Two-Dimensional Pattern-Reconfigurable Cross-Slot Antenna With Inductive Reflector for Electromagnetic Torso Imaging

摘要

A wideband and low-profile cross-slot pattern reconfigurable antenna for electromagnetic imaging systems is proposed. The antenna is designed to cover the human chest area with steerable unidirectional radiation patterns at 0.7-0.9 GHz. The antenna is comprised of a corrugated cross-slot as the main radiator, and four parasitic slots with four p-i-n diodes operating as reflectors. An embedded feeding network with six p-i-n diodes is used to feed the main slot and switch the feeding path to modify the direction of the radiated beam (vertical/horizontal). In addition, an inductive mesh-grid surface is used to reduce the back lobe and enhance the operating frequency bandwidth. The antenna dimensions are 0.8 lambda(0)x0.8 lambda(0)x0.8 lambda(0) (where lambda(0) is the wavelength of the lowest frequency operation). By turning the parasitic slot p-i-n diodes to ON/OFF modes, the main beam can be steered along five distinctive positions at 0 degrees, and at +/- 30 degrees in two perpendicular planes. The antenna achieves a peak gain of 9 dBi at 0.8 GHz with 1 dB gain variations over the band of operation with a peak front-to-back ratio of 20 dB.