The design evolution and investigation of a semi-elliptical patch antenna having a slot in the ground plane is discussed in this paper. The proposed prototype delivers extraordinarily wide impedance bandwidth ranges from 10.5GHz to 40.0GHz and beyond. In the design of this antenna, a semi-elliptical patch is fed by a tapered feed line, which is backed by a squareshaped ground plane that is slotted with an elliptical-shaped slot. The antenna is small in size, with a dimension (L*W*h) of 39.0mm × 39.0mm × 1.59mm and gives desired radiation characteristics including the stable radiation pattern. The gain value within the impedance bandwidth region is almost steady and positive. The antenna performance is optimized with CST Microwave Studio 2017. The designed antenna will be a useful candidate for the recent 5G technology as this technology requires a very high bandwidth with sustained gain to transmit the data at a high speed.