High-resolution algorithms for the reconstruction of the equivalent currents of an antenna by means of modal theory and a priori information

El objetivo del diagnóstico de antenas es la detección de errores en antena fabricadas. Dado que este diagnóstico es difícil de realizar simplemente observando medidas de campo, el diagnóstico se realiza usando las corrientes equivalentes reconstruidas en una superficie próxima a la antena. Esta tesis describe las diferentes posibilidades de realizar esta reconstrucción en una superficie plana a partir de medidas esféricas en campo próximo. En concreto, se estudian extensivamente, y se aplican a situaciones reales, las técnicas de la expansión modal. El problema principal de las técnicas modales es la limitación en la resolución de las corrientes equivalentes. La razón de esta limitación es la pequeña región disponible del espectro de ondas planas (cuya transformada de Fourier son las corrientes equivalentes). En esta tesis se estudia este problema, se muestran varios ejemplos y se describen las posibilidades de mejorar la resolución. De entre estas posibilidades, se propone el uso de una técnica de extrapolación con la que estimar el espectro no visible a partir de la región conocida (el espectro visible) y de información adicional sobre la antena como, por ejemplo, el tamaño de la antena. Entre las diferentes técnicas de extrapolación, se describen y comparan las técnicas más usadas comúnmente. En primer lugar, se aplica el algoritmo iterativo de Papoulis-Gerchberg usando el tamaño y la forma de la antena. Después se describen las versiones directas de este algoritmo, es decir la matriz de extrapolación por filas y columnas y la matriz de extrapolación generalizada. Finalmente, se estudia la transformación PDFT y se compara con los algoritmos anteriores. Todas estas técnicas son aplicadas en situaciones reales con una importante mejora en la resolución. El último capítulo de esta tesis trata de los procedimientos de calibración de sonda. Estos procedimientos son especialmente importantes en el diagnóstico de antenas.Sánchez Escuderos, D. (2009). High-resolution algorithms for the reconstruction of the equivalent currents of an antenna by means of modal theory and a priori information [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8323Palanci

Algoritmos de reconstrucción de corrientes de alta resolución

[ES] La utilización de la técnica holográfica de microondas para la reconstrucción de las corrientes equivalentes a partir de medidas de campo lejano implica una limitación en la resolución de las corrientes obtenidas. La causa de este límite se encuentra en la posibilidad de disponer únicamente de la zona visible del espectro de ondas plano, lo que provoca que la transformada de Fourier del espectro, es decir la corriente deseada, tenga una baja resolución. En este trabajo se propone mejorar la resolución de las corrientes obtenidas. En primer lugar se propone usar el algoritmo de extrapolación de Papoulis-Gerchberg que, a partir de las dimensiones máximas de la antena, obtiene los valores del espectro próximos a la zona visible y, en segundo lugar, se plantea hacer uso de la periodicidad del espectro de las antenas tipo array, para obtener zonas más alejadas. El algoritmo final presentado se aplica a las medidas de una antena en banda X para demostrar la validez del método planteado.[EN] The use of the microwave holographic technique for the equivalent current reconstruction from far field measurements implies a limitation in resolution. The cause of this limit is the availability of only the visible zone of the plane wave spectrum, what causes low resolution in the Fourier transform of this spectrum, i.e. the desired current. The improvement of the obtained currents resolution is proposed in this work. Firstly, the use of the Papoulis-Gerchberg extrapolation algorithm, which, using the dimensions of the antenna, obtains the spectrum values next to the visible zone, is proposed and, secondly, the use of the spectrum periodicity of array antennas is suggested in order to obtain the further zones. Finally, the algorithm is applied to measurements of an X band antenna to prove the validity of the proposed methodSánchez Escuderos, D. (2007). Algoritmos de reconstrucción de corrientes de alta resolución. http://hdl.handle.net/10251/12544Archivo delegad

Antennas and Propagation Lab. Annual Research Report 2019

The Antennas and Propagation Laboratory (APL) focuses its research activities on various areas related to the analysis and design of antennas, as well as to the analysis of different propagation environments. The operating frequency bands under study range from UHF to the V band, thereby covering a wide range of applications, from mobile terminals, to satellite antennas. This report details some of its projects up to 2019

