Abstract: An ultra-wideband resistor-loaded half-ellipse antenna with a shallow cavity for the vehicle-mounted Ground Penetrating Radar(GPR) is designed. The antenna with a pair of half-elliptical-shaped arms which is loaded by continuous resistive elements can effectively improve the input impedance characteristics and expand the bandwidth. The vehicle-mounted GPR for the exploration of lunar subsurface is taken as the background. The performance of the proposed antenna with different height above ground surface is studied, and the influence of the vehicle to the antenna is analyzed. An antenna prototype was manufactured and mounted on a vehicle and field tests were done. The simulated and measured results show that the designed antenna has a low voltage standing wave ratio, good radiation characteristics and small late-time ringing, which can satisfy the requirements of the GPR system.