Resolución de problemas electromagnéticos complejos mediante análisis circuital generalizado

El objetivo de esta tesis se centra en extender el tratamiento circuital característico de los problemas cerrados al análisis de problemas abiertos. Las ventajas que se derivan de tal extensión son las mismas que encontramos en un problema cerrado: la sistematicidad en el tratamiento de los problemas, la facilidad para combinar distintas técnicas y el poder disponer de una caracterización unitaria de cada estructura e independiente de la excitación aplicada. Para ello se emplea la matriz de admitancias generalizadas como vehículo de conexión entre problemas que han sido analizados con diversas técnicasValero Nogueira, A. (1997). Resolución de problemas electromagnéticos complejos mediante análisis circuital generalizado [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/5949Palanci

A Report on New Antennas for Satellite Communications on-the-move in Ka-band

This project was initiated in 2017 within the framework of the Spanish national research program, funded by the ministry of economics, industry and competitiveness. The scope of this project is focused on the design of ground terminals for the new generation of high-throughput satellites operating in the Ka band (from 19 to 31 GHz

Comments on “Ka-Band Coplanar Magic-T Based on Gap Waveguide Technology”

In the title paper, the author proposes a Ka-Band Coplanar Magic-T Based on Gap-Waveguide (GW) Technology. The major novelty claimed in the paper is the combination of ridge-gap and E-plane groove-gap waveguides for Ka-band applications. However, such combination of these two types of waveguides in GW technology was firstly proposed in 2017. This combination allows for the realization of numerous devices, and distribution networks in the millimeter-wave band. This comment aims to properly frame the evolution of the use of RGW-GGW networks and how their use can be useful for new mm-wave band devices. While the author’s Magic-T introduces a new feature by using a 4-port network, it is clear that the concept relies on previous ideas not mentioned in the manuscript and this can lead to confusion about its actual novel contributions. In addition, we intend to give the microwave community a proper perspective of the above work’s frame of reference

Test-Fixture for Suspended-Strip Gap-Waveguide Technology on Ka-Band

This letter presents a Test-Fixture for a Suspended-Strip Gap-Waveguide technology that provides a fast measurement system for the prototyping stage. For this purpose, a transition from standard rectangular waveguide to this new technology has been developed. A TRL kit and a repeatability study have been made to ensure the reliability of the process, and several straightforward circuits have been manufactured and measuredThis work was supported by the Spanish Ministerio de Ciencia e Innovacionunder projects TEC2010-20841-C04-01 and CSD2008-00068.Gahete Arias, C.; Baquero Escudero, M.; Valero-Nogueira, A.; Vila Jiménez, A. (2013). Test-Fixture for Suspended-Strip Gap-Waveguide Technology on Ka-Band. IEEE Microwave and Wireless Components Letters. 23(6):321-323. https://doi.org/10.1109/LMWC.2013.2258000S32132323

60-GHz Single-Layer Slot-Array Antenna fed by Groove Gap Waveguide

[EN] A V-band single-layer low-loss slot-array antenna is presented in this letter. Radiating slots are backed by coaxial cavities, which are fed through a groove gap waveguide E-plane corporate feed network. Cavity resonances are created by shortening nails with respect to the surrounding ones. This fact enables a compact single-layer architecture since coaxial cavities and feeding network can share the same bed of nails. A 16 x 16 array is designed, constructed, and measured to demonstrate the viability of this concept for high-gain single-layer slot-array antennas. In addition, this solution can be extended to circular polarization by seamlessly adding a polarizer above the slots without changing the feeding network piece. Measurements show a relative bandwidth of 10% with input reflection coefficient better than -10 dB and a mean antenna efficiency above 70% within the operating frequency band (57-66 GHz).This work was supported by the Spanish Ministry of Economy and Competitiveness under Project TEC2016-79700-C2-1-R.Ferrando-Rocher, M.; Valero-Nogueira, A.; Herranz Herruzo, JI.; Teniente, J. (2019). 60-GHz Single-Layer Slot-Array Antenna fed by Groove Gap Waveguide. IEEE Antennas and Wireless Propagation Letters. 18(5):846-850. https://doi.org/10.1109/LAWP.2019.2903475S84685018

A Comparison between Natural Resonances and Characteristic Mode Resonances of an infinite circular cylinder

[EN] Here, some aspects in the interpretation of the solutions of a PEC infinite circular cylinder with the Theory of Characteristic Modes are presented. First, natural resonances and characteristic mode resonances (CMRs) are introduced and compared. Second, characteristic eigenvalues are used to find those natural resonances considering complex ka values. Furthermore, by linking the standard and the generalized eigenvalue problems, a relation between natural resonances and characteristic mode eigenvalues is shown. Finally, the thesis stating that external CMR does not imply maximum field scattering is also demonstrated.Bernabeu Jiménez, T.; Valero-Nogueira, A.; Vico Bondía, F.; Kishk, AA. (2017). A Comparison between Natural Resonances and Characteristic Mode Resonances of an infinite circular cylinder. IEEE Transactions on Antennas and Propagation. 65(5):2759-2763. doi:10.1109/TAP.2017.2670368S2759276365

