A 140 GHz High-Efficiency Slotted Waveguide Antenna Using a Low-Loss Feeding Network

This letter proposes a 140 GHz high-efficiency slotted waveguide antenna with a low-loss feeding network. The feeding network provides the same-magnitude but alternating-phase excitations for the slotted parallel-plate waveguide (PPW) array. The alternating-phase excitations are used to implement virtual electric walls (VEWs) for replacing the physical metal walls. Hence, the antenna efficiency is improved significantly. To verify the proposed method, an 8 × 8 slot array with the proposed feeding network is designed and fabricated, which has a fractional bandwidth of 10.17%, i.e., from 132 to 146.15 GHz. Experimental results show that the radiation and aperture efficiency of the prototype can be as high as 93.4% and 73.2%, respectively. The measured antenna has a peak radiation gain of 24.59 dBi at 137.5 GHz and a flat in-band gain. The proposed antenna provides a promising solution to develop high-efficiency upper millimeter-wave and sub-terahertz (THz) applications.