Improving Compact Short Backfire Antenna Gain and Cross-Polarization Using Choke and Ring Cavity Loading

Abstract

We present two designs that improve the gain and cross-polarization performance of the waveguide-fed short backfire (SBF) antenna by introducing a choke (SBF-2) and by loading the cavity with a metallic ring feature (SBF-2-Ring). A series of parametric simulation studies on antenna dimensions provides information on how to improve the antenna gain and cross-polarization performance while simultaneously extending the impedance bandwidth. For SBF-2, the peak gain was 16.6 dBi, the minimum cross-polarization ratio was −23.8 dB, and the maximum impedance bandwidth was 27.3%, with a gain bandwidth of 19.2%. For SBF-2-Ring, the peak gain was 15.8 dBi, the minimum cross-polarization ratio was −29.1 dB, and the maximum impedance bandwidth was 43.5%, with a gain bandwidth of 31.8%. The concepts were verified by designing, fabricating, and testing two prototypes in the microwave C-band. Excellent agreement between simulation and measurement was achieved. The measured gain for SBF-2-Ring was >14 dBi for 4.7-6.2 GHz and the worst case cross polarization in the diagonal plane was <−22 dB for 5.3-5.8 GHz. Cross-polarization in the principal planes has significantly greater bandwidth and the worst case analysis is presented to give limitations on the performance.

Gain and Bandwidth Enhancement of 3D-Printed Short Backfire Antennas Using Rim Flaring and Iris Matching

“…The weight and cross-polarization ratio of these designs were not disclosed, hence these characteristics were not included. The gain values of the flared antenna are similar to those of the antennas mentioned in [ 20 , 22 , 23 ]. However, the impedance bandwidth of the flared antenna is much wider than that of the above-mentioned antennas.…”

“…This study aims to further increase the gain and bandwidth of the antenna presented in [ 4 , 20 ] while maintaining its cross-polarization ratio. The flared SBF antenna shown in Figure 1 consists of several parts and is fed by a waveguide feed because of its high gain and high-power handling abilities.…”

“…The conventional SBF antenna consists of only four parts: the main reflector, the rim, the sub-reflector, and the feed antenna. The choke portion was included in the work presented in [ 4 , 20 ] as a way of increasing the gain. In this study, to further increase the gain, we decided to flare the upper diameter of the antenna’s rim, similar to the design of the horn antenna.…”

Mass Reduction Techniques for Short Backfire Antennas: Additive Manufacturing and Structural Perforations

“…The proposed SBF antenna designs are based on the improved SBF antenna presented in [3] and shown in Figure 1a. It is a modified waveguide-fed SBF antenna with a choke.…”

“…Traditional SBF, reflector, and horn antennas can range from 500 g [3] to 8 kg [4] or even higher in weight, depending on the type and size of the antenna. In remote sensing applications, where antennas are installed on drones with weight restrictions, or in space applications, where the entire system weight significantly influences launch costs, heavy-weight antennas can pose a challenge.…”