Design of a Wide-Band Aperture-Coupled Microstrip Antenna Array

Microstrip antenna array has the advantages of high gain, low profile, small volume, light weight, low cost and flexible conformability. While, in order to overcome the problems of narrow bandwidth and strong cross polarization of microstrip antenna, this paper designs a broadband multilayer microstrip array by adopting offset-aperture coupling feed, parasitic patch and parallel feeding network. Based on equivalent circuit analysis and simulation verification, the influence of key parameters on impedance matching of antenna element is gotten, and the optimal structure size of antenna element is obtained. An 8×8 microstrip array with 45°polarization is realized, using a masterly parallel feeding network with power equally divided. Simulated and measured results show, for the array, the impedance bandwidth with VSWR < 2 reaches 48. 8%, the gain with HPBW > 9. 2° is greater than 18 dB, the low cross-polarization level is lower than -22 dB, and it has deep zero depth and low side lobe level.