Compact CoPlanar Waveguide-fed Ultra Wide Band and Band Switchable Slot Antenna for Cognitive Radio Front-end System

Abstract

A compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) slot antenna with four narrowband switchable states is presented in this paper. Cognitive Radio (CR) portable devices demand a compact antenna. In planar monopole antennas where a large space around the patch is getting wasted that can effectively be used in UWB slot antennas. The proposed antenna consists of a half-elliptical slot radiator fed through a half-elliptical shaped tuning stub to operate in the UWB mode for CR sensing. However narrowband antenna is required to operate in CR communication purpose. To operate in the narrowband mode the UWB slot antenna is fed through a defected ground structure (DGS) integrated CPW line. Frequency re-configurability is achieved by changing the DGS slot length using eight PIN diode switches. The proposed compact antenna can cover UWB frequency range from 3.14 GHz to 12 GHz. It has omnidirectional radiation pattern and also has high realized gain which is especially suited for CR front-end applications.