Studies on the Equivalent Circuit of the Excitation to a Cavity-Backed Slot Antenna

In this paper, an equivalent circuit is newly described for a cavity-backed slot antenna considering the feeder and the slot element. The slot antenna has employed an electromagnetic coupling, so no solder or conductive adhesive is used. The slot is treated as a distributed constant line with a short-circuited termination, and a tuning stub is treated as a distributed constant line with an open termination. So, the mutual inductances between the feeder microstrip line and the slot are derived into the equivalent circuit. The calculated reflection characteristics by the circuit simulation are compared with the measured ones for a fabricated antenna.