Further Investigations into Connection Repeatability of Waveguide Devices at Frequencies from 750 GHz to 1.1 THz

This paper describes some further investigations into the connection repeatability for waveguide devices in the WM-250 (WR-01) waveguide size over the recommended frequency range of 750 GHz to 1.1 THz. This work follows previous work on this subject that was presented at the 82nd ARFTG conference in November 2013. As with the earlier investigation, three devices have been investigated - an offset short-circuit, a flush short-circuit, and a near-matched load. These devices can be used as calibration standards for Vector Network Analyzers (VNAs), and so can be found in VNA calibration kits. On this occasion, the aperture of each device was inverted (i.e. rotated through 180°) between the repeated disconnection and re-connection of the device to the VNA test port. This provides an experimental evaluation of the effect of the imperfect position of the device's flange alignment pins and holes. As before, the repeatability of the measurements is assessed using statistical techniques, in terms of the experimental standard deviation in both the real and imaginary components of the complex-valued linear reflection coefficient. The results obtained during this investigation are compared with the results obtained from the previous investigation (where flange inversion was not included as part of the disconnection and re-connection procedure for the devices).