This paper presents a design of a 3-dB compact ultra wideband (UWB) coupler for a 4×4 Butler Matrix which is operating between 3 and 11 GHz frequency range. The design is using microstrip-slot multilayer technology that allows having a compact and very broad bandwidth coupler. Elliptical shaped strips that are broadside coupled by a slot in a middle common ground plane is employed in order to achieve UWB performance. The device is fabricated on 0.8-mm thick FR4 substrates that occupy the dimension of 30×15 mm. A good performance over UWB frequency range from 3 to 11 GHz is verified experimentally.