Dual-mode Cavity Antenna with Filtering Response

In this paper, a compact filtering antenna is proposed at 26 GHz for millimeter wave applications. This antenna is composed of a full-metal cavity loaded with two symmetrical slots. By properly feed the antenna, TE
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cavity mode and slot mode can be excited simultaneously, obtaining a dual-mode performance for wideband property. Besides, by adjusting the position of the slots, one radiation null can be well produced at upper stopband due to the coupling formed between the cavity mode and slot mode. Additionally, another radiation null is accompanied with TE
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mode, further improving the out-of-band rejection at upper stopband. Finally, the proposed antenna is fabricated by 3D printing technology, and the measured results agree well with the simulated ones. Measurement results show that a wide bandwidth of 21.6% covering from 23.6 to 29.3 GHz is obtained, with a maximum gain of 8.7 dBi. Besides, two radiation nulls can be well observed at upper stopband. The overall properties show that proposed antenna is a good candidate for millimeter wave applications.