| 1. |
- Algaba-Brazalez, Astrid, et al.
(author)
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Flexible 6G antenna systems based on innovative lenses combined with array antennas
- 2023
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In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- In this article, we propose an innovative concept to realize flexible and cost-effective array antenna systems for next generation communication systems. The idea is to tailor the performance of an antenna array to different use case scenarios by applying a customized dielectric lens placed in front of the array. By combining a lens with an array, we can improve certain performance properties of the antenna system and adapt it for unique site locations and requirements. Moreover, the lens may also act as a radome, providing mechanical protection from environmental conditions. This study consists of exploring the possibilities of using a lens to increase the gain of the antenna in certain directions: scanning range close to broadside (from 0 degrees to 30 degrees), and extreme scanning ranges (from 60 degrees to 80 degrees).
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| 2. |
- Castillo Tapia, Pilar, et al.
(author)
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Azimuth and Elevation Scanning with Stacked Modulated Geodesic Luneburg Lenses
- 2022
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In: 2022 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 5-6
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Conference paper (peer-reviewed)abstract
- Here, we propose a modulated geodesic lens antenna array in E-band (56-62 GHz), which has scanning abilities in both azimuth and elevation. The array consists of four lens antenna elements, and each lens antenna produces 13 independent beams that cover 110 degrees in the H-plane with scan losses below 1 dB. The array is fed with a 1:4 power divider comprising three phase shifters to scan in the E-plane. The distance between lenses in the E-plane is 0.7 wavelengths at 60 GHz. The E-plane coverage is 60 degrees with scan losses around -2.2 dB. The maximum realized gain varies from 20.8 to 24.1 dB across the frequency band.
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| 3. |
- Castillo Tapia, Pilar, et al.
(author)
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Characterization of twist-symmetric dielectric waveguides
- 2021
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In: 2021 15th European conference on antennas and propagation (EUCAP). - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- Here, we study the propagation of a twist-symmetric dielectric rod with three different methods: eigenmode solver, multimode Bloch analysis, and scattering parameters of a truncated structure. With the eigenmode analysis, we demonstrate that these structures permit the propagation of circularly polarized modes, and only one of the modes has a stopband in the first Brillouin zone. These results are corroborated with the simulation of a truncated structure, demonstrating that the propagation is only possible for one of the modes at a given frequency band. Finally, the multimode Bloch analysis is used to also characterize the attenuation constant in the stopband.
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| 4. |
- Castillo Tapia, Pilar, et al.
(author)
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Dispersion Analysis of Twist-Symmetric Dielectric Waveguides
- 2021
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In: Photonics. - : MDPI AG. - 2304-6732. ; 8:6, s. 206-206
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Journal article (peer-reviewed)abstract
- We propose a circular twist-symmetric dielectric waveguide that is polarization-selective.In the practical implementation of optical fibers, a selective circular polarization is more convenientthan its linearly polarized counterpart where previous knowledge of the emitted polarization fromthe transmitter is unknown. The analysis of the waveguide was conducted with three methods: aneigenmode approach, simulation of a truncated structure, and the so-called multimodal transfermatrix method (MMTMM). The presented simulations demonstrate that the operational band canbe manipulated by tuning the parameters of the structure. Furthermore, the MMTMM allows for adirect and accurate calculation of the attenuation constant of the rejected circular polarization.
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| 5. |
- Castillo Tapia, Pilar, et al.
(author)
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Mode propagation in glide-symmetric dielectric-filled corrugated waveguides
- 2021
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In: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 1984-1985
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Conference paper (peer-reviewed)abstract
- Glide symmetry in periodic structures introduces several advantages such as low dispersion, wider stopbands, and higher levels of anisotropy. Here, we propose the use of glide symmetry in dielectric-filled corrugated rectangular waveguides. The operation of these filled waveguides is studied by means of a multimodal transfer-matrix approach that carries out a Bloch analysis of the corresponding unit cell to obtain the dispersion diagram of the structure (both the phase shift and the attenuation rate). In this specific configuration, glide symmetry is found to provide a wider backward passband below the cutoff of the non-corrugated housing waveguide.
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| 6. |
- Castillo Tapia, Pilar, et al.
(author)
-
Modulated Geodesic Lens Antenna Array
- 2021
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In: 2021 15Th European Conference On Antennas And Propagation (Eucap). - : IEEE.
