Compact Planar UWB Antenna with Enhanced Bandwidth and Switchable Band-Notch Function for WLAN and DSRC

A novel planar switchable antenna with a band-notched and multi-resonance performance is proposed. In order to generate single band-notched characteristics, a parasitic element with two stubs is applied. Furthermore, to achieve a switchable function, only one PIN diode is used across a semicircular radiator patch and the parasitic element. When the PIN diode is forward biased, the semicircular patch transforms to a circular patch, and an additional resonance is excited at the notch frequency. Additionally, by attaching two L- and T-shaped stubs and cutting a rectangular slit on the radiating patch, new additional resonances are excited, and hence wider impedance bandwidth can be produced. The presented antenna has a compact size of 19.5 x 17 mm(2), equal to 0.2.0 x 0.17.0 (lambda(0) is the free-space wavelength at 3.1 GHz). The experimental and simulated results show that the antenna has a good radiation behavior within the ultra-wideband frequency range (3.08 to over 14 GHz) and reconfigurable frequency band-notched function in the range of wireless local area network and dedicated short-range communication signals (4.87-6.08 GHz). It is shown that there is virtually no change in the antenna's E-plane and H-plane radiation patterns for the various PIN diode switching conditions, especially at low frequencies.