Circular Aperture Antenna With Conical Beam

A novel circular aperture antenna with a conical beam fed by a coaxial line is presented. Three printed ring slots have been employed as the transition between the coaxial line and the open-ended circular waveguide. Through optimal design, the gain of 8-9.3 dB and elevation angles of 24°-31° have been achieved in the -10 dB impedance bandwidth of 12.2% at the center frequency 35 GHz, respectively. A rigorous analysis of the antenna using the mode-matching method is conducted. Good agreement has been observed between simulated results and measured ones.