A dual polarised wave-guide notch antenna array is disclosed. The device comprises a feed section (1) having at least two input transmission lines, a feed/wave-guide interface (5) providing an aperture for transferring a radio frequency electromagnetic wave between the feed section (1) and a wave-guide mode in a wave-guide section (3) having ridges. The wave-guide section transfers energy between the feed/wave-guide interface and a tapered notch section (7), thereby gradually adjusting a created electromagnetic field towards free space conditions.