Flange Effect Minimization and Antenna Isolation Improvement Using RF Choke in Slotted Waveguide Array Antenna

Abstract

In this paper, Minimization of Flange effect and antenna transmit to receive isolation improvement using RF choke in Slotted Waveguide Array antenna is presented. In slotted waveguide antenna, the mounting of waveguide to the flight vehicle is done by using a waveguide flange. The flange causes variation in the antenna Radiation pattern, and increase in Side lobe level and thereby degrading the performance of antenna. An RF Choke adjacent to the waveguide wall, is used to nullify the undesirable effects of the flange. The comparison of simulated results with and without the flange and with and without choke are presented. It is observed that the quarter wave length groove called choke, at certain distance from waveguide wall, along the length of the waveguide improves the radiation pattern, isolation and SLL, hence reduces the flange effect. It is observed that the antenna properties of slotted waveguide antenna with flange and choke approximately matches with the antenna properties of slotted waveguide antenna without flange and choke. It is observed that presence of choke also improves the Isolation from transmit to receive antenna.