A low profile antenna array for UWB radar antenna applications is disclosed. It may be used as a mid-range receiving antenna array (RXM) or as a mid-range transmitting antenna array (TXM). In some embodiments, the RXM or the TXM may include a plurality of radiation patch elements formed on a top layer of a printed circuit board (PCB), a distribution feeding network in the mid-layer of the PCB having a patch array, and a serial feeding arrangement from a λ/4 coupling slot to each feeding patch. This antenna may have a desirable large frequency bandwidth with relatively flat antenna gain over a frequency range from 22 GHz to 26.5 GHz. In addition, sidelobe levels for the elevation patterns may be below −20 dB. Other embodiments are disclosed and claimed.