For phased array applications covering ultra wide bandwidth, it is necessary to restrict the size of the aperture to less than λ/2 at highest frequency of operation. For 6-18 GHz coverage, an aperture size of less than 9.76mm is required for scanning to ±450 without appearance of grating lobes and occurrence of element pattern nulls over the band. Meeting this requirement a printed tapered slot antenna has been designed with the above aperture size. Detailed parametric studies have been carried out over 6-18 GHz and dimensions have been opti-mized for return loss. The design has been carried out with HFSS software. A return loss of less than -7.5dB across 5.6 -20 GHz has been obtained for a single antenna. Also satisfactory radiation patterns have been obtained.