ANALYSIS AND APPLICATION OF A 2-PORT APERTURE-COUPLED MICROSTRIP ANTENNA

A two-port aperture-coupled microstrip antenna was analyzed using the method of moments together with a mixed potential integral equation (M PIE), The antenna contains two microstrip-line ports (i.e., a feeding port and a coupling port), The field coming from one microstrip line o n the circuit layer is fed into the patch through an aperture on the g round plane, Part of the field is then coupled back to a second micros trip line through another aperture on the same ground. The influences of the stub lengths, along with the positions and sizes of the apertur es, on the coupling power and the resonant frequency were investigated . As an application, a feedback antenna oscillator was designed using the present structure where the antenna served not only as a radiator, but also as a feedback resonator. The oscillation was stable and with a clean spectrum at the frequency of 9.79 GHz, which was only 0.2% di fferent from the design one. An effective isotropic radiated power (EI RP) of 39 mW was achieved. The measured cross-polarized fields were at least 15 dB lower than the copolarized ones.