A W-Band GSG Probe Fabricated by Metal Additive Manufacturing.

In this article, we present a new type of waveguide ground-signal-ground (GSG) probe for millimeter-wave (mmWave) on-wafer measurements. The proposed design integrates a GSG tip, a microcoaxial transmission line (TL), and a waveguide-to-coaxial transition in one structure. The waveguide port of the probe can be inserted into a section of the rectangular waveguide and then directly connected with the vector network analyzer (VNA). To optimize the contact force between the probe tip and the device under test (DUT), the inner and outer conductors of the GSG tip are designed to have different heights. To verify the performance of the proposed design, a W-band (75-110 GHz) prototype is fabricated based on the micrometal additive manufacturing (AM) technology. Due to the unique characteristics of AM technology, the probes can be fabricated in one piece and need no assembly, which significantly reduces the manufacturing cost and eases probe maintenance and repair. The measured results show 0.65-0.90-dB insert loss and over 15-dB return loss (RL) within the whole operating bandwidth, which validates the design mechanism and shows great potential for future economic subterahertz (THz) on-wafer measurements.