Miniaturized Switchable Bandpass to Matched Bandstop Filter Using Stepped-Impedance Resonator

A new miniaturized switchable bandpass to matched bandstop filter using stepped-impedance resonator is proposed in this paper. Generally, the structure is composed of stepped-impedance resonator and λ/\pmb4 wavelength line to achieve the matched bandstop filter at a frequency of 2.4 GHz. P-i-n diodes are used to connect and disconnect between stepped-impedance resonator and λ/4 wavelength line. In the OFF state, the switchable filter produced a bandpass response, while in the ON state, the switchable filter produced matched bandstop response. A good agreement between simulation results and measurements has been achieved. Experimental results show that this type of filter can be switched either to perform the matched bandstop or bandpass response.