A passband filter where the central frequency can be one of seven selectable frequencies is presented. Its operation region ranges from 325 to 455 MHz, and each bandwidth is about 20 MHz. The filter is based on a highly miniaturized ring resonator with a size reduction from about 77% to 83% compared to a conventional closed ring. The reconfiguration of its resonant frequency is implemented by shifting a short location, thus changing its effective inductance. This is opposed to the conventional capacitance change of other reconfigurable filters. Simulated and experimental results are in good agreement. Reflections are below -10 dB at central bandpass frequencies for all selectable bands.
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