Broadband compact CPW-fed metasurface antenna for SAR-based portable imaging system

A broadband and compact coplanar waveguide (CPW) coupled-fed metasurface (MS)-based antenna for C-band synthetic aperture radar (SAR) imaging application is proposed in this article, which is consisted of 16 uniform periodic square patches performed as radiators. The CPW feeding structure gives two following functions: (1) It excites an aperture coupling slot structure underneath the center of MS patch array. (2) It acts as a ground plane for the metasurface patch units. Different slots were investigated and eventually an hourglass-shaped slot is applied to enhance bandwidth for imaging applications. A prototype with a dimension of 60 x 60 x 1.524 mm(3) (1.1(0) x 1.1(0) x 0.03(0)) operating at the center frequency 5.5 GHz (f(0)) has been fabricated and measured to verify the design principle. This antenna has a measured impedance bandwidth of 12.4% from 5.14 to 5.82 GHz, a peak gain of 9.2 dBi and averaged gain of 7.2 dBi at broadside radiation. Microwave imaging experiments using the proposed antenna have been carried out and a good performance is achieved.