Frequency and bandwidth reconfigurable monopole antenna for cognitive radios

A miniature frequency bandwidth reconfigurable antenna is presented. Four slots and a ring slot resonator are integrated to the ground plane of an UWB antenna in order to achieve frequency reconfiguration, maintaining the original size unchanged. The proposed antenna is capable of adjusting both the frequency and the bandwidth by using switches to control the electrical length of the slots, offering thus pre-filtering functionality. Antenna performance obtained from simulation and measurement results shows a fair agreement, which validates the proposed design approach. The antenna is potentially suitable for wireless communication and cognitive radio.

I. Introduction

With the development of wireless communication systems, more and more applications are using the free space to send and receive data and spectrum saturation problem has become a concern. Cognitive radios are presented as the solution to this problem by allowing them to operate in part of the spectrum. Frequency reconfigurable antennas for cognitive radios have been widely investigated [1]–[4]. However most of these works concentrate on band switching in the narrowband mode. In this paper, a new design of reconfigurable monopole antenna that allows controlling both the frequency and the bandwidth is presented. By incorporating four slots and a ring slot to the ground plane, the antenna can be switched between four different frequency bandwidths within the ultra-wideband range. To achieve switched band properties, the proposed approach consists in varying the electrical length of the slot resonators by means of switches. To present the work, the used approach to propose this new antenna is described. Then both simulated and measured are given and sicussed.