In-line filter having mutually compensating inductive and capacitive coupling

An in-line resonator filter comprising a linear array of three or more conductors, the linear array comprising:

• a first conductor and a second conductor adjacent the first conductor that together comprise a first pair of conductors having inductive main coupling and oppositely signed capacitive main coupling;
• a third conductor adjacent the second conductor opposite the first conductor, the first and third conductors together comprising a second pair of non-adjacent conductors having inductive cross-coupling;
• and
• an adjustable tuning element extending between the second conductor and the third conductor,
• wherein there is no direct ohmic connection that provides the corresponding inductive cross-coupling between the first and third conductors, and
• at least a portion of the oppositely signed capacitive main coupling compensates for at least a portion of the inductive main coupling between the first pair of adjacent conductors.

An in-line resonator filter comprising a linear array of three or more conductors, the linear array comprising:

• a first pair of adjacent conductors having inductive main coupling and oppositely signed capacitive main coupling;
• a second pair of non-adjacent conductors having inductive cross-coupling;
• wherein:
• the first and second pairs have one conductor in common;
• between the second pair of non-adjacent conductors, there is no direct ohmic connection that provides the corresponding inductive cross-coupling;
• and
• at least a portion of the oppositely signed capacitive main coupling compensates for at least a portion of the inductive main coupling between the first pair of adjacent conductors,
• wherein each conductor comprises:
• a base that is shorted to a bottom ground plane of the in-line resonator filter;
• and
• a low-impedance shaped head that has a cup-shape or a fork shape that does not contact a top ground plane of the in-line resonator filter.