Wideband Substrate Integrated Waveguide Antenna for Electromagnetic Torso Imaging System

A body-matched wideband directional Substrate Integrated Waveguide (SIW) antenna is presented for torso imaging systems. The proposed antenna comprises a rhombus-shaped patch on the top layer fed by a coaxial cable from the bottom layer. This patch is then surrounded by vias to achieve wideband impedance matching. Then, a quarter-wavelength rectangular-shaped slot is etched on top of the patch to enhance the impedance matching. The structure is printed on Rogers TMM 13i substrate. The results indicate that the designed antenna has three resonance frequencies at 0.65, 0.87, and 1.10 GHz. The antenna covers a wide frequency band from 0.58 to 1.17 GHz (67.4 % fractional bandwidth). Moreover, the antenna occupies 112×112×12.7 mm
³
, equaling 0.21×0.21×0.02 $\lambda _0^3$, where is the wavelength at the lowest working frequency. The study of wave penetration inside the torso indicates that the power flow intensity in the middle of the torso is -20.10 dB.