Wideband Circularly Polarized Antenna With Reconfigurable 2-Dimensional Axial Ratio Beamwidth

Abstract

This paper proposes a wideband circularly polarized antenna with a reconfigurable 2-dimensional axial ratio. For mobile satellite communication, the low profile CP antenna with wide axial ratio scanning and a wide frequency bandwidth is essential. In this paper, we propose the wideband CP antenna with an axial ratio controller. The axial ratio deteriorates when the difference between transverse modes (TM)01 and TM10 gets larger. Therefore, in the proposed antenna, the axial ratio controller is used to compensate for the difference by controlling the amplitude and phase of the received signals. The proposed antenna has three mode states for the 2-dimensional axial ratio region. In a simulation of the wideband CP antenna, the axial ratio was below 3 dB in the 2-dimensional scanning region from -60 degrees to 60 degrees at every azimuth angle in the 20% factional frequency bandwidth. To verify the proposed antenna with the axial ratio controller, the wideband CP antenna is implemented at 5.8 GHz. A low noise amplifier (LNA) and digital phase shifters are employed for the axial ratio controller. The measured axial ratio was below 3 dB in the 2-dimensional scanning region from -60 degrees to 60 degrees at every azimuth angle in the 20% factional frequency bandwidth.