Abstract: An oscillator (100) includes a resonator (218) having a mirco-strip (217). The micro-strip (217) couples an inductive component (221) to a capacitive portion (219). To tune the oscillator (100), a number of cuts are made on the pad (221) in order to restrict the signal flow. The width of these cuts determine the degree of restriction posed on the signal flow. This controllable restriction of the signal flow provides the circuit (100) with enhanced tunability.

Abstract: A helical resonator includes a helical coil with one end flared out and folded back over a portion of the cylindrical helix made by the coil to create a winding of opposite pitch superimposed over the cylindrical helix. As an alternative design, a resonator is formed of a helical coil of a first length connected to a helical of opposite pitch. This resonator inhibits a third harmonic resonance but re-resonates around the fourth harmonic. When this resonator is used in combination with a conventional helical resonator, the undesired re-resonances are suppressed.

Abstract: A helical resonator filter comprising two or more helical coils is provided with a conductive coupling element between the helical coils for modifying the filter bandwidth. A coupling element is a conductor and is positioned in the maximum of the electrical field at the open end of the helical coils or at the maximum of the magnetic field at the grounded end of the coils, or both thereby creating controlled change in capacitive (electrical) or inductive (magnetic) coupling, respectively. A block of suitable dielectric with grooves for receiving the coupling element and the ribs on the inside of a conductive cover can be used to center the coupling element and the whole filter assembly structure when the cover is put in place and clamps the block securely to the base of the filter. Additional coupling elements can be used in a similar manner as above when additional helical coils are used in a filter.

Abstract: A helical resonator filter includes several helical coils, each grounded at one end and free at the other and enclosed within a cavity. The coils are coupled to each other electromagnetically through apertures in the conductive walls separating the resonator cavities from each other. A dielectric member is inserted into the apertures to increase coupling between adjacent coils to increase the bandwidth of the filter.