OPTIMIZATION OF MICROMACHINED MILLIMETER-WAVE PLANAR SILICON LENS ANTENNAS WITH CONCENTRIC AND SHIFTED MATCHING REGIONS

This paper presents a study of planar silicon lens antennas with up to three stepped-impedance matching regions. The effective permittivity of the matching regions is tailor-made byetching periodic holes in the silicon substrate. The optimal thickness and permittivity of the matchingregions were determined by numerical optimization to obtain the maximum wideband aperture efficiencyand smallest side-lobes. We introduce a new geometry for the matching regions, referred to as shiftedmatching regions. The simulation results indicate that using three shifted matching regions results intwice as large aperture efficiency as compared to using three conventional concentric matching regions.By increasing the number of matching regions from one to three, the band-averaged gain is increasedby 0.3 dB when using concentric matching regions, and by 3.7 dB when using shifted matching regions,which illustrates the advantage of the proposed shifted matching region design.