An Annular Waveguide Slot Antenna

In this letter, an introduction to a novel annular slot cut on the broad wall of an annular waveguide is presented. An equivalent circuit model is suggested for the structure based on its similarity to the rectangular slotted-waveguide case. Full-wave analysis is performed using two numerical commercial software packages and the circuit model expectation is verified. A single slot annular waveguide slot antenna (AWSA) is designed and fabricated based on the derived model and impedance and radiation pattern measurement results are provided and compared with those of simulation and theory. A discussion on possible circular array combination of the AWSA is presented finally.