A tunable dual-mode bandstop filter based on liquid crystal technology

In this paper, a novel tunable microwave bandstop filter (BSF) based on LC technology is proposed. A meander loop resonator with two open-circuited stubs located into the input and output ports are used in the design. Due to two additional open-circuited stubs, the proposed filter has better rejection in the stopband performance without increasing the circuit size. For ease of supplying ac voltages, the proposed filter is achieved by inverted-microstrip structures, in which the input and output ports are connected by metal vias. By taking advantage of the property of LC, central frequency tunability is introduced by applying low ac voltages. What´s more, the proposed LC BSF is low power consumption, small cost and relatively small sizes.