A Cancelling-Blocking structure for decoupling of microstrip antenna array

In this work, a cancelling-blocking structure (CBS) for decoupling of microstrip antennas was proposed, which can reduce the coupling between arbitrary elements of a one-dimensional E-plane antenna. Results demonstrate the optimized active VSWR and improved radiation efficiency. The cancelling-type decoupling structure consists of a plurality of electrically small metal sheet arrays printed on the dielectric above the antenna. The blocking-type decoupling structure means that each element uses independent dielectric and ground plane to cut off the coupling current propagation path. Firstly, the decoupling principle of the cancelling-type decoupling structure was deduced, and the decoupling conditions were obtained. Then, the mechanism of the surface wave in the antenna array was qualitatively analyzed, and the applicable conditions of the blocking-type decoupling structure were deduced. To verify the proposed structure, a 1×8 E-plane antenna with the designed CBS was modeled. Simulation results manifested that a mutual coupling reduction of more than 10 dB in 1.2-1.3 GHz was achieved, and the active VSWR was below 2.0 over the range of ±60° scan angle.