| 1. |
- Abbas, Taimoor, et al.
(författare)
-
Measurement-Based Analysis: The Effect of Complementary Antennas and Diversity on Vehicle-to-Vehicle Communication
- 2013
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 12:1, s. 309-312
-
Tidskriftsartikel (refereegranskat)abstract
- In vehicle-to-vehicle (V2V) communication systems the antennas are prone to shadowing and the antenna gain is dissimilar even for same antenna elements if mounted at different positions on the car. This paper investigates the impact of antenna placement based on channel measurements performed with four omni-directional antennas mounted on the roof, bumper, windscreen and left-side mirror of the transmitter and receiver cars. Results suggest to use antennas with complementary characteristics, e.g., antennas on each side, mounted on the roof and bumper, to exploit diversity and decrease the effect of shadowing.
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| 2. |
- Alayon Glazunov, Andres
(författare)
-
Expansion of the Kronecker and Keyhole Channels Into Spherical Vector Wave Modes
- 2011
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 10, s. 1112-1115
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we provide additional results on the expansion of wireless channels into spherical vector wave multipole modes. We specialize our results to multiple-input-multiple-output (MIMO) channels with Kronecker-product structure of the correlation matrix: 1) the Kronecker channel, and 2) the Keyhole channel. We show that the Kronecker or Keyhole structure of the multimode channel matrix implies the corresponding structure in the MIMO channel matrix. Moreover, we show that the separability of the joint probability distribution functions of the angle of arrival (AoA) and the angle of departure (AoD), i.e., the independence between the AoAs and the AoDs for co- and cross-polarized components results in a Kronecker-product structure of the full-correlation matrix of the multimode matrix for both the Kronecker and the Keyhole channels.
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| 3. |
- Aliakbari Abar, Hanieh, et al.
(författare)
-
79 GHz multilayer series-fed patch antenna array with stacked micro-via loading
- 2022
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 21:10, s. 1990-1994
-
Tidskriftsartikel (refereegranskat)abstract
- A wideband compact series-fed patch subarray is proposed for 79 GHz multiple-input multiple-output (MIMO) radar. The proposed subarray is, for the first time, loaded with stacked micro-vias (SMVs). Two sets of patches in the subarray are fed 180-degrees out-of-phase. A low-cost, high-resolution multilayer PCB technology, called “Any-Layer PCB”, is used to implement the SMVs, which cannot be done by standard HDI PCB technology. Moreover, the technology supports small SMVs on different layers, hence thick machine-drilled vias can be avoided. For comparison, a series-fed patch subarray with no SMV loading is designed. It is shown that SMV loading facilitates a larger overlap of the impedance and gain bandwidths, leading to a larger operating bandwidth. The measured 10 dB impedance and 3 dB gain bandwidths are 15% and 9.6%, respectively. The sidelobe suppression is above 12.9 dB, and the maximum array gain is 12.67 dBi at 79.1 GHz. This subarray is suitable for MIMO radar, as its width is around 1/2-wavelength and the SMVs around it mitigate the crosstalk between the transmitting and receiving arrays.
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| 4. |
- Aliakbari Abar, Hanieh, et al.
(författare)
-
Low-band MIMO antenna for smartphones with robust performance to user interaction
- 2021
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 20:7, s. 1195-1199
-
Tidskriftsartikel (refereegranskat)abstract
- This letter proposes a two-port MIMO smartphone antenna for frequency bands below 1 GHz, which is robust to user effects. The design is achieved by first analyzing the characteristic modes of a chassis that includes the large screen. Two modes predicted to be less affected by the user than other commonly used modes are selected. The modal currents and near-fields of the two desired modes then guide the design: The monopole-like mode introduced by the screen is tuned to resonance using shorting pins and selectively excited using the center feed location. The non-resonant loop mode is selectively excited for the first time by four inductive feeds added along the longer sides of the chassis, with proper phase shifts provided by a feeding network. The proposed antenna features isolation of above 19 dB and envelope correlation coefficient of below 0.12 in the considered scenarios. The measured bandwidth is above 15% for both ports, and the average radiation efficiency is 2 dB and 4.57 dB higher for two user scenarios with respect to a reference design. Moreover, no adaptive matching is needed as the impedance matching is robust to the user hand/head.
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| 5. |
- Arias, Marvin R., et al.
