A high frequency coupler is disclosed that is configured for grid array-type surface mounting. The coupler includes a monolithic base substrate having a top surface and a bottom surface. A first thin film microstrip and a second thin film microstrip are each disposed on the top surface of the monolithic base substrate. Each microstrip has an input end and an output end. At least one via extends through the monolithic base substrate from the top surface to the bottom surface of the monolithic base substrate. The via(s) are electrically connected with at least one of the input end or the output end of the first microstrip or the second microstrip. The coupler has a coupling factor that is greater than about −30 dB at about 28 GHz.