S-Band Dual Circularly Polarized Multi-Beam Shared Aperture Phase Array Antenna for Ground Reception System

A dual circularly polarized S-band multi-beam shared aperture phase array antenna for ground based communication and data acquisition system has been discussed in this manuscript. The objective is to simultaneously produce multiple beams--using the same antenna aperture. Each beam is independently assigned to separate airborne flying objects for tracking and health data analysis purpose. The antenna system is capable of producing simultaneous dual circular polarization, namely left hand and right hand circular polarization. Each beam is independently steered electronically over ±45° without much degradation of the gain and beamwidth at scan edge. Side lobe level is reduced below 30 dB using Taylor distributed amplitude tapering. The overall array antenna produces a 3dB beamwidth of about 14°with boresight gain of is 20dBi over the entire operating band. However, the gain decreases by ~ 3dB at scan edge of $\pm 45^{\circ}$ The system has been realized and experimentally validated. The realized impedance bandwidth is wider than 10% at each of the ports with inter-port isolation $\geq 18$ dB. Measured axial ratio is better than 3 dB over the entire operating band.