(författare)
-
Clustering approach for geometrically based channel model in urban environments
- 2006
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 5, s. 290-293
-
Tidskriftsartikel (refereegranskat)abstract
- Advanced radio system designs have been proposed to overcome the radio channel caused by multipath effects in urban environments or even take advantage of it to achieve higher performance.. In this letter, we present a clustering approach to represent the power delay angle profiles (PDAPs) of the multipath components in urban environments. A cluster in an urban area originates from scattering points such as street apertures, large buildings, roof edges, or building corners. Unlike the previous geometrical models based only on single bounce reflection, our model represents the PDAPs by clusters plus background single bounce scatter components, i.e., waves that arrive at the receiver by double bounce at least. We present a numerical example for a typical outdoor scenario using the approach proposed for urban environments and including both temporal and spatial properties regarding path delay and angle-of-arrival (AOA).
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| 6. |
- Bach Andersen, Jørgen, et al.
(författare)
-
On closely coupled dipoles in a random field
- 2006
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 5:1, s. 73-75
-
Tidskriftsartikel (refereegranskat)abstract
- Reception of partially correlated fields by two closely coupled electrical dipoles is discussed as a function of load impedances and open-circuit correlations. Two local maxima of the power may be achieved for two different load impedances, but in those cases the output correlations are high. Choosing the loads to give zero output correlations is possible for almost any real-valued open-circuit correlation with a resulting reduction of received power or gain. However, the excess loss is only of the order 1.5 $ dB$ for a spacing as small as 0.05 wavelength.
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| 7. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Microwave S-parameter Characterization of an Antenna-Coupled Catadioptric Lens
- 2009
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 8, s. 1299-1301
-
Tidskriftsartikel (refereegranskat)abstract
- The focusing property of a bow-tie antenna coupled catadioptric lens is studied experimentally using a vector measurement setup. The results show that the lens-antenna provides short-range focusing. Furthermore, the return loss of the lens-antenna was determined numerically and confirmed experimentally from 1 GHz to 10 GHz. The lens-antenna provides 60% bandwidth (VSWR ≤ 2) centered at 6 GHz. Finally, the lens-antenna was employed to detect and locate buried objects and results are presented.
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| 8. |
- Bencivenni, Carlo, 1986, et al.
(författare)
-
Aperiodic Switched Array for Line-of-Sight MIMO Backhauling
- 2018
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 17:9, s. 1712-1716
-
Tidskriftsartikel (refereegranskat)abstract
- A switchable aperiodic array solution is proposed to increase the minimum channel capacity of a multiple-input-multiple-output (MIMO) backhauling system over an extended line-of-sight communication range. The objective is to propose a low-complexity design solution that is cost-effective in regard to the manufacturing, installation, and its design process. It is shown that by adding only one switch and one auxiliary antenna per base station, a 4 × 4 MIMO system can be realized that is capable of minimizing the capacity loss that both regular and aperiodic arrays suffer from as a function of the link distance.
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| 9. |
- Bencivenni, Carlo, 1986, et al.
(författare)
-
Design of Maximally Sparse Antenna Arrays in the Presence of Mutual Coupling
- 2015
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1548-5757 .- 1536-1225. ; 14, s. 159-162
-
Tidskriftsartikel (refereegranskat)abstract
- An optimization framework is proposed that combines electromagnetic field simulations with an iterative l(1)-norm minimization procedure to synthesize optimally sparse antenna arrays. The proposed approach overcomes the limitation of design methodologies that assume idealized antenna elements employing equal (isolated or isotropic) element patterns, as these yield suboptimal solutions when the antenna mutual coupling effects cannot be ignored. The latter is demonstrated for arrays of relatively strongly coupled dipole radiators.
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| 10. |
- Bernland, Anders, et al.
(författare)
-
Estimation of Spherical Wave Coefficients from 3D Positioner Channel Measurements
- 2012
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 11, s. 608-611
-
Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic vector spherical waves have been used recently to model antenna-channel interaction and the available degrees of freedom in MIMO systems. However, there are no previous accounts of a method to estimate spherical wave coefficients from channel measurements. One approach for this, using a 3D positioner, is presented and analyzed in this letter. Measurement results are presented and discussed. It is concluded that estimates based on randomly positioned measurements within a volume are less sensitive to noise than those based only on measurements on the surface.
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| 11. |
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| 12. |
- Castillo Tapia, Pilar, et al.
