High-Efficiency Cavity-Backed Filtering Slot Antenna Array with Simplified Feeding Structure

A high-efficiency metal-cavity slot antenna array with filtering response and simple feeding structure is proposed. Two resonant cavities operating at
$\mathbf{TE}_{\mathbf{101}}$
mode is cascaded together to produce a filtering performance. As the
$\mathbf{TE}_{\mathbf{101}}$
cavity mode has unidirectional electric field distribution, the radiating slots are simultaneously excited without the introduction of the power dividers. Finally, a second-order
$3\times 3$
filtering slot array is designed and simulated by using the design method of coupling matrix. Final simulation shows that the designed antenna has an operating bandwidth of 3.5% with good filtering performance and high efficiency.