novel Ultra-wideband Willis-Sinha Tapered Slot antenna for landmine detection using Ground Penetrating Radar (GPR) system with enhanced gain and directivity is presented. The structure is constructed on a 235x270 mm2 FR4 dielectric substrate. The antenna is fed by a novel tapered coplanar waveguide (CPW) to coplanar stripline (CPS) transition feed. The antenna's impedance bandwidth is extended by adding an antenna arm constructing parabola shape with the antenna element. The antenna has a corrugated structure along the antenna outer edges to improve radiation efficiency and get higher directivity. Also, a mushroom-like circular EBG structure is used in the lower side of the antenna arm to reduce interference and enhance front-to-back ratio (F/B ratio). A partial substrate removal, like circular cylinders inside the substrate, is aligned with the antenna tapered profile to obtain better radiation efficiency and enhance antenna gain. The operational bandwidth of this antenna extends from 0.18 to 6.2 GHz. The minimum return loss reaches 60 dB. The average directivity reaches 12.2 dBi while the gain and radiation efficiency are 11.8 dBi and 92%, respectively with gain enhancement of 195% due to using corrugated structure and air cavities. The front-to-back ratio (F/B ratio) is 23 dB. Also, a size reduction of 48% is achieved due to using extended arm. The antenna performance was simulated and measured. Good agreement was found between numerical and experimental results. The proposed antenna is suitable for various ultra-wideband applications especially in landmine detection. The design of the proposed antenna is given in very simple five design steps.
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