(författare)
-
V-Band Monolithic Additive-Manufactured Geodesic Lens Array Antenna
- 2023
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 22:10, s. 2527-2531
-
Tidskriftsartikel (refereegranskat)abstract
- Fully metallic geodesic lens antennas are popular for millimeter-wave band applications due to their simplicity, robustness, and low loss. Here, we report the experimental results of a geodesic lens array antenna, which was specifically designed to be additive-manufactured in one single piece using laser powder-bed fusion (LPBF). LPBF in aluminum alloy AlSi10Mg is able to produce high conductivity and relatively low surface roughness, so the antenna is highly directive and efficient. In addition, LPBF increases the robustness of the design since the lens array is monolithic, i.e., the risks associated with the assembly, including misalignments and undesired air gaps between pieces, are totally eliminated.
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| 13. |
- Chandra, Rohit, et al.
(författare)
-
An Analytical Link Loss Model for On-Body Propagation Around the Body Based on Elliptical Approximation of the Torso with Arms' Influence Included
- 2013
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 12, s. 528-531
-
Tidskriftsartikel (refereegranskat)abstract
- An analytical model for estimating the link loss for the on-body wave propagation around the torso is presented. The model is based on the attenuation of the creeping waves over an elliptical approximation of the human torso and includes the influence of the arms. The importance of including the arms’ effect for a proper estimation of the link loss is discussed. The model is validated by the full-wave electromagnetic simulations on a numerical phantom.
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| 14. |
- Chandra, Rohit, et al.
(författare)
-
Antennas and Propagation for In-Mouth Tongue Controlled Devices in Wireless Body Area Networks
- 2015
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 14, s. 1518-1521
-
Tidskriftsartikel (refereegranskat)abstract
- Tetraplegic patients have to depend upon someone else for moving the wheelchair or typing on a computer. One of the ways to make them independent is by using tongue-controlled in-mouth wireless devices. This letter presents antennas and propagation for such devices in 2.45 GHz ISM band. A monopole and a loop antenna suitable in size and performance is presented for such devices. The propagation link between the in-mouth antenna and an external antenna is measured by mimicking the use-case scenarios of such devices by placing an external antenna on a laptop, and on a chair. The link loss is found to be in the range of 55-75 dB depending upon the antenna type and the scenario. Using these values of the link loss, a reliable link can be established between the in-mouth device and the external device either mounted on a wheelchair or a computer.
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| 15. |
- Cheng, Shi, et al.
(författare)
-
Printed slot planar inverted cone antenna for ultrawideband applications
- 2008
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 7, s. 18-21
-
Tidskriftsartikel (refereegranskat)abstract
- A novel ultrawideband (UWB) printed wide-slot antenna is presented. The design is based on the planar inverted cone antenna (PICA), introduced by Suh. The presented design comprises PICA-like structures, etched from a double-layer substrate. Compared to the original PICA, it is lower in profile, more compact and maintains comparable performance. A prototype integrated in a printed circuit board and fed by a microstrip line is fabricated and measured. The results show that the proposed antenna provides at least 13:1 impedance bandwidth at 10-dB return loss.
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| 16. |
- Cheng, Shi, et al.
(författare)
-
Switched beam antenna based on RF MEMS SPDT switch on quartz substrate
- 2009
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 8, s. 383-386
-
Tidskriftsartikel (refereegranskat)abstract
- This letter demonstrates a 20-GHz radio frequency microelectromechanical system (RF MEMS)-based electrically switchable antenna on a quartz substrate. Two quasi-Yagi antenna elements are monolithically integrated with a single-pole double-throw (SPDT) MEMS switch router network on a 21 mm x 8 mm chip. Electrical beam steering between two opposite directions is achieved using capacitive MEMS SPDT switches in the router. Port impedance and radiation patterns are studied numerically and experimentally. Measured results show that the switched beam antenna features a 27% impedance bandwidth (S-11 = -10 dB), a gain of 4.6 dBi, and a front-to-back ratio of 14 dB at 20 GHz when the control voltage is applied to one of the switch pairs of the SPDT switch.
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| 17. |
- Cismasu, Marius, et al.
(författare)
-
Multiband Antenna Q Optimization using Stored Energy Expressions
- 2014
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 13, s. 646-649
-
Tidskriftsartikel (refereegranskat)abstract
- A method to compute antenna Q from a single frequency current distribution is applied to the optimization of multiband radiating structures. A genetic algorithm produces suboptimal structures in the sense of simultaneous multiband minimum Q. These structures model in a simplified manner common wireless communication devices. The comparison with the physical bounds for the considered situations shows that the suboptimal structures perform close to their limitations. Matching networks are designed using real component models with a commercial tool. These networks have less than three components and provide less than -6.5dB reflection coefficient magnitude in all considered bands. The results show that the single frequency Q estimation method may be useful for antenna design
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| 18. |
- Conway, G. A., et al.
