Microstrip line fed slot, slot-coupled patch antennas, and mutual coupling study in array applications

Abstract

Two examples of circularly-polarized slot and slot-coupled patch antennas fed by a microstrip line are designed at 4.8 GHz, a dual slot-coupled circular patch (DSCCP) antenna and an monofilar Archimedean spiral slot (MASS) antenna. The mixed potential integral equation (MPIE) is applied to investigate the behavior of these antennas. Comparing these two antennas, the former offers better radiation efficiency but the latter has a wider VSWR and axial ratio bandwidth. Also the mutual coupling study of the S parameters and radiation pattern is conducted for a two-element dual slot coupled circular patch subarray. It is observed that the axial ratio is greatly influenced by the adjacent element. Only at certain inter-element spacing, a less than 1 dB axial ratio is obtained.