Wideband reconfigurable bandstop filter for future wireless communication

This paper presents a novel reconfigurable bandstop filter for future wideband wireless communication systems. The filter consists of a parallel coupled-line and two varactor diodes etched onto standard FR4 board. The structure of this filter is simple and could easily be integrated with other microwave circuitry. Measurement results show that the stopband of the filter can be tuned from 0.47GHz to 1.67GHz. This is achieved by varying the capacitance of a pair of varactor diodes. Although still present, the first harmonic of the fundamental stopband is significant attenuated. The stopband tuning range is restricted by the capacitance variation which can be achieved using the varactor diode. The potential tuning range of this filter is more than 2 octaves, and has been developed for integration into a wide band circular array with reconfigurable pattern and frequency notch.