(författare)
-
In Situ Measurement of UHF Wearable Antenna Radiation Efficiency Using a Reverberation Chamber
- 2008
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1548-5757 .- 1536-1225. ; 7, s. 271-274
-
Tidskriftsartikel (refereegranskat)abstract
- The radiation efficiency and resonance frequency of five compact antennas worn by nine individual test subjects was measured at 2.45 GHz in a reverberation chamber. The results show that, despite significant differences in body mass, wearable antenna radiation efficiency had a standard deviation less than 0.6 dB and the resonance frequency shift was less than 1% between test subjects. Variability in the radiation efficiency and resonance frequency shift between antennas was largely dependant on body tissue coupling which is related to both antenna geometry and radiation characteristics. The reverberation chamber measurements were validated using a synthetic tissue phantom and compared with results obtained in a spherical near field chamber and finite-difference time-domain (FDTD) simulation.
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| 19. |
- Du, Yijun, et al.
(författare)
-
Design of Sharp Roll-Off Band Notch with Fragment-Type Pattern Etched on UWB Antenna
- 2018
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 17:12, s. 2404-2408
-
Tidskriftsartikel (refereegranskat)abstract
- Fragment-type etch patterns are proposed and designed on ultra-wideband planar antenna to acquire sharp roll-off band notch. Multi-objective evolutionary algorithm is applied to achieve the optimization searching of the best fragment-type etch pattern by setting multiple objectives to acquire the exact notched band and challenge the roll-off criterion (ROC) of band notch. Efficiency of the design can be improved by properly presetting slits on the patch radiator. For demonstration, designs with different slit presetting are implemented and tested. With single slit preset, band notch of ROC=0.72 at the WLAN band ranging from 5.15 GHz to 5.85GHz is acquired.
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| 20. |
- Ebrahimpouri, Mahsa, et al.
(författare)
-
Experimental Validation of a Bespoke Lens for a Slot Log-Spiral Feed
- 2020
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 19:4, s. 557-560
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we experimentally validate the concept of bespoke lenses for the specific design of a log-spiral feed. Bespoke lenses are designed using the concept of quasi-conformal transformation optics (QCTO) to enhance the radiation properties for a given feeding. Our experimental results demonstrate that the antenna with its bespoke lens has higher gain, lower cross polarization, lower sidelobes, and lower axial ratio than that with a conventional hyperhemispherical lens.
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| 21. |
- Ebrahimpouri, Mahsa, et al.
(författare)
-
Ultrawideband Anisotropic Glide-Symmetric Metasurfaces
- 2019
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1536-1225 .- 1548-5757. ; 18:8, s. 1547-1551
-
Tidskriftsartikel (refereegranskat)abstract
- This letter presents a method to realize anisotropic two-dimensional designs with wideband operation. Glide symmetry has been proven to increase the bandwidth and equivalent refractive index of periodic structures. Here, two anisotropic glide-symmetric unit cells are proposed and characterized. Our simulated results prove that these unit cells follow the general behavior of periodic structures possessing glide symmetry. Moreover, we demonstrate that higher level of anisotropy can also be achieved by glide symmetry. Combining our proposed anisotropic glide-symmetric unit cell and transformation optics, a 30% compressed Luneburg lens is designed. The lens operates from 1 to 13 GHz.
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| 22. |
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| 23. |
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| 24. |
- Frid, Henrik
(författare)
-
Closed-Form Relation between the Scan Angle and Feed Position for Extended Hemispherical Lenses based on Ray-Tracing
- 2016
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - : IEEE Press. - 1536-1225 .- 1548-5757. ; 15, s. 1963-1966
-
Tidskriftsartikel (refereegranskat)abstract
- This letter presents a closed-form relation between the scan angle and feed position for extended hemispherical lenses. This relation is derived using ray tracing, and it is valid for both large and small scan angles, in excellent agreement with full-wave simulations. It is demonstrated that the relation is linear in the small-angle limit, and the effective focal length determining the scan angle is presented. It is also demonstrated that the scan angle only depends on the geometrical configuration, and that it is independent of the lens material. To demonstrate the applicability of this scan angle relation to the design of focal plane arrays (FPAs), we demonstrate that it can be used to determine the FPA spacing that results in -3-dB overlap between switched beams. A comparison with full-wave simulations of lenses with varying materials and FPA elements demonstrates a root-mean-square (rms) accuracy of 0.27 degrees for the scan angle estimation, and rms accuracy of 0.26 dB for the -3-dB overlap criterion between the central and adjacent beams. Finally, we present scaling rules, which show that the scan resolution is inversely proportional to the lens diameter, whereas the FPA spacing is independent of the total lens size.
