Abstract: An input signal is supplied to a first port of a non-reversible circuit and those frequency components of the input signal applied to a second port of the non-reversible circuit which differ from the resonance frequency of a resonance element connected to the second port are absorbed by a resistive terminating element connected to the second port. On the other hand, a frequency component of the input signal which coincides with the resonance frequency is derived at the third port of the non-reversible circuit. By changing the resonance frequency of the resonance element, the frequency component of the input signal which are provided to the third port can be altered.

Abstract: A band-pass filter comprising n principal linear resonators open at both their extremities, has integrated therewith a band suppressor function by means of p auxiliary linear resonators (p being an integer comprised between 0 and n+1), tuned to a frequency which is to be rejected and respectively connected to p resonators of the n principal resonators at a point situated close to the middle of the principal resonator in question.

Abstract: The invention is directed to a interdigital filter comprising a plurality of conductive strips positioned in a row and electromagetically coupled to one another. A conductive transmission line is positioned with respect to the row of conductive strips such that the two ends of the transmission line are capacitively coupled to the ungrounded ends of two nonadjacent conductive strips. This arrangement gives the frequency response of the filter a transmission zero. The frequency of the transmission zero can be adjusted by trimming the ends of the conductive transmission line so as to effect the capacitive coupling between the non-adjacent strips.

Abstract: A thin film structure is provided with the capability of low-power laser tuning and trimming. Trim windows in a plated ground plane are incorporated to allow automated tuning procedures using relatively low-power lasers. The trim windows are conductive, but the heavier layer of plated copper is omitted from those areas, leaving only the titanium/evaporated copper/ gold layers. The method can also provide for areas of bare substrate if desired.

Abstract: The Frequency response of a Microstrip Interdigital Filter (MIDF) is improved by providing a specially dimensioned top cover separated from the MIDF ground plane along one or both of its edges by a dielectric layer comprised of thin dielectric sheets. While the upper frequency skirt is mainly determined by the MIDF itself, the bandwidth may be reduced and the slope of the lower frequency skirt may be enhanced by providing the cover in accordance with the invention. The thickness of the dielectric layer can be chosen to further improve the slope of the low frequency skirt by effectively moving the filter zero closer to the desired low frequency cut-off of the filter. The particular choice of the dielectric thickness will not substantially affect the filter bandwidth.

Abstract: An adjustable passband filter comprises at least one reentrant section in shunt with a transmission line, which section can be electronically switched between different conditions. The reentrant section, when in at least one condition acts, to reduce the band of frequencies passed by the transmission line by increasing the effective capacitance of the filter and when in another condition, operates as an open circuit, whereby the filter exhibits a broader passband.

Abstract: A comb-line bandpass filter comprising an enclosure or outer conductor and a plurality of inner conductors arranged parallel in the outer conductor. Adjacent to one end of each inner conductor a body of dielectric material is attached to provide a larger diameter, lumped capacitance section while providing a lumped inductance section in the remainder of the inner conductor. A conductive layer, conductively coupled to the outer conductor, encircles the dielectric body to act as a shield between adjacent inner conductors so that the coupling between them is concentrated in the inductive section. Overall size of the comb-line filter is reduced by reduction both in axial length of the inner conductors and the spacing between them.

Abstract: Compact, simple, ferromagnetic-filter coupling structures which provide a very high, effective-quality factor Q in the VHF, UHF, and microwave frequency ranges achieved by means of offsetting the ferromagnetic element from the plane of the coupling loops and by phase shifting the current in one of the coupling loops to produce an orthogonal field in the vicinity of the ferromagnetic element.

Abstract: The invention is a magnetically tunable bandpass filter for use in the miwave regions, particularly for frequencies between 0.1-4 GHz. A magnetically tunable bandpass filter is a filter which will pass only certain frequencies from one conductor to a separate conductor depending upon the frequency band and the magnetic field applied across the filter. The tuning of the center frequency can be achieved at relatively fast electronic switch times. The center frequency is the frequency at which the most coupling exist due to the applied magnetic field. Two striplines are placed at 90.degree. relative to one another with one end of one stripline overlapping one end of the other with the overlapped ends connected to ground. A disc of ferromagnetic material is placed between the two striplines.

Abstract: A building block resonator is fabricated using a single chemically milled copper pattern and two pieces of garnet material to form a quarter-wave transmission line which is shorted at one end. Tuning is achieved with an electromagnet by varying the static magnetic field perpendicular to the resonator which causes the permeability of the garnet material to change. Resonators formed in this manner can be cascaded in any number to form a multi-pole filter. Narrow band UHF filters (0.5 percent 3 dB bandwidth at 225-400 megahertz) can be built in a very compact form. The magnetic tuning field intensities used are above the saturation point of the garnet, and high power level operation devoid of non-linear effects is possible.

Abstract: Transmission line filter adapted to respond to a predetermined frequency, having a resonator conducting layer with dielectric material on opposite sides thereof and a ground plane conducting layer on the outside surfaces of the dielectric material. The filter may be of the stripline or microstrip type having a resonator constructed so that it tends to operate at a frequency different from the desired frequency, and which is not accessible for trimming after the filter is constructed. The ground plane layer is accessible so that a portion thereof can be removed after the filter is constructed to change the electrical parameters of the line formed by the resonator and the ground plane layer to change the response frequency of the filter. Alternatively, conducting material can be added to an opening in the ground plane conducting layer to change the response frequency of the filter.