Compact and Wide-Beamwidth Waveguide Filtering Antenna With Two Transmission Zeros

A compact dual-mode dielectric resonator (DMDR)loaded evanescent-mode waveguide filtering antenna with twotransmission zeros (TZs) is presented. The design methodologyconsists of using a pair of degenerate transverse magnetic modes ofellipsoid DMDR alongwith source-to-aperture coupling to generatetwo transmission poles and two TZs-one TZ at each side ofthe passband-in the filtering response. The prototype of filteringantenna is designed to operate at \boldmathf0=8.15GHz with a10 dB return-loss bandwidth of 1.35% and an appreciable realizedgain (RG) of 4.8 dBi. The two TZs (\boldmathfTZ1=7.9GHzand \boldmathfTZ2=9GHz) are responsible for providing sharpselectivity with a low shape factor value of 1.6 at 10/3 dB. Moreover,the proposed small-volume (0.055 lambda 30,where lambda 0is the free spacewavelength atf0) filtering antenna radiates with a wide beamwidthof118 degrees in E-plane. The temperature stability analysis of filteringantenna results in low drift values of 2.08 ppm/degrees Cand 46.1 ppm/degrees Cforf0and RG, respectively, when temperature varies from-25 degrees Cto 75 degrees C. Finally the filtering antenna is fed by a standardpropagating waveguide, making it apt for high-power applications