Design of miniaturized reconfigurable slot antenna using varactor diodes for cognitive radio systems

Abstract

In this paper, a new compact tunable microstrip-line fed slot antenna is proposed for interweave cognitive radio (CR) front end systems. The proposed antenna utilized four varactor diodes to control the antenna resonant frequency. The resonant frequency of the antenna can be electronically tuned by changing the effective electrical length of the resonant slot, which is accomplished by employing the varactor diodes inside the slot. Moreover, the simple biasing of the varactor diodes has a small effect on the antenna performance. Simulation results show that the proposed antenna is capable of frequency switching over a tuning range of 0.93 GHz from 1.83 to 2.76 GHz with 40.5 % frequency tuning range. The proposed antenna has a miniaturized size of 25 × 30 × 0.762 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .