Planar general response dual-mode cavity filter

Abstract

An electromagnetic cavity filter is formed by at least two cavities having electrically conductive walls. Each cavity is the equivalent of two filter poles because two orthogonal modes of electromagnetic radiation can resonate within each cavity. Characterizing vector tuning elements are coupled to each of the cavities that are each aligned along respective axes. The tuning elements are used to provoke derivative orthogonal modes and determine the degree of coupling between orthogonal modes. One or more intercavity couplers interconnect the cavities and are rotated at arbitrary angles that are different from the axes of the characterizing vector tuning elements. Electrically adjacent and nonadjacent modes of proximate cavities can be coupled, permitting elliptic filter functions. Electrically nonadjacent modes are coupled by means of an iris interconnecting the two cavities. Electrically adjacent modes are coupled by means of an electrically conductive probe penetrating each of the cavities. A dielectric resonator may be disposed within each cavity to reduce the physical size of the cavity while preserving its electrical characteristics. Input and output coupling elements, coupled to selected cavities may be disposed at locations that are angularly rotated with respect to a corresponding characterizing vector tuning element by a selectable angle that varies between 0 and ±180 degrees.