Simulation, parametric study and fabrication of slow wave structure for use in Radial Line Slot Array (RLSA) Antennas

Radial line slot array (RLSA) antennas are a type of high-efficiency plane array antenna used to generate circular polarization. In these antennas, the second-floor wave-guide is filled with a dielectric material to eliminate the grating lobes caused by the array of structures. All input power to the antenna must pass through a confined space that includes dielectric, air, and metal. This space has corners where the intensity of the electric field will be very high and, therefore, at high powers, will reduce the power transmission capacity of the antenna. For this reason, instead of using a dielectric in the space between two wave-guides, a slow radial wave structure is used. In this paper, first, a mathematical analysis of slow-wave structure is performed based on the Fluke theory. Next, a slow-wave structure is designed, simulated, and optimized for use in a 10.2 GHz Radial line slot array antenna.The simulation results showed that the minimum reflection coefficient is -20 dB, and its bandwidth is 251 MHz. Finally, a prototype of the simulated antenna was constructed using the proposed structure. Antenna power analysis showed that the minimum tolerable antenna power is 625 MW.