Design of a UWB antenna with stabilized radiation pattern

The UWB circular disc monopole (CDM) antenna has been previously used for positioning applications. But at higher frequencies, its pattern does not remain omnidirectional in azimuth and it tends to shift upward. We propose new structures for both monopole radiator and ground plane to yield an antenna with a stabilized radiation pattern. Comparing the main lobe characteristics of the proposed and CDM antenna shows that the proposed one radiates in the horizon plane with enhanced electric field at higher frequencies. All root-mean-square differences for S11 and S21 for MOM simulation and measured results are around 3 dB between 1 to 10 GHz, which is a reasonable value.