Abstract:
In this paper, a spotlight imaging system integrated with a frequency-diverse aperture is presented for security-screening applications. The spotlight imager consists of holographic metasurface antennas that can dynamically be tuned to radiate spotlight patterns allowing the extraction of high-resolution images from a constrained field-of-view (FOV). The reconfigurable holographic metasurface antennas consist of a metasurface layer used to modulate the guided-mode reference to an aperture field of interest producing the desired radiated wavefronts. The reconfigurable operation is achieved in an all-electronic manner without the need for any mechanical moving apparatus or phase shifting circuits. The spotlight aperture operates at a single frequency, 75 GHz, within the W-band frequency regime (75-110 GHz) and is used for the high-resolution identification of threat objects while the frequency-diverse aperture operates at K-band frequencies (17.5-26.5 GHz) and is used for low-resolution detection purposes. The scene to be imaged is first interrogated using the K-band aperture at low resolution and the constrained-FOV is imaged using the W-band system to achieve the identification of threat objects.
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