A Miniaturized Cavity-Backed Slot Third-Order Filtering Antenna Using Multiple Mode Resonator

A novel miniaturized cavity-backed slot filtering antenna is presented. The antenna consists of a cavity with three metallic cylinders. The cavity filter of the proposed multiple-mode resonator filtering antenna has only one cavity compared to a traditional 2nd-order coaxial filter, with an additional resonance mode within the passband. Moreover, two pairs of capacitive stubs, are used to achieve a third-order-filtering response. The proposed antenna operates at 8.1 GHz central frequency with a fractional bandwidth of 4.9% (S
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less than -10 dB). The E-field distribution of the proposed antenna is plotted to further understand its filtering mechanism. The simulation results reveal that the proposed antennas exhibit good radiation characteristics in the passband and frequency selectivity as well, and effectively reject the out-of-band frequencies.