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This work presents a method to determine the required discrete surface distortions to correct errors. The algorithm starts by discretizing the entire reflector surface into triangular patches then by finding a linear relationship between the local distortion and the difference of the distorted and undistorted far fields patterns. A linear system of equations with the distortions as unknowns results...
This paper presents the feasibility study of the beam-waveguide (BWG) system of the third deep-space antenna of ESA (DSA3), which is planned to be built in the Americas. The main challenge of this design consists in combining the X band (7.145-8.5 GHz) and the Ka band downlink channel (31.8-32.3 GHz), already operating in the existing DSA2, with the new receiving band, namely the K band, ranging from...
A novel strategy has been presented to design multi-beam reflector antenna system based on the excitation of a couple of leaky waves by covering the focal plane array with a single thin dielectric layer and tuning the array design to maximize their positive effect. In the worst case scenario of neighboring co-frequency and co-polarized beams an increase of the Geoc of 1 dB over a 6% BW with respect...
Dual-reflector antennas have been investigated for omnidirectional coverage, where the reflector surfaces are bodies of revolution obtained by spinning confocal conic sections or shaped generating curves about a common symmetry axis. The aim of this work is to complement the previous investigations by deriving the GO aperture held of omnidirectional axis-displaced dual-reflector antennas with an arbitrary...
Reflector antenna pattern reconfigurability has been identified as a one of the most interesting and challenging area for satellite telecommunications. Steering and zooming the heard are important capabilities for onboard antenna configurations. This work presents a comparison between two different zooming techniques of a Gregorian confocal dual reflector antenna (GCDRA) when it scans electro-mechanically...
Most antenna applications require maximum gain in a single direction resulting in a pencil beam solution. For some applications antennas are required to provide service with some minimum gain over an angular beam area. Gain-area product (minimum antenna gain within the beam area times the beam area in square degrees) is a useful figure of merit for beams designed to cover an area. Maximizing the minimum...
A new two-layer dielectric rod antenna was developed for near-field probing purpose from 2 to 8 GHz frequency range. The measured and simulated data demonstrate its superiority over other existing probes. Based on its performance, the antenna is not only suitable for scanning the near-field, but for feeding reflectors with small F/D ratios, such as compact ranges.
This paper presents the increasing of the antenna performance, or made it to have high gain. Thus, it can be used for the outdoor transmission. The proposed antenna develops from the U-shaped cross-sectional antenna which typically it is used as an indoor antenna. By installing it with the offset parabolic reflector, many good characteristics antenna are achieved. The offset parabolic reflector is...
A bistatic Gregorian confocal dual reflector antenna for a bomb detection radar system had been presented. The beamwidth is suitable to uniquely illuminate a single human body at 50m away from the antenna. The dual reflector can be used for both transmit and receive simultaneously. The Configuration-1 behaves better than Configuration-2 in terms of directivity whereas it become worst in terms of crosspolar...
The modeling and characterization of an optimized resonant cavity for a passive reconfigurable directive beam antenna near 10 GHz has been presented. It is based on a variable phase metamaterial made of an inductive and a capacitive grid where there is a regular increase of the gap spacing. This variable phase metamaterial allows us to have a forward and backward deflection of up to 30deg. An electronically...
A Ku/Ka dual-band reflectarray has been developed as a demonstration model for the next generation of Titan cloud precipitation radar and altimeter (TCPRA). The reflectarray developed is a substitute of a parabolic cylindrical reflector and it is offset-fed by two linear arrays. The antenna has a 50-cm-square aperture and uses two 2-mil thick membranes for both bands enabling transformation into a...
The purpose of this analysis is to determine the radiation pattern of a monopole antenna placed at the bottom of a Dual Parabolic Reflector with a circular opening on the top. The resultant image of the full dipole should thus appear to float above the opening of the Dual Sphere while the monopole element is actually hidden at the bottom. This configuration may prove useful in conformal antennas and...
In trhis paper, commercial Ku band ground terminal antennas for satellite reception, such as DirecTV's, have played a major role in the digital revolution. Another step further, commercial Ka and Ku band Tx/Rx terminals are evolving around applications requiring data rates from 100Kbps to a few 100Mbps. Examples of these applications include high speed internet, telemedicine, entertainment on- demand,...
A directive ultra-wideband (UWB) antenna exhibiting a gain of more than 7 dBi in the whole FCC UWB frequency band is presented. The excitation of the so called dipole mode on the rod is achieved by a biconical dipole. Placing this configuration in some distance to a reflector results in a flat gain curve. Besides an input reflection of -10 dB from 3 up to 20 GHz, this novel antenna has an excellent...
In this paper we present a simple, practical, and accurate method of estimating the gain reduction of large circular dish reflector antennas caused by central blockage, edge blockage, and plane wave blockage from the struts.
A synthesis approach of electrically small Cassegrain antenna with dielectric supported sub-reflector is presented. In this approach, feed system is designed to realize ideal far field pattern. Full-wave analysis software is used for this simulation. The main-reflector is shaped to compensate feed system phase shift. Calculating the far field pattern of whole Cassegrain antenna by PO, we confirm the...
There are many options to reduce the cross-polarized fields radiated by a patch fed horn. This paper investigates the design of a low cross-polarization grid loaded horn fed by a microstrip patch to be used as the feed for a reflector antenna.
There are many situations where electromagnetic waves are obstructed by some mechanical structure. If the structure is part of or close to an antenna, the obstruction may represent aperture blockage, causing increased sidelobes and reduced gain. The blocking cylinders can be struts supporting the subreflector in a Cassegrain antenna or the feed in a prime-focus paraboloid. The increased sidelobes...
The SCT-based simulation tool consists of a MATLAB code developed to run on a single machine in order to predict the phase-shift for all possible MEMS configurations. The 1024 configurations of a phase-shifter cell are obtained by the UP/DOWN positions of the 10 RF MEMS switches inserted in the slit of the 3 metallic patches (Legay, 2005). This problem represent a very computational demanding task...
In this paper, we propose a modified beam steerable ring antenna array using a transparent AMC reflector, which can be also installed on a windshield. The steerable antenna unit has the feature of radiating only outside of the vehicle and not being influenced by the vehicle body. The remainder of this paper is structured as follows. In section II, a configuration and a concept of the antenna unit...
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