Phased Array Antennas with Wide-Angle Scanning: Design of Decoupling Feeding Network

This paper presents a new approach to address the challenge of achieving wide-angle impedance matching across the entire angle sweep in phased array antennas. This approach involves the design of a novel decoupling feed network structure that compensates for the changes in the active impedance of each antenna element during angle scanning. The proposed structure includes a loop with two different paths between the antenna feed, with one path taking a sample coupling from one antenna element and canceling out the over-the-air coupling effect on the other antenna. By properly designing the length of the path to be 180 degrees out of phase, the proposed approach achieves about 20 dB mutual coupling reduction at the center frequency. The decoupling network is applied to a 4 by 4 array antenna, and full-wave simulation results demonstrate its effectiveness. Compared to conventional wide-angle matching impedances, the proposed approach is adaptable to any linear array and does not require a real state on the aperture to operate.