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A compact broadband circularly polarized (CP) magnetoelectric dipole antenna array (ME-DAA) based on a single-layer ridge gap waveguide (GW) is proposed in the Ka-band. The antenna array consists of a dielectric layer of printed ME-DAA and a single-layer metal corporate network using GW. The U-shaped coupling slot parallel to the feeding ridge is used, avoiding the complexity of conventional cavity layers. The matching section in the feeding ridge is adopted to achieve wideband impedance matching. Besides, by chamfering the classic ME-dipole patches, the axial ratio (AR) bandwidth of the antenna is improved. Meanwhile, a ring of metal vias is loaded around each unit to enhance the isolation between array elements, further broadening the total array bandwidth. An $8 \times $ array prototype is manufactured. The measured impedance bandwidth and AR bandwidth are 22.6% (26.7–33.5 GHz) and 20.2% (26.7–32.7 GHz), respectively. The sidelobe levels of radiation patterns are better than −12.2 dB. The peak radiation and aperture efficiencies are about 93% and 87%, respectively. And the peak realized gain is up to 27.8 dBic at 31.6 GHz.

This letter proposes a wafer-level packaged (WLP) single-chip sequential rotation Crossbar (SR-Crossbar) RF MEMS switch matrix, which has been fabricated and measured. Optimizations are conducted on switch units, including electrically connected seal ring design, DC-RF common ground design, and integrated cross design. The designs effectively simplify the fabrication process and improve compactness of the matrix. Measurements demonstrate that insertion loss of the longest path in this ${8}\times {8}$ SR-Crossbar RF MEMS switch matrix maintains better than -19dB within 0-26.5GHz range. Return loss is better than -18dB, and crosstalk and isolation are both better than -20dB. To the best of the authors’ knowledge, this is the first fabricated single-chip large-scale RF MEMS switch matrix with wafer-level packaging, which exhibits significant performance advantages compared to relevant works.