Scalable Multiport Antenna Array Characterization With PCB-Realized Tunable Load Network Providing Additional “Virtual” VNA Ports

We prototype a PCB-realized tunable load network whose ports serve as additional “virtual” VNA ports in a “Virtual VNA” measurement setup. The latter enables the estimation of a many-port antenna array's scattering matrix with a few-port VNA, without any reconnections. We experimentally validate the approach for various eight-element antenna arrays in an anechoic chamber in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$700-900$</tex-math></inline-formula> MHz regime. We also improve the noise robustness of a step of the “Virtual VNA” post-processing algorithms by leveraging spectral correlations. Altogether, our PCB-realized VNA Extension Kit offers a scalable solution to characterize very large antenna arrays because of its low cost, small footprint, fully automated operation, and modular nature.