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Imaging radar has become a keen research topic in recent years. UWB technology provides many advantages to imaging radar such as fine resolution and high power efficiency. The performance of a UWB imaging radar can be further improved by applying polarimetric diversity. The polarimetric signature of objects can be used to enhance the quality of target recognition. Like any other wireless systems, antennas are key factors of radar systems. The focus of this thesis is to develop a dual polarized antenna for UWB imaging radar. An antenna element was designed for the Ku-band and an impedance bandwidth from 8 GHz to 24 GHz was achieved. An orthogonal coax-to-coplanar transition has been developed during this project and this transition is used to feed the antenna element. The antenna elements are successfully applied in two different array configurations. It is demonstrated that these sub-arrays have over 100% fractional bandwidth, good impedance matching, linear phase (almost constant group delay) and uni-directional pattern. These aspects collectively account for the novelty in design. In future, these sub-arrays will be implemented inside a complete array structure of UWB imaging radar.