A 38 dB Gain, Low-Loss, Flat Array Antenna for 320–400 GHz Enabled by Silicon-on-Insulator Micromachining

Two high-gain flat array antenna designs operating in the 320-400 GHz frequency range are reported in this article. The two antennas show the measured gains of 32.8 and 38 dBi and consist of a 16 × 16 (256) element array and a 32 × 32 (1024) element array, respectively, which are fed by a corporate H-tree beamforming network. The measured operation bandwidth for both antennas is 80 GHz [22% fractional bandwidth (FBW)], and the total measured efficiency is above -2.5 dB and above -3.5 dB for the two designs in the whole bandwidth. The low measured loss and large bandwidth are enabled by optimizing the designs to the process requirements of the silicon on insulator (SOI) micromachining technology used in this article. The total height of the antennas is 1.1 mm (1.2 λ at the center frequency), with sizes of 15 mm × 18 mm and 27 mm × 30 mm for both arrays. The antennas are designed to be directly mounted onto a standard WM-570 waveguide flange. The design, fabrication, and measurements of eight prototypes are discussed in this article and the performance of the antennas compared to the simulated data, as well as manufacturability and fabrication repeatability are reported in detail.