Planar Lens Antenna for High Data Rate Applications

[EN] A low-profile lens antenna formed by 2 metallic rings with strips short-circuiting both rings is presented. The theory of characteristic modes is used to facilitate the design, optimization, and analysis of the structure. Simulations and measurements are presented for the optimized single-layer metallic lens antenna. Measured results show a large operating bandwidth (14.7% relative -14 dB impedance bandwidth) with a maximum directivity above 13.70 dBi and a return loss better than 14 dBThis work has been supported by the Spanish Ministry of Science, Innovation and Universities (Ministerio Ciencia, Innovacion y Universidades) under the projects TEC2016-79700-C2-1-Rand TEC2016-78028-C3-3-P and college scholarship graduate of the National University of ChimborazoSantillan-Haro, D.; Sánchez-Escuderos, D.; Antonino Daviu, E.; Ferrando Bataller, M. (2019). Planar Lens Antenna for High Data Rate Applications. Wireless Communications and Mobile Computing. 1-7. https://doi.org/10.1155/2019/5125287S17Mao, Y., You, C., Zhang, J., Huang, K., & Letaief, K. B. (2017). A Survey on Mobile Edge Computing: The Communication Perspective. IEEE Communications Surveys & Tutorials, 19(4), 2322-2358. doi:10.1109/comst.2017.2745201Jiang, M., Chen, Z. N., Zhang, Y., Hong, W., & Xuan, X. (2017). Metamaterial-Based Thin Planar Lens Antenna for Spatial Beamforming and Multibeam Massive MIMO. IEEE Transactions on Antennas and Propagation, 65(2), 464-472. doi:10.1109/tap.2016.2631589Garbacz, R., & Turpin, R. (1971). A generalized expansion for radiated and scattered fields. IEEE Transactions on Antennas and Propagation, 19(3), 348-358. doi:10.1109/tap.1971.1139935Harrington, R., & Mautz, J. (1971). Theory of characteristic modes for conducting bodies. IEEE Transactions on Antennas and Propagation, 19(5), 622-628. doi:10.1109/tap.1971.1139999Miers, Z., & Lau, B. K. (2015). Wideband Characteristic Mode Tracking Utilizing Far-Field Patterns. IEEE Antennas and Wireless Propagation Letters, 14, 1658-1661. doi:10.1109/lawp.2015.2417351Antonino-Daviu, E., Cabedo-Fabres, M., Sonkki, M., Mohamed Mohamed-Hicho, N., & Ferrando-Bataller, M. (2016). Design Guidelines for the Excitation of Characteristic Modes in Slotted Planar Structures. IEEE Transactions on Antennas and Propagation, 64(12), 5020-5029. doi:10.1109/tap.2016.2618478Capek, M., Hazdra, P., Masek, M., & Losenicky, V. (2017). Analytical Representation of Characteristic Mode Decomposition. IEEE Transactions on Antennas and Propagation, 65(2), 713-720. doi:10.1109/tap.2016.2632725Yang, X., Liu, Y., & Gong, S.-X. (2018). Design of a Wideband Omnidirectional Antenna With Characteristic Mode Analysis. IEEE Antennas and Wireless Propagation Letters, 17(6), 993-997. doi:10.1109/lawp.2018.2828883Santillán-Haro, D., Antonino-Daviu, E., Sánchez-Escuderos, D., & Ferrando-Bataller, M. (2018). Analysis and Design of a Metamaterial Lens Antenna Using the Theory of Characteristic Modes. International Journal of Antennas and Propagation, 2018, 1-8. doi:10.1155/2018/6329531Karimkashi, S., & Kishk, A. A. (2011). Focusing Properties of Fresnel Zone Plate Lens Antennas in the Near-Field Region. IEEE Transactions on Antennas and Propagation, 59(5), 1481-1487. doi:10.1109/tap.2011.212306

