A circuit model to compute impedance of electromagnetically coupled ring antenna

In the present work a new numerical model using, the cavity model along with circuit theory has been used to calculate input impedance of a ring resonator loaded by a microstrip line. This type of model has not been investigated yet. A ring resonator is fed by a narrow microstrip line underneath the ring. The proposed structure is analyzed and the input impedance is computed. The computed results are then compared with simulation. This model is a simple method to predict the input impedance of a loaded ring resonator by a microstrip line. In this proposed model a ring is used for the purpose of radiation in its fundamental mode.