| 1. |
- Castillo Tapia, Pilar, et al.
(författare)
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V-Band Monolithic Additive-Manufactured Geodesic Lens Array Antenna
- 2023
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 22:10, s. 2527-2531
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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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| 2. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Experimental Validation of a Bespoke Lens for a Slot Log-Spiral Feed
- 2020
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 19:4, s. 557-560
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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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| 3. |
- Gupta, Nitish Kumar, et al.
(författare)
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Singular Phase Characteristics of Electromagnetic Absorbers and a Framework for Low-RCS Target Detection
- 2023
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 22:1, s. 134-138
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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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| 4. |
- Hamedani, Mahsa, et al.
(författare)
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Planar H-Plane Horn Antenna Based on Groove Gap Waveguide Technology
- 2020
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:2, s. 302-306
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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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| 5. |
- 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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| 6. |
- Kruglov, Dmitrii, 1994, et al.
(författare)
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Contactless Measurement of a D-Band On-Chip Antenna Using an Integrated Reflective Load Switch
- 2024
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 23:3, s. 1075-1079
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Tidskriftsartikel (refereegranskat)abstract
- A novel measurement setup is proposed for the contactless characterization of on-chip antennas. A D-band patch antenna is fabricated on a 100 μm-thick GaAs substrate and is monolithically integrated with a reflective load switch to allow for fast electronic control of the antenna port termination. The antenna under test is illuminated by a reference antenna in the anechoic chamber after which the impedance and gain of the patch antenna are reconstructed from the change in backscattered field due to different port terminations. In our experiment, the over-the-air reconstructed antenna input impedance exhibits a frequency shift of less than 1% with respect to the (non-ideal) on-wafer probe measurement in the 115–130 GHz frequency range. Furthermore, the measured realized gain of 0.9±0.5 dBi is close to the simulated one of 1.1 dBi.
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| 7. |
- Liao, Qingbi, et al.
(författare)
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Switchable Bidirectional/Unidirectional LWA Array Based on Half-Mode Substrate Integrated Waveguide
- 2020
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 19:7, s. 1261-1265
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Tidskriftsartikel (refereegranskat)abstract
- A novel leaky-wave antenna array with switchable radiation patterns is designed and manufactured at X-band based on a half-mode substrate integrated waveguide. It generates endfire and broadside radiation patterns in two orthogonal planes. The endfire radiation is bidirectional in the xz plane, and the broadside radiation is unidirectional in the yz plane. These two radiations can be controlled by triggering in-phase or out-of-phase port excitations. The excitations also enable the scanning beams to switch between xz and yz planes. A feeding network is designed with a 3 dB coupler and a phase tuner to generate the in-phase and out-of-phase excitations. In the feeding network, the phase difference is realized without using any phase shifter. The feeding network has two input ports, one for the in-phase excitation and one for the out-of-phase excitation. A prototype antenna was manufactured and tested to validate the concept.
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| 8. |
- Lundgren, Johan, et al.
(författare)
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Fully Metallic Dual-Band Linear-to-Circular Polarizer for K/K-a-band
- 2021
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 20:11, s. 2191-2195
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Tidskriftsartikel (refereegranskat)abstract
- A dual-band polarizer is presented that converts linear polarization into circular polarization with orthogonal handedness in the satcom bands 19.7-20.2 GHz and 29.5-30 GHz. The polarizer consists of three identical cascaded perforated metallic screens, whose perforations are periodically repeated crosses of two sizes. Unlike previously reported dual-band polarizers, our design is fully metallic, which results in low losses and makes it suitable for space applications. A prototype of the polarizer with 20 x 20 unit cells is manufactured, and the measurement results agree well with the simulated results. In the nominal satcom bands, the measured axial ratio and the insertion loss are better than 1.7 and 0.67 dB. In the bands 18.9-20.3 GHz and 29.1-30.1 GHz, the measured axial ratio and insertion loss are below 3 and 1 dB.
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| 9. |
- Mystilidis, Christos, et al.
(författare)
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On the Application of Numerical Methods to Hallen's Equation : The Case of a Lossy Medium
- 2020
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 19:2, s. 272-276
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Tidskriftsartikel (refereegranskat)abstract
- A previous paper (Fikioris and Wu, 2001) analyzed in detail the difficulties associated with the application of numerical methods to Hallen's integral equation with the approximate kernel for the case of a lossless surrounding medium. This letter extends to the case where the medium is conducting and points out similarities and differences between the two cases. Our main tool is an analytical/asymptotic study of the antenna of infinite length.
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| 10. |
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