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| 25. |
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| 26. |
- Gruden, Mathias, et al.
(författare)
-
Measurements and Simulations of Wave Propagation for Wireless Sensor Networks in Jet Engine Turbines
- 2011
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 10, s. 1139-1142
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, measurements and simulations of wave propagation inside a jet engine fan have been performed. The investigation was done using both EM simulations of different cases of propagation inside the engine and by measuring the corresponding cases inside a half-scale model of a jet engine fan. The average path loss was calculated, and the shapes of the fading distributions were extracted. The time between two consecutive fading dips was measured in the empirical part. Measurements were performed with engine speeds of both 30 and 60 rpm and were shown to be linearly scalable from 60 rpm to full speed of 10 000 rpm. The results showed an average path loss of about 55 dB. When scaling the measurements from 60 rpm to full-speed rotation of about 10 000 rpm, the fading was so severe that the time slot between consecutive fading dips was limited to 290 mu s.
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| 27. |
- Gupta, Nitish Kumar, et al.
(författare)
-
Singular Phase Characteristics of Electromagnetic Absorbers and a Framework for Low-RCS Target Detection
- 2023
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 22:1, s. 134-138
-
Tidskriftsartikel (refereegranskat)abstract
- We conceptualize, numerically validate, and experimentally demonstrate a scheme for distant line-of-sight detection of low-observable targets, such as those covered by metamaterial absorbers, by solely relying on their nontrivial phase characteristics. Relying upon the temporal coupled-mode theory (TCMT), first, we put forward a generalized description of open resonators where we identify the presence of a spectral inflection point in the phase response function as the signature of interest. Thereafter, a realistic phase response function has been modeled and analyzed by incorporating the propagation aspects as well as band-limited Gaussian noise. Change of curvature information owing to the resonant absorption is then ascertained from this involute phase response by developing an algorithm. For pragmatic scrutiny of our proposition, we design a singly resonant (at 12 GHz) wideband resistive sheet-based metamaterial absorber providing − 10 dB absorption across the X- and Ku-bands and employ its de-embedded scattering parameters to confirm the existence of inflection point around 12 GHz. As a final validation, the metamaterial absorber has been fabricated using ITO/PET sheets, and its phase characteristics have been measured in a pseudomonostatic configuration. The information regarding the presence of resonant absorption has been then ascertained by the algorithm extracted phase, thereby validating our proposition.
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| 28. |
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| 29. |
- Hallbjörner, Paul, et al.
(författare)
-
Broadband Space-Time Measurements in Reverberation Chamber Including Comparison With Real Environment
- 2009
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 8, s. 1111-1114
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial variations of the broadband time-domain impulse response in a reverberation chamber are studied experimentally. The goal is to introduce the technique as a means for characterizing reverberation chambers and to demonstrate typical results and the information that can be extracted. Similar measurements are performed in a lab room for comparison. The results provide new insights regarding the signal environment inside a reverberation chamber and how it compares to real-life environments. The minimum number of signal paths in the chamber is calculated based on the spatial and temporal resolutions used in the characterization.
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| 30. |
- Hallbjörner, Paul, et al.
(författare)
-
Circularly polarized traveling-wave array antenna with novel microstrip patch element
- 2007
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 6, s. 572-574
-
Tidskriftsartikel (refereegranskat)abstract
- A traveling-wave microstrip array antenna with circular polarization in presented. It uses a novel circularly polarized dual-feed radiating element. The element is a square microstrip patch with a chamfered corner. It is fed by microstrip lines, so radiating element and feed lines can be realized in a single layer. A five-element array is designed and built. Measured performance is presented.
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| 31. |
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| 32. |
- Hallbjörner, Paul, 1966, et al.
(författare)
-
Low-Profile 77-GHz Lens Antenna With Array Feeder
- 2012
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 11, s. 205-207
-
Tidskriftsartikel (refereegranskat)abstract
- A 77-GHz lens antenna for automotive radar applications is presented. It consists of a feeder in the formof a 2 x 2 patch array etched from a single layer on a 100-mu m-thick substrate and a commercially available dielectric lens. Compared to previously published lens antennas, the presented design has the advantages of excellent electrical performance and a low profile in combination with a thin lens. Measurements of port impedance match and radiation patterns are presented. Beam tilt by lateral offset of the lens is demonstrated experimentally.
