LAUSR

Abstract This paper describes a compact omnidirectional antenna on a cylindrical substrate for possible application to indoor wireless communication systems operating at 18 GHz. The proposed antenna consists of nine exponentially tapered substrate integrated waveguide (SIW) H-plane horns at an angular separation of 40° from each other. A pair of metallic vias has been introduced between the horns to obtain satisfactory reflection loss. The proposed structure is symmetrical and is excited by a central probe feed. This symmetry brings about equal electric field distribution in all the horns, which leads to an omnidirectional pattern with appreciable gain (9.5 dBi in simulation). A fractional bandwidth (FBW) of 0.95% has been obtained at the resonant frequency. The design has been fabricated and tested against simulated data, wherein good agreement has been observed. The proposed structure is of low profile having a diameter 80 mm (4.8 λ 0 ) and height 0.5 mm (0.029 λ 0 ).