Gain optimization in RLSAs with lossy substrates by the slot coupling control

This paper studies the operation of Radial Line Slot Antennas (RLSAs) having lossy substrates as waveguide-filled materials. Based on the operating mechanism of the conventional lossless RLSAs, new formulations to optimize the antenna gain are derived theoretically and partly confirm by measurement. As the result, at 32GHz, a 90cm diameter RLSA with material loss factor of 0.014∼0.018dB/mm, about 0.25∼0.35dBi gain enhancement is expected by using newly defined coupling.