Wideband Dual-Polarized Cross-Shaped Vivaldi Antenna

This communication presents a wideband, dual-polarized Vivaldi antenna or tapered slot antenna with over a decade (10.7:1) of bandwidth. The dual-polarized antenna structure is achieved by inserting two orthogonal Vivaldi antennas in a cross-shaped form without a galvanic contact. The measured - 10,\hbox {dB} impedance bandwidth ( {S_{11}} ) is approximately from 0.7 up to 7.30 GHz, corresponding to a 166% relative frequency bandwidth. The isolation ( {S_{21}} ) between the antenna ports is better than 30 dB, and the measured maximum gain is 3.8 11.2 dB at the aforementioned frequency bandwidth. Orthogonal polarizations have the same maximum gain within the 0.7 3.6 GHz band, and a slight variation up from 3.6 GHz. The cross-polarization discrimination (XPD) is better than 19 dB across the measured 0.7 6.0 GHz frequency bandwidth, and better than 25 dB up to 4.5 GHz. The measured results are compared with the numerical ones in terms of S -parameters, maximum gain, and XPD.The authors would like to thank Dr. T. Brown from University of Surrey for proofreading the manuscript, and the anonymous reviewers for the dedicated work to help improve this paper. They would also like to thank T. Jaasko from Pulse Finland for performing the Vivaldi prototype antenna measurements. M. Sonkki would like to thank the Nokia Foundation and Infotech Oulu Doctoral Program for financially supporting his Ph.D. studies. This technology has been licensed by industry.Sonkki, M.; Sánchez Escuderos, D.; Hovinen, V.; Salonen, E.; Ferrando Bataller, M. (2015). Wideband Dual-Polarized Cross-Shaped Vivaldi Antenna. IEEE Transactions on Antennas and Propagation. 63(6):2813-2819. doi:10.1109/TAP.2015.2415521S2813281963

Grating Lobes Reduction Using a Multilayer Frequency Selective Surface on a Dual-Polarized Aperture Array Antenna in Ka-Band

[EN] This paper presents a multilayer frequency selective surface for a dual-polarized aperture array antenna in Ka-band. The elements of the array are cylindrical open cavities with a diameter of at 30 GHz, and spaced one wavelength. Due to this separation between elements, which is limiting and not reducible by the architecture of the feeding network and the size of the radiating element, grating lobes appear. Frequency Selective Surfaces (FSS) can be a solution to this problem without modifying the feeder architecture nor the radiating elements. This paper presents the FSS design for reducing grating lobes level, the antenna assembly, and the experimental validation. The full antenna performance demonstrates that FSS operates in a range identical to the feeder (29.5 GHz to 31 GHz) with the added benefit of reducing the grating lobes level more than 10 dB for both polarizations.This work was supported by the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under Project TEC2016-79700-C2-1-R.Sánchez-Escuderos, D.; Ferrando-Rocher, M.; Herranz Herruzo, JI.; Valero-Nogueira, A. (2020). Grating Lobes Reduction Using a Multilayer Frequency Selective Surface on a Dual-Polarized Aperture Array Antenna in Ka-Band. IEEE Access. 8:104977-104984. https://doi.org/10.1109/ACCESS.2020.3000069S104977104984

Periodic Leaky-Wave Antenna on Planar Goubau Line at Millimeter-Wave Frequencies

A periodic leaky-wave antenna on a planar Goubau line is presented. This transmission line is formed by a planar single-wire waveguide on a thin dielectric substrate. Leakage is produced by adding dipoles along the line on the bottom face of the substrate. A coplanar waveguide is used to feed the antenna, which acts as a smooth transition between the input coaxial cable and the planar Goubau line. The advantage of using this line lies on its losses, lower than those of typical microstrip lines due to the absence of a ground plane. As a result, a higher radiation efficiency than in microstrip-fed antennas can be obtained while keeping similar advantages, e.g., low profile or low production cost. A prototype of the antenna at 40 GHz has been fabricated. Measurements of this prototype are presented in this letter.This work was supported by the Spanish Ministry of Education and Science (Ministerio de Educacion y Ciencia) under Projects TEC2010-20841-C04-01 and CSD2008-00068.Sánchez Escuderos, D.; Ferrando Bataller, M.; Herranz Herruzo, JI.; Cabedo Fabrés, M. (2013). Periodic Leaky-Wave Antenna on Planar Goubau Line at Millimeter-Wave Frequencies. IEEE Antennas and Wireless Propagation Letters. 12:1006-1009. https://doi.org/10.1109/LAWP.2013.2278035S100610091

