WiFi-based imaging for ground penetrating radar applications: fundamental study and experimental results

As a fundamental research step for subsurface target imaging by passive ground penetrating radar, some simulation and experimental results of passive bistatic radar imaging for short-range targets by using IEEE 802.11 Wireless Fidelity (WiFi) wave as the source of illumination have been presented. As the WiFi signal only penetrates shallow layers and yet lacks bandwidth for high resolution subsurface structure mapping, the interrogation of cooperative targets with the passive bistatic radar approach is demonstrated. This strategy is achieved by inserting surface acoustic wave (SAW) delay lines acting as dedicated reflectors allowing for subsurface tagging (identification) or sensing (temperature measurement) through the fine measurement of echo delays. Experimental results show that short-range targets, such as cars and metallic plates located within 10 m, can effectively be detected and imaged. The response of the SAW delay lines can also be well probed.