A Filtering Antenna With High Frequency Selectivity Using Stacked Dual-Slotted Substrate Integrated Cavities

In this letter, the stacked dual-slotted substrate integrated cavities (SICs) are proposed to achieve a filtering antenna. The dual-slotted SIC shows dual-mode behavior (quasi-dual-slot mode and quasi-cavity mode), which can achieve multiorder response with fewer SICs. Furthermore, the antenna exists at two frequencies at which the electric field has opposite horizontal component (Ex) near each slot. Thus, two radiation nulls can be obtained to enhance the frequency selectivity. The frequencies of the radiation nulls and the dual modes can both be controlled to some extent by the distance between the slots. For demonstration, a prototype at 9.65 GHz is designed with the fractional bandwidth of 9.1%, the gain of 7.2 dBi, and the frequency selectivity of 0.70.