Modelling of wideband inter-element EM coupling in 2D space-time frequency domain

Wideband antenna arrays having elements spaced in a uniformly-spaced configuration are increasingly common in electromagnetic (EM) beamformers for radio-astronomy, pulsar science, radar, and wireless communications. EM coupling between elements cause changes to the polar pattern and lead to increased noise in the system. Traditionally, scattering (S) parameters are used to measure of coupling. However, S-parameter measurements by themselves do not lead to a complete view of the effects of coupling. In this work, the EM coupling is modelled as a 2D space-time phenomena using well-established theory in the multi-dimensional signal processing area. Measured S-parameters obtained from a vector network analyzer (VNA) can be used for de-embedding coupling effects from measured beamformer performance. Here, an overview of the proposed method is provided, followed by closed-form equations that express EM coupling between neighbouring elements in an array in terms of S-parameters and reflection coefficients. The proposed equations are verified using A) FEKO for EM simulations and B) Agilent´s Advanced Design System (ADS) for S-parameter simulations. Both software models are found to agreewith the proposed equations, thereby confirming their validity at the simulation level. Experimental verification is left for future work.