A compact self-grounded ultra-wideband bow-tie antenna is presented that operates in a frequency range from 279 MHz (19F at 7.0 T) up to 500 MHz (1H at 11.7 T). The antenna is smaller and lighter than previous designs making it an excellent candidate for high density multi-channel transmit/receive arrays. It can be driven directly at 50Ω eliminating the need for a tuning/matching circuit and associated component losses and costs. The ultra-wideband antenna was tested successfully in-vivo at 7.0 T for 19F and 1H imaging. Its design supports high average power applications such as targeted RF heating or thermal MR.