A Single-Feed Array Antenna With Sum- and Difference-Patterns Using Planar Magic-Ts

This paper presents a single-feed microstrip array antenna for dual beam switching functionality. The proposed antenna consists of four linearly polarized microstrip antennas, two planar magic-Ts, and one single-pole double-throw (SPDT) switch. The magic-Ts distribute in- or anti-phase signals to the antenna arrays to generate sum or difference radiation patterns on the y-z plane. The switching between the radiation patterns is achieved by using the SPDT switch. The concept is experimentally verified using a 5.8-GHz prototype. The measured 10-dB impedance bandwidth is around 2.8% with better than 10.9-dBi gain at 5.75 GHz. The cross-polarization suppression is better than 20 dB for both radiation patterns.