Effect of Reflection-Termination in Out-of-Use Ports of Rotating Mode Excitation Planar Circuit for Radial Line Slot Antenna by using a Quasi-Coaxial Feeding

We have proposed the microstrip-line (MSL) to radial-line transformer for rotating mode excitation by using a quasi-coaxial structure. When out-of-use ports are matched-terminated, the characteristic of the transformer was investigated in the previous study. In this paper, the characteristic is calculated when out-of-use ports are terminated with reflectors, which correspond to truncated MSLs for practical use. The total reflection of -36.8 dB at 60 GHz is obtained. The calculated amplitude and phase deviation in the circumferential direction in radial waveguide are 2.16 dB and 13.3 degrees, respectively.