A High-Isolation, Wideband and Dual-Linear Polarization Patch Antenna

The design of a dual-polarization stacked patch antenna to be used in GSM-UMTS base station arrays is presented. The patch shows a high matching level in a broadband and isolation between elements that make it a suitable radiating element for base station arrays. Moreover, the most relevant achievement of this element is the isolation between the two polarization ports of the same element in the antenna operating bandwidth. A prototype has been manufactured and measured. The measurements, that match the design objectives, are also presented

C-Ku-Band Dual-Polarized Array Element for Shared-Aperture Frequency-Scanning Array

Accurate now-casting and forecasting could prevent losses and reduce risks caused by severe weather. Key observation to improve our knowledge of the weather is the ocean vector wind. National Oceanic and Atmospheric Administration (NOAA) is embarking on an ambiguous but needed effort to launch a new satellite-based instrument called the Dual Frequency Scatterometer (DFS) that will provide accurate global mapping of the ocean vector wind in a timely manner. The Advanced Wind and Rain Airborne Profiler (AWRAP) can play a pivotal role for this mission by providing critical measurements to improve the geophysical model function that DFS will relay on to estimate the winds. AWRAP requires a novel antenna to collect dual-polarized, dual-wavelength measurements. This work develops a subarray for the AWRAP antenna that will enable it acquire the necessary measurements from the NOAA WP-3D aircraft. By sharing the aperture for both C (5.3 GHz) and Ku (13.8 GHz) bands, this antenna array utilizes the given circular area as efficiently as possible. In both bands, the array is capable of forming and scanning a narrow beam in the x-z plane in the range 40°-60° o normal within 10% of frequency bandwidth, for both vertical and horizontal polarizations. Each subarray consists of nine dual-polarized Ku-band microstrip patch antennas and two perpendicular C-band slot antennas, sharing the aperture. Microstrip patches and their stripline feed networks are integrated into an 8-layer printed circuit board (PCB) and the slots are formed on an aluminum plate under the PCB. The PCB covers the slots, but they can radiate through the openings in the ground planes of the PCB. The C-band slots are positioned between Ku-band patches every third patch spacing. In total, four separate feed networks are required to drive the antenna elements in two bands for two polarizations. In order to achieve lower loss and higher antenna efficiencies in a small space, several transmission line technologies (namely, rectangular waveguides, suspended striplines and striplines) are used to deliver the power to the antenna elements. In order to pass the signal between different media, a broad-band perpendicular E-plane waveguide-to-suspended stripline transition is designed and fabricated in Ku band. A frequency bandwidth of 12% and an insertion loss as low as 0.09 dB are achieved in measurement. Measured input return loss of the Ku-subarray is more than 9 dB in the entire frequency bandwidth and realized gains are better than 10 dBi. Cross-polarization levels are less than -20 dB in the lower frequencies. However, in the higher frequencies, cross-polarization levels increase to -15 dB. It is proposed to use mirrored feed technique to improve cross-polarization levels of the array. For the C-subarray, measured input return loss is better than 12 dB in the entire frequency bandwidth. Measured realized gain at the center frequency is -12 dBi, and cross-polarization level is better than -20 dB

Dual-Band Integrated Antennas for DVB-T Receivers

An overview on compact Planar Inverted-F Antennas (PIFAs) that are suitable for monitor-equipped devices is presented. In particular, high efficiency PIFAs (without any dielectric layer) with a percentage bandwidth (%BW) greater than 59% (470–862 MHz DVB-T band) are considered. In this context, two PIFA configurations are reviewed, where a dual-band feature has been obtained, in the 3300–3800 MHz (14% percentage bandwidth) WiMAX and 2400–2484 MHz (2.7% percentage bandwidth) WLAN IEEE 802.11b,g frequency bands, respectively, to also guarantee web access to on-demand services. The two PIFAs fill an overall volume of  mm3 and  mm3, respectively. They are composed of a series of branches, properly dimensioned and separated to generate the required resonances. Finally, to show the extreme flexibility of the previous two configurations, a novel dual-band L-shape PIFA has been designed. A reflection coefficient less than −6 dB and −10 dB and an antenna gain of around 2 dBi and 6.3 dBi have been obtained in the 470–862 MHz DVB-T band and the 2400–2484 MHz WLAN band, respectively. The L-shape PIFA prototype can be obtained by properly cutting and folding a single metal sheet, thus resulting in a relatively low-cost and mechanically robust antenna configuration

Enhancement of Millimeter-Band Transceivers with Gap Waveguide Technology

Mención Internacional en el título de doctorIt is known to all that year after year in modern society there is an urgent demand to consume wirelessly, and even stream ever larger multimedia content. High-frequency technologies have made it possible to go from transmitting analog voice and SMS text messages, to now transmitting live video in 4K quality from a mid-range smartphone. The way to measure these advances is by the bandwidth (Mb/s) reserved for each network user and the cost required to achieve it. To achieve even higher bandwidths, it is essential to improve signal coding techniques or increase the frequency of the signal, for example: to the mmWave bands (25GHz - 100 GHz), where these high-frequency techniques come into play. However, there is a frequency limit where current planar technology materials - such as the printed circuit boards used to build RF devices - are so lossy that they are not suitable at these mmWave frequencies. Current commercial solutions consist of guiding the electromagnetic energy with hollow metallic waveguides, but they suffer from the problem that as the frequency increases the diameter of these waveguides gets smaller and smaller, so manufacturing tolerances increase exorbitantly. Not to mention that they are usually manufactured in two parts, one upper and one lower, whose joints are not always perfect and produce energy losses. With these issues in mind, in 2009 the theory and basic science of a new electromagnetic energy guidance technology called Gap Waveguide was proposed, which is based on the use of metasurfaces constructed with periodic elements similar to a bed of nails. There are several implementations of this technology, but the three main ones are: Ridge, Groove and Inverted Microstrip Gap Waveguide. The latter is the most compatible with conventional planar manufacturing technologies and therefore the most cost-effective, although it also has drawbacks mainly in terms of losses when compared to the other versions. This thesis aims to deepen the study of the Inverted Microstrip guidance technology, its limitations and to develop with it some of the needed components in RF systems such as filters, diplexers, amplifiers, antennas, etc. Regarding the methodology for this thesis, a commercial simulation software for the analysis of antennas and components, CST Microwave Studio [1], has been used. AWR Microwave Office [2], a circuit simulator, has also been used to complement the simulations. On the other hand, there is a laboratory for the manufacture of prototypes in printed technology (with some limitations in terms of resolution) and the corresponding measurement laboratory, which includes network analyzers up to 40 GHz, spectrum analyzers and an anechoic chamber.This thesis arose under the Spanish Ministry of Science and Innovation (MINECO) and European Regional Development Fund (ERDF) project, called "Antenna for Mobile Satellite Communications (SATCOM) in Ka-Band by means of metasurfaces (2016-2019)", with reference TEC2016-79700-C2-2-R. Under this contract, the author signed an FPI research contract.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Íñigo Cuiñas Gómez.- Secretario: Ángela María Coves Soler.- Vocal: Astrid Algaba Brazále