Design of broadband circularly polarized patch antenna with wide beamwidth

Abstract

This project studies mainly the design techniques of wideband circularly polarized patch antenna with broadened beamwidth. Through combining different features, an axial ratio bandwidth (<3dB) of 3.2% can be achieved within the impedance bandwidth with a broad beamwidth of around 120 degrees. The dominant radiating mode consists of Left Hand Circularly Polarized (LHCP) fields. The main objectives of designing a patch antenna include broadening the impedance bandwidth - which is an inherent disadvantage of patch antenna - and moreover, the axial ratio bandwidth if the antenna is to work circularly polarized. To achieve this, an imbalanced U-slot is adopted together with truncated corners on the radiating plate. Another goal is to broaden the beamwidth, realized by forming metallic walls around the main patch. Following the introduction, systematic comparisons are made in this report regarding each important parameter of the antenna by varying a designated dimension while keep others unchanged. Then, the resultant antenna will be presented and lastly, some techniques for further improvement will be suggested. All the simulations in this report are done using Zeland IE3D.