Isolation Enhancement in Dual-Band Microstrip Antenna Array Using Asymmetric Loop Resonator

This letter presents the design of a wideband decoupling element for mutual coupling reduction in microstrip antenna arrays. The proposed decoupling unit cell consists of an asymmetric loop resonator with a coupled microstrip line for wide stopband characteristics from 2 to 5 GHz. The bandgap characteristic of the decoupling element is analyzed, and the results are presented. Furthermore, the resonator is deployed in a two-element dual-band microstrip antenna array, and mutual coupling reduction is demonstrated. The decoupling unit cell has a lateral dimension of 2.84 mm and hence enables the packing of antenna elements in very close proximity with reduced mutual coupling. The proposed solution offers additional isolation greater than 15 dB in a V-slot loaded dual-band antenna with edge-to-edge element spacing of 0.057 λ
_o
. The prototype dual-band antenna array with decoupling element is fabricated, and the simulation results are validated using experimental measurements.