Full-Metal K-Ka Dual-Band Shared-Aperture Array Antenna Fed by Combined Ridge-Groove Gap Waveguide

© 2019 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] This letter presents an 8 x 8 dual-band shared-aperture array antenna operating in K-(19.5-21.5 GHz) and Ka-band (29-31 GHz) using gap waveguide technology. Radiating elements consist of circular apertures located on the top plate of the antenna and excited by two stacked cavities with different diameters for dual-frequency operation. A waffle grid is used on top to increase the effective area of apertures and reduce grating lobes. Each stacked cavity is fed by its appropriate corporate-feeding net-work: The upper feeding layer operates at 20 GHz band, and the lower one at 30 GHz band. As a result, the antenna presents two ports, one for each band, which radiate a directive far-field pattern with linear polarization, orthogonal to each other. Experimental results show impedance and radiation pattern bandwidths larger than 1.5 GHz in both bands.This work was supported by the Spanish Ministry of Economics and Competitiveness under Project TEC2016-79700-C2-1-R.Ferrando-Rocher, M.; Herranz Herruzo, JI.; Valero-Nogueira, A.; Bernardo Clemente, B. (2019). Full-Metal K-Ka Dual-Band Shared-Aperture Array Antenna Fed by Combined Ridge-Groove Gap Waveguide. IEEE Antennas and Wireless Propagation Letters. 18(7):1463-1467. https://doi.org/10.1109/LAWP.2019.2919928S1463146718

Performance Assessment of Gap Waveguide Array Antennas: CNC Milling vs. 3D Printing

(c) 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] This letter focuses on comparing manufacturing features of three-dimensional (3-D) printing techniques versus conventional computer numerical control (CNC) milling in the context of gap waveguide technology. To this end, a single-layer array antenna has been designed as a demonstrator. The antenna under test, intended for Ka-band, is composed of 8 x 8 radiators fed by a gap-waveguide (GW) corporate network. Two identical prototypes have been manufactured, but each applying a different fabrication technique, i.e., 3-D printing and CNC milling. The experimental results of both antennas are presented, under the same conditions and measurement facilities. The conclusions drawn in this letter provide a valuable assessment of 3-D-printing viability for GW arrays against the conventional milling technique.This work was supported by the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under Grant TEC2016-79700-C2-1-R.Ferrando-Rocher, M.; Herranz Herruzo, JI.; Valero-Nogueira, A.; Bernardo Clemente, B. (2018). Performance Assessment of Gap Waveguide Array Antennas: CNC Milling vs. 3D Printing. IEEE Antennas and Wireless Propagation Letters. 17(11):2056-2060. https://doi.org/10.1109/LAWP.2018.2833740S20562060171

True-Time-Delay Mechanical Phase Shifter in Gap Waveguide Technology for Slotted Waveguide Arrays in Ka-band

This paper proposes a novel all-metal mechanical phase shifter in gap waveguide technology. The phase shifter is aimed at providing beam-scanning capabilities to conventional slot array antennas along the elevation plane. To validate experimentally the beam-steering functionality, a 4×8 slot-array antenna has been designed and fabricated, along with the phase-shifting mechanism. The whole antenna consists of two pieces: a lower rotatable block, which changes the length of concentric Groove Gap Waveguides, and an upper fixed block, where the slot-array antenna is placed. Experimental results validate the proposed concept, having obtained steering angles of up to 25∘, with gain levels around 20 dBi with an antenna efficiency close to 90%. A reflection coefficient below –10 dB is achieved for a wide range of rotation angles from 29.5 GHz to 30.5 GHz. The proposed phase shifter is completely scalable to any array size and its true-time-delay nature enables wide steering ranges for closely-spaced slot arrays with wideband radiation performance.This work was supported by the Spanish Ministry of Economics and competitiveness under project TEC2016-79700-C2-1-R

Novel Asymmetric T-Shaped Radiating Element for Circularly-Polarized Waveguide Slot Arrays

Waveguide slot arrays are a widely used solution to attain linearly-polarized high-gain antennas. In this paper, an all-metal T-shaped radiating element is conceived with the aim to replace the usual rectangular slots and attain circularly-polarized arrays, preserving their good properties. The polarization conversion is made possible thanks to the inclusion of a parasitic arm perpendicular to the main active slot. Due to the fact that this second arm is not directly fed by the waveguide but coupled to the active slot, the T-shaped element can be used in any array originally formed by metallic rectangular slots. The design of resonant shunt arrays has been addressed here for validation purposes. The experimental results of two sample linear arrays at 30 GHz demonstrate the design accuracy and manufacturing reliability, reporting an axial ratio below 2 dB within a bandwidth of 1.9 GHz and a peak efficiency around 98%.This work was supported by the Spanish Government, Agencia Estatal de Investigación (AEI), under project PID2019-107688RB-C22