In this paper. we propose a novel Half Mode Substrate Integrated Coaxial Line (HMSICL) cavity fed monopole antenna at 28 GHz. A SICL cavity is bisected along its symmetric magnetic wall (PMC) to create an open-ended Half Mode SICL (HMSICL) cavity. The proposed HMSICL cavity is used to excite a tapered monopole antenna to radiate in endfire direction with a gain of 6. https://seisukeknifes.shop/product-category/name-engraving-service/