Design and Implementation of Beam Steering Using 8×8 Butler Matrix on X-Band Array Antenna for AESA Radar

The beam steering system which consists of rectangular array antenna and $8 \times 8$ Butler Matrix are presented. This system can work properly at 9.4 GHz for AESA radar of the fighter aircraft usage. The antenna has eight linear arrays with 40 single patches and was successfully implemented since the average value of return loss in each linear array is 32.18 dB. The Butler Matrix also can do beam steering. The main lobe position, when the input port (from first until eighth port) of Butler Matrix is supplied, leads to 50°, 250°, 80°, 300°, 40°, 310°, 60°, and 310°. Both antenna and Butler Matrix are implemented using FR-4 epoxy as the substrate. While in simulating the Butler Matrix, it uses two different substrates there are FR-4 epoxy and Duroid (RT 5880) to compare the performance.