A novel ellipse cavity-backed and slot-tuned bow-tie antenna was designed to facilitate the application of ultra-wide band (UWB) ground penetrating radar (GPR) in low frequency. Lumped resistor loading was applied at the end of antenna arms to broaden the impedance bandwidth. Taper tuned method was also used to optimize the current distribution. Antenna characteristic was analyzed by simulation. Finally, pairs of antenna were manufactured and measured. The measured results showed that the proposed antenna had an impedance bandwidth from 12 MHz to 143 MHz with VSWR smaller than 2. The antenna achieves a compact size with 1.52∗0.58∗0.41 m3 by ellipse-shape cavity. Furthermore, road detection experiment demonstrates that the antenna can be well suitable for relatively deep target detection.