Mecanismo para conmutar el sentido de la polarización circular en antenas ranuradas en la banda Ka

This paper presents two slotted array antennas working in the Ka-band with switchable circular polarization capability. The first prototype is a series-fed slotted-waveguide linear array composed of ten T-shaped slots. The second antenna is a two-dimensional array with 2x2 T-shaped slots fed by a corporate distribution network. In both cases, a reflection coefficient below -10 dB has been experimentally observed within the targeted frequency band between 29.5 and 30.5 GHz. Good polarization purity is achieved for both polarization senses and in both prototypes. The fundamental contribution of the paper is to propose a simple mechanism to switch the circular polarization sense in a low-cost, low-profile and high-efficient antenna. The design and experimental results confirm that the solution is suitable for both one- and two-dimensional arrays in the millimeter-wave band

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

Desarrollo de herramienta para la definición de la geometría para el análisis de sistemas de antenas reflectoras

Este Trabajo Fin de Grado tiene como objetivo el diseño de una herramienta de análisis de antenas reflectoras debido a la creciente demanda para el desarrollo de complejos sistemas de antenas que proporcionen las capacidades necesarias hoy en día para las comunicaciones por satélite. El propósito principal es proveer de un medio complementario que permita realizar de forma rápida y sencilla diseños preliminares de sistemas reflectores complejos. Realizando el análisis de diseños teóricos para realizar las pruebas pertinentes antes de llegar a su construcción física. Para llevar a cabo esta herramienta, primero se van a estudiar en detalle las principales técnicas de diseño y las típicas y novedosas geometrías existentes para las antenas de comunicación por satélite, realizando un análisis tanto teórico como del mercado actual. En este sentido también se revisan algunas de las herramientas auxiliares comerciales que se han utilizado en este trabajo. Una vez completada la revisión de las bases teóricas y del estado del arte, se definen las geometrías a ser estudiadas, definiendo los parámetros necesarios para la generación de la geometría y ejecución de las herramientas de análisis auxiliares, como el GRASP. Finalmente, se evalúan los resultados obtenidos para determinar el correcto funcionamiento y la validez de la herramienta. Por último, dado que la extensión de este trabajo ha de ser limitada tanto en tiempo como en espacio, se proponen líneas de trabajo futuro, con variantes y mejoras para esta herramienta en caso de que se desee continuar con su desarrollo

A Modular and Scalable Architecture for Millimeter-Wave Beam-forming Antenna Systems

As the demand for higher data rates increases, wireless technologies (e.g., satellite communications, fifth Generation (5G) wireless communications, and automotive radars) are migrating toward millimeter-wave (mm-W) frequencies (30-300 GHz) to utilize the numerous unused spectra available over this frequency band. For truly ubiquitous coverage over the globe, high throughput Ka-band satellite communication (SATCOM) offers the most optimal and a unique solution for providing world-wide information and sensing. Of particular interest is the development of land, or close-to-land, mobile systems for high data rate communications with continuous coverage for on-the-move commercial platforms, including cars, airplanes, ships, and trains. A modular and scalable phased-array antenna (PAA) architecture wherein the entire phased-array system is made of identical sub-array modules (building blocks) is the most promising approach to develop cost effective and flexible systems for mass market applications. Obviously, such architecture depends on the availability of a high-performance antenna element, antenna subarray modules, and beam-forming circuits. These are the main topics investigated in this PhD thesis. Two approaches were extensively studied in this PhD research to develop intelligent steerable antenna array modules as building blocks for large-scale Ka-band SATCOM applications. The first approach targeted the development of a working prototype for a wide-angle beam-steering Ka-band active PAA (APAA). In this approach, two APAA architectures were proposed, designed, fabricated, and measured to validate the proposed concepts. Both approaches exhibit wide beam-steering angles and fast beam-forming capabilities with full control on amplitude and phase of each antenna element by utilizing an intelligent beam-forming circuit that was developed at CIARS (Centre for Intelligent Antenna and Radio Systems). The first architecture comprises a novel single-fed CP antenna element integrated with the intelligent beam-forming circuit, to construct a wide beam-steering and low-cost CP-APAA. A 4×16 CP-APAA was designed and fabricated using low-cost printed circuit board (PCB) technology and it was tested over the frequency range (29.5-30 GHz) over an angular range of 0o-±40o. The second architecture utilized a highly integrated and wide band dually-polarized antenna element as a core component for the realization of a high-performance, compact, and polarization-agile Ka-band APAA module. The proposed antenna module was used to construct a proof-of-concept 16×16 modular APAA to radiate a high polarization purity pattern over a wide beam-steering angles ≥70o. The second proposed approach investigated two novel wideband and passive steerable antenna concepts as attractive low-cost alternatives suitable for a wide range of emerging mm-W communication systems. Such antenna systems are made of passive components, antennas, phase shifters, and passive feeding networks to reduce the power consumption, cost, and complexity of conventional active electronically steered arrays. In order to build such systems, a high-performance antenna and passive phase shifter (invented at CIARS) were integrated to eliminate the necessity for costly variable gain amplifiers (VGAs). The first proposed concept is a novel CP passive PAA comprised of the proposed single-fed CP antenna integrated with the CIARS phase shifter. The novel high-performance passive phase shifter was controlled by a low-profile and low-power consumption novel magnetic actuator to overcome the limitation of state-of-the-art passive phased arrays. The proposed CP passive PAA was designed, fabricated and tested at Ka-band (29.5-30.5 GHz) over an angular range of 0o-±38o. The second concept proposed here is a novel reconfigurable reflectarray antenna (RAA) element with a true-time-delay functionality. Its reconfigurability is realized by utilizing the proposed phase shifter integrated with an aperture-coupled microstrip patch antenna (ACMPA) to receive and re-radiate the electromagnetic energy efficiently. The proposed RAA element was designed and tested at Ka-band (27.5-30 GHz)

Antennas and Propagation

This Special Issue gathers topics of utmost interest in the field of antennas and propagation, such as: new directions and challenges in antenna design and propagation; innovative antenna technologies for space applications; metamaterial, metasurface and other periodic structures; antennas for 5G; electromagnetic field measurements and remote sensing applications