Silicon-Micromachined Subterahertz Frequency Beam-Steered Dual-Port Array Antenna

This article presents an unbalanced-fed silicon micromachined dual-port dual-line antenna array. The radiation pattern of the antenna array can be steered in the E-plane by sweeping the frequency and can be switched between a broad and a notched beam by exciting the ports with in-phase or out-of-phase signals. The antenna is designed for and implemented by silicon micromachining. Each single-line subarray consists of #8 antenna apertures in which the field amplitude is tapered in the H-plane, and the phase imbalance of unbalanced power dividers is minimized by integrated delay sections in the feed network. The measured return loss of the antenna is better than 10 dB from 220 to 295 GHz for both input ports (29.1% fractional bandwidth). The antenna prototype is designed for 40 degrees of beam steering in the E-plane (scanning speed of 4 degrees/GHz) by sweeping the frequency from 238 to 248 GHz. The measured sidelobe level of the broad beam in the H-plane is better than 18.5 dB, and the measured depth of the notched beam is better than 22.5 dB in the entire scanning range. In addition to the dual-port dual-line antenna array, a single-line 1 x 8 antenna array is also implemented for reference measurement purposes. The measured return loss of the single-line antenna array is better than 10 dB from 220 to 314 GHz (35.2% fractional bandwidth), and its measured sidelobe level is between 18 and 21.3 dB in the H-plane from 220 to 280 GHz. Besides, the simulation data and the measurement results are in excellent agreement.