Stub-Loaded Sub-Terahertz Wideband Antenna Design and Measurement

This paper presents a wideband dual-fed/dual-polarized sub-terahertz (THz) array antenna design and D-band measurement system setup. The designed array is 4x1 linear array operating from 136 to 148 GHz. The array is fed by vertically constructed corporate feeding network, and it is fabricated through printed circuit board (PCB) using modified semi-additive process (mSAP). For wideband impedance matching of the antenna element, stub-loaded proximity coupled stacked patch antenna is introduced. By employing two or more open/short stubs on vertical via transition of the proximity coupled line, wideband input impedance matching is achieved, and these stubs can be easily integrated into the antenna element without increasing the element size. A customized probe station is also built to enable probing from the bottom side of the probe station. This feature is very useful for accurate measurement and characterization of antenna-in-package (AiP). To obtain true antenna and feeding network performance of the AiP, RF probing must be conducted on bump pads where radio frequency integrated circuit (RFIC) is mounted as a flip-chip. The simulated and measured bandwidth of the 4x1 linear array is over 24.3 GHz with return loss of 10 dB. The maximum gain is measured as 9.1 dBi in the proposed D-band measurement system.