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| 33. |
- Hallbjörner, Paul, et al.
(författare)
-
Modified planar inverted code antenna for mobile communication handsets
- 2007
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 6, s. 472-475
-
Tidskriftsartikel (refereegranskat)abstract
- The planar inverted cone antenna (PICA) is an antenna type that shows remarkably wideband performance. In its basic configuration, it is mounted on an infinite ground plane, and protrudes lambda/4 above it. This letter presents a study of the possibilities of integrating a PICA in a mobile terminal handset by modifying the ground plane and the radiating element. Port impedance and radiation performance are studied in both simulations and measurement.
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| 34. |
- Hamedani, Mahsa, et al.
(författare)
-
Planar H-Plane Horn Antenna Based on Groove Gap Waveguide Technology
- 2020
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:2, s. 302-306
-
Tidskriftsartikel (refereegranskat)abstract
- H-plane horn antenna using gap waveguide technology is proposed. The advantage of this technology is its air-filled feature, which improves the impedance matching compared with substrate integrated waveguide (SIW) horn antennas. Corrugated walls as soft surfaces are used on the outer surfaces of the upper and lower horn plates, which act as barriers around the aperture of the antenna and reduce its backlobe levels. The bandwidth of the antenna for $| {{S_{11}}} |$< -10 dB is 19-28 GHz and the gain varies between 8.5 and 12 dBi. The total efficiency is better than 88% in the operation bandwidth. This structure has the capability of easily integrating with other planar microwave components. As a demonstration, a coupled-resonator filter is integrated with the antenna to select the desired frequency band and cancel the out-of-band harmonics. For the proof of concept, a prototype model is fabricated and tested, where measurement data agree well with the simulation results.
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| 35. |
- Helander, Jakob, et al.
(författare)
-
Performance Analysis of Millimeter-Wave Phased Array Antennas in Cellular Handsets
- 2016
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 15, s. 504-507
-
Tidskriftsartikel (refereegranskat)abstract
- This letter discusses the usage of high-gain steerable antenna arrays operating at millimeter-wave (mmWave) frequencies for future cellular networks (5G). Based on the probable outline of the 5G networks, a method for characterizing phased array antennas in cellular handsets has been introduced. For analyzing the performance, the total scan pattern of the array configuration together with its respective coverage efficiency are essential to consider in order to compare different antenna designs and topology approaches with each other. Two design approaches and subarray schemes of these have been considered in order to illustrate the relevance of such a characterization method. The results show the importance of evaluating potential array antennas in such manners. The method can be applied to much more complex system models, where polarization diversity, hand and body effect, and statistical modeling of the channel may be included.
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| 36. |
- Hidén Rudander, Jacob, 1986, et al.
(författare)
-
Measurements of RFID Tag Sensitivity in Reverberation Chamber
- 2011
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 10, s. 1345 - 1348
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Tidskriftsartikel (refereegranskat)abstract
- The reverberation chamber is now commonly accepted and used for fast and accurate performance evaluation of mobile phones and other wireless devices for in particular new systems such as LTE 4G and IEEE 802.11n Wi-Fi. In this letter, we describe a new methodology of measuring sensitivity of RFID tags in a reverberation chamber, and we show how the measurements time can be shortened by using the fact that the RFID tag behaves like an ideal threshold receiver. We then extend to tag population measurements that can be used to select the best tag among the many during the same measurement sequence.
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| 37. |
- Hong, Wonbin, et al.
(författare)
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Guest Editorial Antenna-in-Package, Antenna-on-Chip, Antenna-IC Interface: Joint Design and Cointegration
- 2019
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 18:11, s. 2345-2350
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The twenty peer-reviewed letters in this special section examine the design and cointegration of antenna-in-package (AiP), antenna-on-chip (AoC), and antenna ICs (AIC). The letters are categorized in the four distinctive categories: 1) Fabrication technologies (four); 2) Measurement strategies; 3) Applications; and 4) New design and integration strategies. Fruition of major thrusts such as 5G/6G, high-resolution radar and imaging, autonomous driving, and space technology are highly intertwined with the advance of applied electromagnetics. Miniaturization and seamless integration of microwave components and radio systems can enable superior performance, form factor, and cost efficiencies leading to enhanced proliferation of such applications. Historically, radio frequency front ends, antennas, and microwave components have separately evolved using distinct fabrication and measurement technologies.
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| 38. |
- Iupikov, Oleg, 1983, et al.