Dual Circularly-Polarized Slot-Array Antenna in Ka-Band fed by Groove Gap Waveguide

[EN] A dual circularly-polarized slot-array antenna fed by a Groove Gap Waveguide (GGW) and operating in the KaBand is presented in this paper. A simple mechanism is proposed to switch the polarization, from RHCP to LHCP, and viceversa. The lid of the antenna has two pieces: one fixed and one sliding. The fixed piece hosts T-shaped slots, and the sliding block is in charge of adjusting the offset of the perpendicular grooves with respect to the longitudinal slots. Preliminary results show an axial ratio below 1.5 dB for both, RHCP and LHCP, within a bandwidth of 1 GHz centered at 30 GHz.This work has been supported by the Spanish Ministry of Science, Innovation and Universities (Ministerio de Ciencia, Innovacion y Universidades) under project TEC2016-79700-C2-1-R.Ferrando-Rocher, M.; Herranz Herruzo, JI.; Sánchez-Escuderos, D.; Valero-Nogueira, A. (2020). Dual Circularly-Polarized Slot-Array Antenna in Ka-Band fed by Groove Gap Waveguide. IEEE. 421-422. https://doi.org/10.1109/IEEECONF35879.2020.9329473S42142

Low-Profile Radially Corrugated Horn Antenna

[EN] This letter proposes a low-profile horn antenna with radial corrugations. The depth and width of the corrugations are suitably chosen to excite the mode HE11 in the corrugated section. This mode spreads uniformly across the whole aperture, thereby maximizing the radiating area and the aperture efficiency. The good polarization purity of mode HE11 provides a good cross-polar level and a low sidelobe level. The structure is fed by a circular waveguide with two matching elements on the feeding plane that minimize the return loss level. A prototype has been fabricated and measured to operate in the Ku band. The prototype, with a height of just 6.9 mm, i.e., 0.3 lambda0, provides a maximum gain above 12.2 dBi and an aperture efficiency better than 72% within the operating frequency band.This work was supported by the Spanish Ministry of Economics and competitiveness under projects TEC2016-79700-C2-1-R and TEC2016-78028-C3-3-P. (Corresponding author: Daniel Sanchez-Escuderos.)Moy-Li, HC.; Sánchez-Escuderos, D.; Antonino Daviu, E.; Ferrando Bataller, M. (2017). Low-Profile Radially Corrugated Horn Antenna. IEEE Antennas and Wireless Propagation Letters. 16:3180-3183. https://doi.org/10.1109/LAWP.2017.2767182S318031831

Dual-polarized planar lens antenna designed with a quad-ridged frequency selective surface

