Design of circularly polarized vertical patch antenna for GPS application

Abstract

In this project, in order to satisfy the requirement of the Global Positioning System (GPS), the centre frequency of the antenna included would be 1.262 GHz, 1.616GHz and 2.492 GHz. Moreover, resorting a new design of vertical patch antenna with two extended stubs, the circularly polarization has been realized. Secondly, there are two feeding points into the antenna so that the performance would be better and have higher efficiency than with only one port. Developing progress First of all, simulation would be done before the actual fabrication. Afterward, the testing result will take to compare with the simulation result to evaluate the performance of the tested antenna Performance evaluation Basically, the evaluation of performance would mainly base on the standing wave ratio which is S11 parameter (return loss) and the axial ratio (AR) which is normally used to determine the merit of a circularly polarized antenna. Furthermore, the radiation pattern would be recorded to verify the performance of the antennas in different directions. Application After antennas in three different frequency bands have been designed, a two array structure with two 1.262GHz antennas has been done by simulation. The interference between them in different distance has been tested. Finally, an array with 7 1.262GHz antennas has been constructed. With this array structure, a scanning process can be achieved when the phase of each antenna is varied so the array can still maintain a good performance in different situations. For instance, a ship is vibrating on the sea it can still keep communicating with the GPS system with this array antenna.