Low-profile BOR-SPR antenna with a stop band

The BOR-SPR is an antenna that has a wideband VSWR characteristic. To suppress interference signals, the BOR-SPR is modified to have a large VSWR in the frequency band that includes the interference signals (stop band). This is achieved by cutting slots in the shorted parasitic ring of the BOR-SPR. The analysis reveals that the slot length corresponds to approximately one-quarter guided wavelength at the center frequency of the stop band. It is also revealed that the slots do not affect the radiation pattern at frequencies outside the stop band.