broadside direction on the radiation pattern, especially at the higher frequency band. However, the overall antenna pattern shows the unidirectional radiation to the desired target direction, which is useful for the high-directive radar imaging applications. It is observed from the simulation results that the gain of the bowtie antenna with a reflector increases from 6.5 to 8.5 dBi, almost double the case without a reflector, which gives more high directional gain to the target direction. CONCLUSIONA novel unidirectional horn-shaped tapered bowtie slot antenna with a pyramidal reflector has been designed and fabricated for ultra high-resolution radar imaging applications. The implemented antenna performance shows very low return loss less than Ϫ10 dB over 3.0 -11.7 GHz and a quasi-unidirectional radiation that shows a high front-to-back ratio over the whole UWB frequency band. This result shows enhanced new performance compared with the previously available antenna design, which will be useful for ultra high-resolution UWB radarimaging applications.