Microstrip patch antenna for SDARS reception

The paper is concerned with the design of the receiving antenna for SDARS (satellite digital audio service). SDARS is mostly directed at vehicles, so that the antenna has to be designed as a planar structure in order to be installed on the roof. The microstrip antenna is suited to these design conditions. The microstrip antenna has the demerits of narrow bandwidth and low gain and power handling, but has the merits of small size and light weight, also, it can be largely produced by photo etching technologies. In addition, it is easily installed in a planar structure and is not restricted by the space of installation. SDARS uses two or three satellites to cover the entire service area of America and shows the properties of wide beamwidth and good axial ratio as the electrical characteristics because circular polarization is used. Therefore, the paper mainly focuses on the design of an antenna which has a wide beamwidth and good axial ratio characteristics. The resulting antenna has the wide impedance bandwidth of 17.8% (415 MHz) and the axial ratio is below 3 dB over the bandwidth, including the frequency bandwidth for SDARS reception. The size of antenna is minimized by the structure of the junction of two dielectric substrates, with the patch built on top and a power divider built on the bottom.