Low-loss tunable radio frequency filter

A method of tuning a radio frequency (RF) filter, comprising a signal transmission path having an input and an output, a plurality of resonant elements disposed along the signal transmission path between the input and the output, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and at least one sub-band between the transmission zeroes, wherein the non-resonant elements comprise at least one variable non-resonant element for selectively introducing at least one reflection zero within the stop band to create a pass band in one of the at least one sub-bands, the method comprising:

• measuring a response of the filter to generate a set of measured data;
• analyzing the set of measured data to extract one or more filter design parameters to optimize;
• optimizing the one or more filter design parameters to achieve a desired filter response;
• generating a tuning recipe based on the one or more optimized filter design parameters;
• and
• tuning the filter by varying one of the at least one non-resonant element to selectively move the respective reflection zero along the stop band to move the pass band within a selected one of the sub-bands.