UWB antenna with a WiMAX frequency notch caused by a novel stepped U shaped slot that suppresses the parasitic notches

UWB antennas with embedded stubs or slots can create a notch in the frequency range. The frequency notch and therefore the reduced radiation intensity is confined to frequencies used by other applications in order to achieve reduced interference. However the use of such resonant elements causes additional notches at the frequencies which equal to even or odd multiples of the design frequency. While the lowest odd multiple of the WLAN frequency (5.2-5.8 GHz) lays outside the UWB range (3.1-10.6 GHz) this is not the case for the WiMAX frequency. In this paper, a stepped slot is introduced in a UWB elliptical monopole that suppresses the unwanted higher order notch, and with the use of a linearly tapered feed line return loss better than -10dB is achieved throughout the UWB range with the exception of the WiMAX range.