Internally Excited Fabry-PÃ\x89rot Type Cavity: Power Normalization and Directivity Evaluation

This letter presents a new approach to analyze Fabry-PÉrot cavities excited from their inside by electromagnetic waves. While Fabry-PÉrot cavity antennas found in literature use often the magnitude of the transmission coefficient to determine the antenna directivity, the proposed approach suggests a new strategy that uses a normalized transmission coefficient, which is derived by using a transmission line model and by considering the available power from the source. Furthermore, a new analytical expression is also proposed for evaluating the directivity. The obtained results are presented and compared to experimental results reported in literature.