Low-loss tunable radio frequency filter

A radio frequency (RF) filter, comprising:

• a signal transmission path having an input and an output;
• at least one resonant element disposed along the signal transmission path;
• and
• a plurality of non-resonant elements coupling the at least one resonant element between the input and the output to respectively form at least one transmission zero corresponding to at least one resonant frequency of the respective at least one resonant element and at least one reflection zero adjacent to one of the at least one transmission zero, wherein the plurality of non-resonant elements comprises at least one variable non-resonant element, each having a plurality of passive reactive elements coupled in parallel to each other to form a passive reactive circuit and at least one switch coupled to at least one of the passive reactive elements, wherein reactance of each of the least one variable element is configured to be varied by operating the at least one switch to selectively include or exclude the at least one passive reactive element from the passive reactive circuit to vary the reactance of the passive reactive circuit, thereby adjusting the position of the at least one reflection zero relative to the at least one transmission zero.