(författare)
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Domain-Decomposition Approach to Krylov Subspace Iteration
- 2016
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1548-5757 .- 1536-1225. ; 15, s. 1414-1417
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Tidskriftsartikel (refereegranskat)abstract
- Krylov subspace iterative techniques consist of finding the solution of a scattering problem as a linear combination of "generating vectors" obtained through successive matrix-vector multiplications. This letter extends this approach to domain-decomposition. Here, on each subdomain, a subspace is obtained by constructing the segments of each generating vector associated with the subdomain and by weighting these segments independently, which provides more degrees of freedom. The method is tested for scattering by a sphere and a rectangular plate, as well as radiation from connected arrays with strongly coupled antenna elements. It is shown that substantial computational savings can be obtained for the sphere and the array. This opens up new perspectives for faster solutions of multiscaled problems.
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| 39. |
- Jamaly, Nima, 1979, et al.
(författare)
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A Revisit to Spatial Correlation in Terms of Input Network Parameters
- 2012
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 11, s. 1342-1345
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Tidskriftsartikel (refereegranskat)abstract
- An alternative compact formula in terms of input network parameters for calculation of envelope correlations is provided. The main advantage of this formula is that it can be simply modified to include cases of lossy structures and general cases of correlated nonuniform multipath environments. This formula is based on the open-circuit covariance matrix of the multiport antennas. The latter can be either estimated or quickly measured in a reverberation chamber, which removes the need for costly measurements of the embedded far field patterns.
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| 40. |
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| 41. |
- Jamaly, Nima, 1979, et al.
(författare)
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Compact Formulas for Diversity Gain of Two-Port Antennas
- 2010
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 9, s. 970-973
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Accuracy limitation in evaluation of diversity gains based on cumulative distribution function curves is highlighted. New devised closed-form formulas are provided for Selection Combining and Maximum Ratio Combining diversity schemes rendering diversity gain as a function of correlation and radiation efficiencies. Accuracy of these formulas is studied and verified by numerical simulations. These formulas take a central role for the cases when engineers are limited to a finite number of measured voltage samples at different ports to provide them with accurate calculation of ergodic diversity gain. This letter also reveals dependency of different diversity gains upon total embedded efficiencies of branches and underscores the significance of identical efficiencies of two-element terminals for their optimum performance in multipath environments. © 2010 IEEE.
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| 42. |
- Jonsson, B. Lars G., et al.
(författare)
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Array Antenna Limitations
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 12, s. 1539-1542
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Tidskriftsartikel (refereegranskat)abstract
- This letter defines a physical-bound-based array figure of merit for both single and multiband array antennas. It provides a measure to compare their performance with respect to return loss, bandwidth(s), thickness of the array over the ground plane, and scan range. The result is based on a sum-rule result of Rozanov-type for linear polarization. For single-band antennas, it extends an existing limit for a given fixed scan-angle to include the whole scan range of the array, as well as the unit-cell structure in the bound. The letter ends with an investigation of the array figure of merit for some wideband and/or wide-scan antennas with linear polarization. We find arrays with a figure of merit >0.6 that empirically defines high-performance antennas with respect to this measure.
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| 43. |
- Kahkonen, Henri, et al.
(författare)
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Comparison of additively manufactured and machined antenna array performance at Ka band
- 2022
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1536-1225 .- 1548-5757. ; 21:1, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) is a rapidly developing field which potentially decreases the manufacturing costs and enables increasingly complex antenna shapes. Metal-based AM might be particularly useful to manufacture antennas at mm-wave range, because there antennas are physically small enough making additive manufacturing cost efficient, and manufacturing accuracy could still suffice for good electrical performance. In this paper, two additively manufactured and an identical machined fully metallic Ka-band Vivaldi antenna arrays are compared. The manufactured antenna arrays are compared using RF-measurements to conclude the feasibility of AM for manufacturing antenna arrays at mm-wave frequencies. Comparison of the measured radiation patterns and realized gains of each of the antenna arrays between 26 and 40 GHz shows close to identical radiation patterns for all the arrays. A loss in efficiency of 0.51.5 dB is observed in the AM arrays when compared to the machined array due to the used materials and the surface roughness.
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| 44. |
- Karandikar, Yogesh, 1982
(författare)
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Pattern studies of two parallel dipoles above ground plane in eleven configuration as feed for reflector antenna
- 2010
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 9, s. 558-561
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Tidskriftsartikel (refereegranskat)abstract
- The patterns of dual dipoles above a ground plane in the so-called "Eleven" configuration are presented. It is shown that these patterns can be shaped to get different beamwidths to better fit reflectors with different F/D ratios while maintaining beam symmetry. Linear as well as curved dipoles are considered. The effect of finite ground plane is also discussed.