This is the peer reviewed version of the following article: Moy¿Li, HC, Sánchez¿Escuderos, D, Antonino¿Daviu, E, Ferrando¿Bataller, M. Dual¿polarized planar lens antenna designed with a quad¿ridged frequency selective surface. Microw Opt Technol Lett. 2019; 61: 479¿ 484, which has been published in final form at https://doi.org/10.1002/mop.31583. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] This letter presents a microwave planar lens illuminated by a radially corrugated horn antenna. The lens is formed by a set of 5x5 multilevel unit cells working as a frequency selective surface. Each layer of the unit cells is formed by a square metallic ring with two sets of orthogonal stubs. The length of each set of stubs controls the transmission phase shift for each polarization, so that the lens can be configured independently for two orthogonal polarizations. The lens presented in this letter makes use of this operation to compensate the phase profile of the radiation pattern generated by the feeder. A prototype, with the lens located at 0.59 lambda from the feeder, has been fabricated. Measured results show a maximum gain above 14.44 dBi within the operating frequency band (12.55-13.10 GHz), and a crosspolar level below -32 dB within the HPBW.Spanish Ministry of Economics and Competitiveness, Grant/Award Number: TEC2016-78028-C3-3-P and TEC2016-79700-C2-1-R.Moy-Li, HC.; Sánchez-Escuderos, D.; Antonino Daviu, E.; Ferrando Bataller, M. (2019). Dual-polarized planar lens antenna designed with a quad-ridged frequency selective surface. Microwave and Optical Technology Letters. 61(2):479-484. https://doi.org/10.1002/mop.31583S479484612Zhou, H., Qu, S., Lin, B., Wang, J., Ma, H., Xu, Z., … Bai, P. (2012). Filter-Antenna Consisting of Conical FSS Radome and Monopole Antenna. IEEE Transactions on Antennas and Propagation, 60(6), 3040-3045. doi:10.1109/tap.2012.2194648Costa, F., Monorchio, A., & Manara, G. (2010). Analysis and Design of Ultra Thin Electromagnetic Absorbers Comprising Resistively Loaded High Impedance Surfaces. IEEE Transactions on Antennas and Propagation, 58(5), 1551-1558. doi:10.1109/tap.2010.2044329Bossard, J. A., Liang, X., Li, L., Yun, S., Werner, D. H., Weiner, B., … Khoo, I. C. (2008). Tunable Frequency Selective Surfaces and Negative-Zero-Positive Index Metamaterials Based on Liquid Crystals. IEEE Transactions on Antennas and Propagation, 56(5), 1308-1320. doi:10.1109/tap.2008.922174AgahiS MittraR. Design of a cascaded frequency selective surface as a dichroic subreflector. IEEE Antennas and Propagation Society International Symposium; 1990:88‐91.Glatre, K., Renaud, P. R., Guillet, R., & Gaudette, Y. (2015). The Eutelsat 3B Top-Floor Steerable Antennas. IEEE Transactions on Antennas and Propagation, 63(4), 1301-1305. doi:10.1109/tap.2014.2382657FonsecaNJ MangenotC. Low‐profile polarizing surface with dual‐band operation in orthogonal polarizations for broadband satellite applications. In: IEEE European Conference on Antennas and Propagation; 2014:471‐475.CailleG ChiniardR ThevenotM et al. Electro‐magnetic band‐gap feed overlapping apertures for multi‐beam antennas on communication satellites. In: IEEE European Conference on Antennas and Propagation; 2014:963‐967.Abdelrahman, A. H., Elsherbeni, A. Z., & Fan Yang. (2014). Transmitarray Antenna Design Using Cross-Slot Elements With No Dielectric Substrate. IEEE Antennas and Wireless Propagation Letters, 13, 177-180. doi:10.1109/lawp.2014.2298851Abdelrahman, A. H., Elsherbeni, A. Z., & Fan Yang. (2014). High-Gain and Broadband Transmitarray Antenna Using Triple-Layer Spiral Dipole Elements. IEEE Antennas and Wireless Propagation Letters, 13, 1288-1291. doi:10.1109/lawp.2014.2334663Nematollahi, H., Laurin, J.-J., Page, J. E., & Encinar, J. A. (2015). Design of Broadband Transmitarray Unit Cells With Comparative Study of Different Numbers of Layers. IEEE Transactions on Antennas and Propagation, 63(4), 1473-1481. doi:10.1109/tap.2015.2402285Moy-Li, H. C., Sanchez-Escuderos, D., Antonino-Daviu, E., & Ferrando-Bataller, M. (2017). Low-Profile Radially Corrugated Horn Antenna. IEEE Antennas and Wireless Propagation Letters, 16, 3180-3183. doi:10.1109/lawp.2017.2767182Moy‐LiHC Sánchez‐EscuderosD Antonino‐DaviuE Ferrando‐BatallerM. Design of planar metallic microwave lenses for multiple spot‐beam systems. In: IEEE European Conference on Antennas and Propagation; 2017:2341‐2345.Sanchez-Escuderos, D., Moy-Li, H. C., Antonino-Daviu, E., Cabedo-Fabres, M., & Ferrando-Bataller, M. (2017). Microwave Planar Lens Antenna Designed With a Three-Layer Frequency-Selective Surface. IEEE Antennas and Wireless Propagation Letters, 16, 904-907. doi:10.1109/lawp.2016.261434