Abstract: An ultra-wideband（UWB） single-notch omnidirectional antenna with 5.8 GHz WLAN depth suppression characteristics is designed for the UWB indoor positioning system. An “inverted arrow” shaped patch is used as radiating unit. A rectangular open-circuit groove and right-angled triangle truncation are etched on the rectangular ground to obtain a wider impedance bandwidth. A half-wavelength C-shaped groove is etched on the radiation patch, and A half-wavelength RSCSRR（rectangular single complementary split ring resonator） groove pair are etched on the ground to achieve deep suppression of 5.8 GHz WLAN signals. The simulation results show that the impedance bandwidth of the antenna is 3.10 GHz～10.60 GHz, and the voltage standing wave ratio（VSWR） at the 5.8 GHz notch reaches 7.59. The measured S₁₁ and VSWR are in good agreement with simulations, which verifies the effectiveness of the notch; the measured patterns at 4 GHz, 6.5 GHz and 9 GHz show good radiation characteristics and omnidirectionality within the entire UWB band, satisfying antenna requirements of indoor positioning system.