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| 45. |
- Karlsson, Kristian, 1973, et al.
(författare)
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Doppler Spread in Reverberation Chamber Predicted From Measurements During Step-Wise Stationary Stirring
- 2010
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 9, s. 497 - 500
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Tidskriftsartikel (refereegranskat)abstract
- We propose a simple method to accurately predict Doppler spread in a reverberation chamber (RC) by using frequency domain S-parameters measured with a vector network analyzer (VNA) at many fixed stirrer positions (step-wise stationary mode). Thus, the measurements are done under repeatable stationary conditions, so no Doppler shift is present during the actual measurements. Still, this letter shows that the measured S-parameters in step-wise stationary mode can be used to determine Doppler spread appearing during continuous movement of the stirrers. This can be done by computation for any stirrer speed by assuming that the fixed stirrer position steps are the time steps of a continuous movement of the stirrers, and by adding a virtual stirrer speed between the positions corresponding to the desired continuous movement of the stirrers. The computed Doppler spreads are validated over a large frequency band by measuring the time-varying S-parameters for a given stirrer speed.
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| 46. |
- Karlsson, Kristian, et al.
(författare)
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On OTA test in the presence of doppler spreads in a reverberation chamber
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 12, s. 886-889
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, over-the-air (OTA) tests of the performance of the IEEE 802.11p radio system are performed in a reverberation chamber (RC) that is equipped with a fast rotating mode stirrer. By varying the speed of the mode stirrer, different levels of Doppler spreads are created, and the 802.11p radio system is tested accordingly. As expected, the Doppler spread affects the package error rate (PER) of the radio system adversely. In addition to measurements, a simple PER model is presented, which sheds some light into the OTA tests.
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| 47. |
- Kildal, Per-Simon, 1951, et al.
(författare)
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Fundamental Directivity Limitations of Dense Array Antennas: A Numerical Study Using Hannan´s Embedded Element Efficiency
- 2016
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 15, s. 766-769
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Tidskriftsartikel (refereegranskat)abstract
- Hannan introduced in 1964 an embedded element efficiency concept that explains the so-called element-gain paradox in antenna arrays, i.e. that the array gain always is smaller than the sum of the element gains. In the present paper we show for the first time the usefulness of his approach by evaluating directivities and aperture efficiencies of an array of open-ended waveguides by commercial full-wave EM solvers for a large range of element spacing. The results show also that by using embedded element analysis, the realized gain of regular arrays actually becomes equal to the sum of the realized gains of the embedded elements. Thus, the embedded element efficiency ismore practical to use in design and numerical analysis than the more commonly used active element pattern approach. We also show that the embedded element efficiency can be approximatedby a simple formula when the element spacing is smaller than half wavelength.
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| 48. |
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| 49. |
- Kildal, Per-Simon, 1951, et al.
(författare)
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Threshold Receiver Model for Throughput of Wireless Devices with MIMO and Frequency Diversity Measured in Reverberation Chamber
- 2011
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 10, s. 1201-1204
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Tidskriftsartikel (refereegranskat)abstract
- We present a simple theoretical model for the throughput data rate of a wireless LTE device including the improvements of data rate due to diversity in frequency (OFDM) and spatial domains (MIMO) under frequency selective fading. The model is based on defining an ideal threshold receiver for the line-of-sight (LOS) case, corresponding to reception with advanced error-correcting codes. The theoretical throughput model is in agreement with measurements in a reverberation chamber of a commercial LTE device for the 1 x 2 SIMO case, both regarding diversity and MIMO array gains, and it can therefore be used to complement measured results in evaluation of performance of LTE devices.
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| 50. |
- Kolmonen, Veli-Matti, et al.
(författare)
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Measurement-based evaluation of interlink correlation for indoor multi-user MIMO Channels
- 2010
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 9, s. 311-314
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe properties of the single-link multiple-input-multiple- output (MIMO) propagation channels have been analyzed in many studies based on extensive propagation measurements. In this letter, we extend the measurement-based analysis to dual-link MIMO propagation channels. Here, we examine interlink correlation by evaluating the correlation of eigenvectors obtained from multiple MIMO links. We also investigated how the physical propagation phenomena produced the interlink correlation. Results indicate that interlink correlation may exist. Sometimes it is found to be very high also for far separated receive units, depending on similarity of dominant propagation mechanisms between multiple MIMO links and also on antenna array properties.
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