A Compact Wideband Waveguide Filtering Antenna with Transmission Zero

Abstract

This letter describes the design of a compact, wideband waveguide filtering antenna with a transmission zero (TZ) in the upper stopband. A novel frequency-variant coupling (FVC) network that provides a TZ in addition to the pole is used to achieve compactness and higher selectivity. The position of the TZ can be changed in the upper stopband by altering the physical parameters of the proposed FVC. The radiating waveguide aperture is matched to the real admittance of the generator over a wide bandwidth by utilizing coupledresonator theory. This leads to a wide fractional bandwidth of 23%, along with a TZ at the upper stopband. The filtering antenna has been manufactured using metal 3-D printing to achieve low manufacturing costs and light weight. The measured results are in good agreement with the simulated ones, which shows the feasibility of the proposed FVC structure for the design of the compact waveguide filtering antenna with a TZ.