrical discharge machining, microelectromechanical systems, and 3-D printing. Therefore, different pin forms used in gap waveguides are required to match the applied fabrication methods. In this paper, a new pin form, the half-height-pin form, in gap waveguides is proposed for reducing the fabrication cost, and its stopband characteristics are investigated and compared with the previous full-height pins in gap waveguides at the V -band. A device of a double-ridged gap waveguide with two 90° bends for verifying the stopband characteristic analysis of the new pin form has been designed and manufactured. The measured data confirm our analysis and simulations.
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| 48. |
- Fang, Mu, 1992, et al.
(författare)
-
1-Dimensional Wide Scanning Gap Waveguide Based Slot Array Antenna using Decoupling Technique for 100 GHz Applications
- 2024
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 72:4, s. 3438-3450
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a 1-dimenional wide scanning slot array antenna based on ridge gap waveguide (RGW), operating at a 100 GHz band. A novel half wall decoupling structure is proposed to reduce the mutual coupling and the reflection coefficient simultaneously, thus achieving a more stable active reflection coefficient (ARC) within the ±60° scanning range. At the same time, special attention has been given in retaining the embedded pattern suitable for wide scanning performance. An 8-element slot array antenna (8×8 slots) with two different feeding networks is fabricated and measured to verify the scanning performance. The prototype achieves 91% total efficiency while scanned up to 60° with 3 dB scanning loss. The measured results show good agreement with the simulations both for the reflection coefficient and radiation performance.
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| 49. |
- Farahbakhsh, Ali, 1984, et al.
(författare)
-
A mmWave Wideband Slot Array Antenna Based on Ridge Gap Waveguide With 30% Bandwidth
- 2018
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:2, s. 1008-1013
-
Tidskriftsartikel (refereegranskat)abstract
- A wideband 8 x 8 element slot antenna array based on ridge gap waveguide feeding network has been proposed for mmWave applications. The antenna subarray consists of four radiating slots which are excited by a groove gap cavity layer. Compared with previously published works, the proposed planar antenna array has quite wide impedance bandwidth. The antenna covers a wideband of 50-67.8 GHz with 30% impedance bandwidth (VSWR < 2). Also, the antenna has only 2.5 dB gain variation over the entire bandwidth which implies also good radiation characteristics for the proposed antenna. The maximum measured gain value is about 27.5 dBi with a total efficiency of 80% for the proposed antenna within the band of interest. With this performance, the proposed antenna array is a promising candidate for mmWave communication systems.
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| 50. |
- Ferrando-Rocher, Miguel, et al.
(författare)
-
8 x 8 Ka-Band Dual-Polarized Array Antenna Based on Gap Waveguide Technology
- 2019
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:7, s. 4579-4588
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes an 8 x 8 fully metallic high-efficiency dual-polarized array antenna working at the Ka-band, based on the gap waveguide (GW) concept. The radiating element is a circular aperture backed by two stacked cylindrical cavities, which are orthogonally fed to achieve a dual-polarized performance. Both feeding layers consist of a GW corporate network to reach all the cavities backing each radiating element. Cavities are naturally integrated within the bed of nails hosting grooves and ridges for the guiding electromagnetic (EM) field, leading to a low-profile dual-polarized array in the Ka-band. The experimental results present good agreement with simulations. The measured radiation patterns agree well with the simulation and the antenna provides an average gain over 27 dBi within its operating bandwidth (29.5-31 GHz).
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