Group Delay Measurement For Satellite Payload Testing
Authors: A.C. Newell, S.F. Gregson, P. Pelland, D. Janse van Rensburg
Publication: AMTA 2017
Copyright Owner: NSI-MI Technologies
In this paper, we present a method for measuring antenna group delay (GD) in a planar near-field range. The technique is based on a set of three antenna pairs, measured sequentially, from which the insertion phase of the measurement system and the near-field probe can be resolved. Once these parameters are known, insertion phase for the device under test (that is to say a Tx or Rx antenna) can be measured and GD calculated as the negative frequency derivative of the insertion phase with respect to frequency. An added complexity in the case of a near-field measurement is the near-field probe is in close proximity to the device under test, does not satisfy the far-field condition. We also show that group delay can be extracted from a single near-field measurement point in the antenna’s aperture plane, leading to significant test time savings. Measured results are presented and discussed.