Frequency Estimation Method for Wideband Microwave Camera

Microwave camera is a passive focal plane microwave imaging system which is used for large-scale, wideband electromagnetic interference (EMI) imaging. Microwave camera images the EMIs with their amplitude and location by the reflector and sensor array, like taking a photograph. This camera, however, only receives the power density of the EMIs within a wideband and the frequency information is aliased and abandoned. To address this issue, in this article, we propose a frequency estimation method to recover the frequency of the wideband EMI from its amplitude image without a need to add new hardware. For the developed imaging system, the proposed method realizes the frequency estimation in the 3-6-GHz frequency range with a resolution of 100 kHz consistently in most of the central part of the field of vision (FOV). Our proposed method is also applicable to other passive imaging applications such as passive millimeter radar imaging and infrared imaging, to extract the related information of the detected objects.