Abstract: A filtering system for separating a composite signal containing two signals in different frequency bands: a high frequency signal and a low frequency signal. The composite signal to be separated is input into an inductive element in a high frequency filter section. The high frequency signal is immediately coupled by mutual induction with a resonant element of the high frequency filter section, the resonant element being designed so that the low frequency signal is not coupled because of the low value of its frequency. The low frequency signal is transmitted to low pass filter section which rejects any signal remaining in the high frequency band.

Abstract: A method for increasing the directivity and adaptation of directive microwave couplers formed of two spaced apart lines, in which the length of each line is reduced to a value of less than one quarter of the operating wavelength. Capacitance is added to the coupler to counter the reduction of capacitance resulting from the shortened lines. The capacitance is added by: (1) increasing the surface area of the shortened lines by adding lateral pads; and (2) providing a dielectric bridge across the pads.

Abstract: Numerous high frequency signals are combined in a system of cavity band-pass filters. Each filter has a bottle shape so that adjacent filters may be fitted together into a compact system. Bridges connect the adjacent filters.

Abstract: Two microwave signals of identical frequency, possibly differing in amplitude and/or phase from each other, are combined by feeding them to respective inputs of a directional coupler with outputs each carrying an unshifted component of one and a quadrature-shifted component of the other input signal. The composite output signals of the coupler are fed to a hybrid junction which combines them cophasally into a sum signal and with relative phase inversion into a difference signal. The sum signal, besides energizing a load, is applied directly to a reference input of a first coherent detector and through a 90.degree. phase shifter to a reference input of a second coherent detector each receiving the difference signal on a monitoring input. The first detector controls a phase shifter upstream of one of the coupler inputs to correct for phase deviations while the second detector controls a phase shifter downstream of one of the coupler outputs to correct for changes in relative amplitude.

Abstract: A rectangular waveguide energized in the TE.sub.10 mode is externally provided on at least one of its major surfaces with one or more pairs of ferrite cores rising from that surface on opposite sides of its electric plane, an end face of each ferrite core being aligned with an aperture in the guide surface whereby two counterrotating magnetic fields in the interior of the guide induce corresponding fields in the two cores. The induced magnetic fields travel outward in the cores and are reflected at their remote ends for return to the guide with a phase shift controlled by a unipolar biasing current traversing a pair of coils which are respectively wound about these cores to generate two mutually opposite magnetic fields therein. The cores and their coils may be spacedly surrounded by an enclosure for the forced circulation of a cooling fluid therearound.