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Conference paper (peer-reviewed)abstract
- We present the design of a geodesic Luneburg lens array antenna. The water drop lens is a compact and highly-efficient alternative to the planar Luneburg lens. Our proposed lens antenna is able to steer 110 deg in azimuth with negligible scan losses. On the other hand, the linear array of four elements increases 6 dB of directivity in elevation. A feeding network composed by a 1:4 power splitter and four different phase shifters allows to steer 60 deg in elevation.
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| 7. |
- Castillo Tapia, Pilar, et al.
(author)
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Multimodal Transfer Matrix Approach for the Analysis and Fundamental Understanding of Periodic Structures with Higher Symmetries
- 2022
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In: 2022 16TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- The Multimodal Transfer Matrix Method (MMTMM) is a hybrid approach that efficiently computes the dispersion relation of a periodic structure. It is able to retrieve both the phase shift and attenuation constant of any arbitrary structure susceptible to be analyzed by means of commercial simulators. Here, we propose the use of this method in order to get a physical insight of periodic structures possessing higher symmetries. The MMTMM is here explained and corroborated with two different structures: a glide-symmetric dielectric-filled corrugated rectangular waveguide and a three-fold twist-symmetric bricks embedded in a dielectric waveguide. The first structure allows for the propagation of backward modes below the hollow waveguide cut-off frequency, whereas the second one has handedness selection.
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| 8. |
- Castillo Tapia, Pilar, et al.
(author)
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Radiation efficiency estimation of lossy geodesic lens antennas based on a ray-tracing technique
- 2023
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In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- Here, we propose a generalized ray-tracing (RT) model to accurately compute the radiation patterns and radiation efficiency of lossy non-rotationally symmetric geodesic lens antennas. The RT model uses geometrical optics to obtain the ray paths from the source to the aperture, ray tube theory to calculate the field amplitude distribution, and Kirchhoff's diffraction formula to compute the radiation pattern. Losses in geodesic lenses are mainly produced by the finite conductivity and roughness of the metallic plates. These losses are added to the calculation of the radiation pattern to estimate the radiation efficiency of the antenna. To demonstrate the accuracy of the proposed RT model, a geodesic half-Maxwell fish-eye lens is designed. Radiation patterns, scan losses, and radiation efficiency are calculated. These results agree well with those computed by full-wave simulations.
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| 9. |
- Castillo Tapia, Pilar, et al.
(author)
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Ray-Tracing Model for the Design and Efficiency Calculation of a Monolithic Geodesic Lens Array Antenna
- 2024
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In: 18th European Conference on Antennas and Propagation, EuCAP 2024. - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- We propose the use of a generalized ray-tracing model to design geodesic lens array antennas. This model is capable of computing the radiation patterns and taking into account losses due to finite conductivity and surface roughness, which are essential when producing prototypes as single monolithic pieces. The ray-tracing model is used to design a modified Rinehart-Luneburg lens that shows very good agreement with simulations while significantly decreasing computation time. The profile of the lens is designed in such a way that it can be vertically stacked in an array and produced as a single piece. The lens array antenna is manufactured as a single monolithic piece using the laser powder-bed fusion technique. The tests of this prototype validate the use of additive manufacturing for geodesic lens antennas operating in V-band.
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| 10. |
- Castillo Tapia, Pilar, et al.
(author)
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Study of Forward and Backward Modes in Double-Sided Dielectric-Filled Corrugated Waveguides
- 2021
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In: Sensors. - : MDPI AG. - 1424-8220. ; 21:18
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Journal article (peer-reviewed)abstract
- This work studies the propagation characteristics of a rectangular waveguide with aligned/misaligned double-sided dielectric-filled metallic corrugations. Two modes are found to propagate in the proposed double-sided configuration below the hollow-waveguide cutoff frequency: a quasi-resonant mode and a backward mode. This is in contrast to the single-sided configuration, which only allows for backward propagation. Moreover, the double-sided configuration can be of interest for waveguide miniaturization on account of the broader band of its backward mode. The width of the stopband between the quasi-resonant and backward modes can be controlled by the misalignment of the top and bottom corrugations, being null for the glide-symmetric case. The previous study is complemented with numerical results showing the impact of the height of the corrugations, as well as the filling dielectric permittivity, on the bandwidth and location of the appearing negative-effective-permeability band. The multi-modal transmission-matrix method has also been employed to estimate the rejection level and material losses in the structure and to determine which port modes are associated with the quasi-resonant and backward modes. Finally, it is shown that glide symmetry can advantageously be used to reduce the dispersion and broadens the operating band of the modes.
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