This paper demonstrates a matched bandstop resonator with a tunable K inverter. Two separated λ/4 resonators are coupled through a tunable impedance inverter which consists of a varactor loaded microstrip T-shunt stub. In contrast to conventional K-inverter realizations, which possess narrowband properties, this paper demonstrates a physical realization of a novel tunable K-inverter using a varactor diode. Theoretical analysis together with the experimental results is presented in this paper.

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... e optimum coupling value can be easily achieved by independently tuning the varactor where an enhanced notch response with 64dB attenuation is measured and shown in this paper. Index Terms -Notch filter, immitance inverter.