Abstract: An iris is located in a common wall separating two microwave enclosures such as waveguides and cavities for coupling electromagnetic power between the two enclosures. The iris is formed of an aperture elongated in one direction to define a longitudinal axis of the aperture with opposed first and second sides parallel to the axis. Portions of the common wall at peripheral regions of the aperture are extended from the first and second sides towards the iris and perpendicularly thereto to form teeth, there being an array of teeth extending from the first side and an array of teeth extending from the second side. The teeth are readily polarized as magnetic dipoles by surface currents induced in the wall by electromagnetic waves for increased coefficient of coupling of electromagnetic field components through the iris.

Abstract: A microwave band pass filter for filtering electromagnetic signals has a set of cavities arranged serially, with a block of dielectric material filling each cavity to define regions of each cavity which are loaded with dielectric material and regions which are free of the dielectric material. Each cavity may be viewed as a resonator for a fundamental mode of progagation of an electromagnetic wave while each block can be viewed as a resonator for higher-order modes of propagation of electromagnetic power. The cavities are separated by walls having slots aligned with the free regions of the cavities for coupling power from the fundamental mode while minimizing interaction with power of the higher-order modes. The filter enables the construction of an enlarged passband while inhibiting the presence of the spurious higher-order modes in a stop band bordering the passband.

Abstract: A filter system is composed of two identical filters coupled between an input waveguide and an output waveguide to provide a 4-port directional filter characteristic operable with quasi-elliptic linear modes of electromagnetic propagation within each of the filters. Each of the filters may be constructed of a plurality of cavities arranged serially, one behind the other, with one of the cavities in each of the filters being employed for coupling electromagnetic power between the two waveguides. The coupling is accomplished by use of a transverse slot and a longitudinal slot in each of the waveguides, the slots extending through sidewalls of the waveguides into walls of the cavity in each of the filters for symmetric and antisymmetric coupling, respectively, of longitudinal and transverse components of a transverse electric wave in each of the waveguides.