UWB Positioning System with Orientation-Independent Characteristic by Using Omnidirectional Circularly Polarized Antenna

This work presents an ultra-wideband (UWB) positioning system with a novel circularly polarized antenna. The design, implementation, and measurement of the proposed circularly polarized antenna with orientation-independent characteristic are demonstrated. Good impedance matching and omnidirectional radiating properties of the proposed circularly polarized antenna are verified in the UWB frequency band, which is the channel 1 of UWB module DWM1000. The measured 3-dB axial ratio and the omnidirectional radiation pattern on the azimuth plane of the proposed circularly polarized antenna operated at 3.5 GHz are achieved. Results demonstrate that the variation of group delay of the proposed circularly polarized antenna is lower than the linearly polarized antenna so that the proposed antenna is suitable for UWB positioning system. The UWB positioning system measurement reveals that the positioning accuracy of this work is high even if the location or polarization of object changes.