Measurement of Very-Near-Field Distribution of Onboard Antenna Using Scanning Optic-Induced Plasma Scattering Technology

Very-near-field distribution is valuable for evaluating antenna performance. For radio frequency (RF) onboard antennas, the very near field generally includes the responses from both the antenna and other components, making it more complex to measure. In this paper, we realize a very-near-field measurement method using scanning optic- induced scattering (SOPS) technology. The SOPS method utilized a silicon wafer attached to the onboard antenna surface as the measurement medium. A laser spot illuminates and scans across the silicon wafer surface, where the generated optic-induce plasma scatters the incident wave. A receiving antenna was applied to capture the scattered signals, allowing for the imaging of the high-resolution very-near-field distribution. A Ku-band onboard transmitting antenna module and a commercial radar were measured through coherent measurement and non-coherent measurement. Near-field distributions of different distances were observed. The very-near-field distributions clearly reveal both the antenna and chip signals. The proposed method can achieve flexible and efficient very-near-field measurement, which is promising in the electromagnetic field characterization of the onboard antenna.