Summary
International Symposium on Antennas and Propagation
2010
Session Number:4FA4
Session:
Number:4FA4-5
Performance Improvement of a Gaussian Backscatter Antenna with Ring Focus Feed
Rangsan Wongsan, Wanwisa Thaiwirot, Monai Krairiksh,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
Low Earth Orbit Satellites (LEO Satellite) are often deployed in satellite constellations, because the coverage area provided by a single LEO satellite only covers a small area that moves as the satellite travels at the high angular velocity needed to maintain its orbit. Since satellite travels at the high velocity, therefore, time required for ground station-satellite communications is limited. Hence, wide beam antennas are needed. At present, the antenna can be used for realizing earth coverage beam in LEO satellite such as shaped reflector antennas. The highly shaped-beam antenna was first developed to give approximately uniform coverage of the earth from satellite antenna [1]. Recently, the similar requirement but different application, a shaped reflector antenna for 60-GHz indoor wireless LAN access point was developed [2]. However, shaping the reflector to obtain shaped beam becomes complicated. This yields a discontinuous surface and more complicated manufacturing process. Thaivirot et al. [3] presented the synthesis of radiation pattern of variety of the shaped backscatters antenna. Each of shape single backscatter antenna is easy to realize and manufacture because the shape of backscatters are elementary geometrical functions. It was found that, the Gaussian backscatter will provide the appropriate characteristics. Therefore, it is suitable for using as an antenna for realizing earth coverage beam in LEO satellite application as shown in Fig.1. To improve gain and efficiency of reflector antenna, the displaced-axis dual reflector antenna was discussed. It was found that the axially displaced ellipse (ADE antenna) provides an excellent choice for compact high-gain spacecraft antenna applications. As a result, this paper presents the axially displaced ellipse antenna. The proposed antenna is a centrally fed displaced axis Gaussian backscatter antenna with a ring focus feed. A backscattering technique is used with the main reflector to achieve wide beamwidth for earth coverage in LEO satellite. Moreover, this approach is fruitful for high-gain antenna applications, especially for Wireless Local Area Network (WLAN) large-scale indoor base station. The proposed antenna will be installed on the centre point of ceiling in the large hall as shown in Fig.2. Physical theory of diffraction (PTD) is utilized for analysis and design. The input parameters of the proposed antenna are derived in closed form. An effective technique for performance improvement of a Gaussian backscatter antenna using ring focus feed is proposed.