An Analysis of the Accuracy of the Added Length De-Embedding Methods for Coaxial to Waveguide Adapters in the X-Band

This paper assesses the accuracy of the “added length method” (also known as port extension or channel offset) for de-embedding coaxial-to-waveguide transitions in the X-band, comparing it to full waveguide calibration on both Keysight and Rohde & Schwarz VNAs. The study examines the trade-offs between cost and measurement accuracy, highlighting the feasibility of using these mathematical correction techniques in the absence of dedicated waveguide calibration kits or full S-parameter characterizations of the transitions. The analysis concluded that when using coaxial-to-waveguide transitions the added length method produces accurate results for transmission measurements only.