Scalable Multiport Antenna Array Characterization With PCB-Realized Tunable Load Network Providing Additional "virtual" VNA Ports

• Published in: IEEE antennas and wireless propagation letters pp. 1 - 5
• Main Authors: Tapie, Jean, Hougne, Philipp del
• Format: Journal Article
• Language: English
• Published: IEEE 2025; Institute of Electrical and Electronics Engineers
• Subjects: Ambiguity; Antenna arrays; BD-RIS; Calibration; Correlation; Engineering Sciences; Freeports; printed circuit board; Resonant frequency; Scattering; scattering matrix estimation; spectral correlation; Switches; Transmission line matrix methods; Transmission line measurements; tunable load network; Vectors; virtual VNA; VNA extension kit; Electrical engineering; Computer science; Engineering; Scalability; Database; Electronic engineering; Materials science; Telecommunications; Antenna array; Characterization (materials science); Nanotechnology; Antenna (radio)
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2025.3579891

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><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.