Compact UWB Monopole Antenna with Tunable Dual Band Notched Characteristics for WiMAX and WLAN Applications

Abstract

The present work shows a planar compact ultra-wideband (UWB) monopole antenna with controllable dual
band-notch frequencies at 3.3 GHz for WiMAX and 5 GHz for WLAN. In the proposed antenna, the lower notch
band (at a frequency of 3.3 GHz) is made by cutting a thin horizontal strip on top of the radiating patch. The upper
notch band (at a frequency of 5 GHz) is made by putting two narrow parasitic strips in the shape of an “I” on
either side of the radiating patch. The incorporation of three varactor diodes between the radiating patch and three metallic strips provides the flexibility of adjusting the notch frequencies. The notch band tunability between 3.15 GHz and 3.69 GHz and between 4.93 GHz and 5.59 GHz, respectively, is achieved by changing the bias voltage
of the varactor diode between 0 V and 30 V. The gain and efficiency characteristics of the designed antenna also
exhibit band rejection at the respective notch frequencies. The design principle is validated by fabricating and
measuring a prototype of the proposed dual-band, notched UWB antenna. For three different bias voltages of the
varactor, the simulated and experimental findings are in reasonable agreement. The proposed works demonstrate
better-notch characteristics as compared with other reported works over the UWB range