Slot loaded folded half-mode substrate integrated waveguide antenna for wideband applications

In this work, a new folded half-mode substrate integrated waveguide (HMSIW) cavity has been conceived to design a wideband high gain slot antenna. Initially, a rectangular (90 mm x 10 mm) HMSIW, loaded with two identical slots at two ends, is designed to operate in the X-band. Thereafter, it has been folded to form a U-shape considering the possibilities of staggering between the closely spaced operating bands to realize a true wideband printed antenna with a higher gain. The proposed antenna, thanks to the excitation of the staggered higher-order modes in the folded slot-loaded rectangular HMSIW, exhibits an excellent wideband performance of 48.44% (9.15-15 GHz) with a maximum peak gain of 9.25 dBi. This low profile structure with an overall dimension of 0.91 lambda(0) x 0.91 lambda(0) x 0.047 lambda(0) is printed on a single layer double-sided RT/duroid (R) 5880 substrates with a circular shaped ground plane. The design concept has been validated through impedance and radiation pattern measurement of the fabricated prototype revealing a good agreement with the simulated results.