D-Band Wideband Air-Filled Plate Array Antenna With Multistage Impedance Matching Based on MEMS Micromachining Technology

A wideband air-filled plate array antenna with multistage impedance matching operated in $D$ -band is proposed in this article. To achieve the wide bandwidth, three stages of impedance matching are introduced in the $2\times 2$ subarray, including the step-profiled horn element, the step-profiled power divider cavity with two resonant points, and a modified E-plane bend transition. The integrated step-profiled horn with simple configuration can realize broadband matching. Wideband T-junctions are combined together to form a corporate feeding network. Essential matching pins are introduced to break through the upper bandwidth restriction of the feeding network. In addition, the square aperture shape of the horn element and the air-filled feeding structure contribute to the high radiation efficiency of the proposed array. To satisfy the fabrication tolerance, the MEMS micromachining technology with a high etching precision is utilized. The experimental results show a wide 1 dB down gain bandwidth of 23.54%. The maximum gain is 33.24 dBi and the peak efficiency is 70.91%.