Half-mode substrate integrated waveguide omnidirectional slot antenna

A half-mode substrate integrated waveguide (HMSIW) omnidirectional slot antenna is proposed for the first time by integrating four narrow wall radiating slot antenna elements and a four-way power divider. The slot antenna element realises energy radiation from the open side of the HMSIW by etching several pairs of transversal slots both on the upper and the lower surfaces of the HMSIW and alternately arranging the slot pairs. A novel HMSIW four-way power divider is achieved to feed the slot antenna elements by loading four big metallic vias to guide the microwave into the HMSIW branches. This omnidirectional slot antenna has an efficiency of 86%, a gain of 5.8 dBi and an out-of-roundness of ±1.5 dB at 3 GHz, which makes it a good candidate for wireless communication applications.