Abstract: The present invention provides a dielectric waveguide filter comprising a plurality of dielectric waveguide resonators in the form of rectangular parallelepiped-shaped blocks aligned as a single main body having opposite ends defined by respective the end blocks located thereat, and a pair of input and output electrodes provided in the end blocks, respectively. Each of the end blocks is formed with a protruding portion including a dielectric substance extended from that therein. A conductive strip line extending from the bottom surface of corresponding one of the end blocks to the edge region of the bottom surface of corresponding one of the protruding portions. The bottom surfaces have a region where the dielectric substance in contact with the both sides of the conductive strip line is exposed to outside. The conductive strip lines are coupled with micro-strip lines or co-planer lines on a printed circuit board having a given length to obtain an adequate matching between input and output signals.

Abstract: A compact multiple VSWR element filter in which one or more of the VSWR filter elements is a waveguide bend or a waveguide media transition. Methods are also disclosed.

Abstract: An E-plane waveguide is provided comprising a housing having opposed walls defining a waveguide channel. The waveguide includes at least two elements spaced apart in a direction along the waveguide channel and disposed between and spaced from the opposed walls, and which define a resonant cavity therebetween with the waveguide channel. At least one of the walls has first and second protrusions which are spaced apart in a direction along the waveguide channel and protrude into the waveguide channel. The spacing between the protrusions is less than half a wavelength of the resonant frequency of the resonant cavity.

Abstract: Waveguide filters for filters operating at millimeter wavelengths which require high accuracy. The filter includes a plurality of discs held in the cylinder of a support. Each disc has a recess defining cavity size. The various parts forming the filter are simplified thereby making it possible to reduce production costs while providing good accuracy.

Abstract: A microwave waveguide filter includes a main-line cavity structure with a group of at least two rectangular main-line cavities arrayed along a main propagation path and including a first main-line cavity and a second main-line cavity. Each main-line cavity includes a sidewall, and each pair of adjacent main-line cavities has a common transverse wall transverse to the main propagation path and a main-line aperture in the common transverse wall. A rectangular first feedback cavity is in microwave communication with each of the first main-line cavity and the second main-line cavity through the respective sidewall of the first main-line cavity and the second main-line cavity. There is a first-cavity feedback aperture between the first feedback cavity and the first main-line cavity, and a second-cavity feedback aperture between the first feedback cavity and the second main-line cavity. There may be additional feedback cavities as well.

Abstract: A waveguide filter made a rectangular waveguide section 12 with cavities 14 forming resonators spaced along opposite walls of the waveguide is configured to reduce the harmonic passband amplitude noise due to higher order harmonics. The cavities 14 are modified from conventional cavities by having different lengths L1-L8 and widths A1-A8, as opposed to equal length and equal width values. Each cavity is designed to resonate at the desired principal frequency f1 according to the combination of the cavity width and length, but with cavities having different lengths and widths, synchronous resonances do not occur at higher order harmonic frequencies f2 and f3 normally occurring when the cavities all have equal widths and equal lengths.

Abstract: A microwave waveguide filter includes a main-line cavity structure with a group of at least two rectangular main-line cavities arrayed along a main propagation path and including a first main-line cavity and a second main-line cavity. Each main-line cavity includes a sidewall, and each pair of adjacent main-line cavities has a common transverse wall transverse to the main propagation path and a main-line aperture in the common transverse wall. A rectangular first feedback cavity is in microwave communication with each of the first main-line cavity and the second main-line cavity through the respective sidewall of the first main-line cavity and the second main-line cavity. There is a first-cavity feedback aperture between the first feedback cavity and the first main-line cavity, and a second-cavity feedback aperture between the first feedback cavity and the second main-line cavity. There may be additional feedback cavities as well.

Abstract: A radio frequency amplifier includes a waveguide filter positioned between a first and a second amplifier circuit, which reduces the distortion between the amplifier circuits. The waveguide includes a main body having a cavity.

Abstract: For fixing a dielectric insert in a waveguide, clamping bodies are provided which contact the dielectric insert on its outer periphery only tangentially. The dielectric insert is fixed in a wave propagation direction by a supporting element. In a further embodiment, the dielectric insert is rigidly mounted on the supporting element. As a result thermal stresses can be absorbed.

Abstract: Disclosed is a metal window filter assembly, of a millimeter wave band, using an NRD guide. The filter assembly comprises a filter housing including parallel conductive plates and a filter for filtering a certain frequency band of an electromagnetic wave traveling therethrough. The filter includes a plurality of polygonal metal windows and a single body type dielectric line made from a non-radiative dielectric. A plurality of polygonal inserting grooves spaced by the predetermined distance are formed respectively on both surfaces of the dielectric line making contact with the parallel conductive plates. The metal windows are inserted in the inserting grooves one to one to form multi-staged dielectric resonators cascaded as a single body. The filter has a filtering function selectively passing the certain frequency band determined by an impedance coupling relationship that the multi-staged dielectric resonators have with respect to the electromagnetic wave.

Abstract: An E-plane filter comprises a housing having a waveguide filter channel and a septum defining a plurality of couplers spaced apart along the length of the filter channel, thereby forming a resonator cavity between each adjacent coupler. The portion of the filter channel which accommodates the couplers and each resonator cavity is curved or otherwise changes direction in a plane transverse to the channel walls.

Abstract: The invention relates to a device for rotating through a predefined angle the polarization of a polarized electromagnetic wave propagating in a first waveguide. According to the invention, the device comprises a second waveguide having a lateral port, the polarized electromagnetic wave propagates between a port of the first waveguide and the lateral port of the second waveguide via a coupling orifice that is smaller than the cross-section of the first waveguide and whose geometry is adapted to provide electromagnetic coupling between the first waveguide and the second waveguide, and the other port of the second waveguide is on a face perpendicular to the lateral port.

Abstract: The present invention relates to a device at filters for filtering unwanted signals from radio transmitters and/or for use during combination of radio transmitters. Said filter (1) has at least one cavity (2 and/or 3) for filtering radio signals. At least one compensating means (13 and/or 16) is provided to compensate for deviations in frequency depending on expansion or contraction of the cavity (2 and/or 3) due to expansion or contraction of the filter (1) when said filter is heated or cooled during operation. The filter (1) has at least one cavity (2 and/or 3) which is designed for simultaneous filtering of radio signals of at least three different modes (A, B and C and/or D, E and F) and the same frequency. The compensating means (13 and/or 16) is provided in said cavity (2 and/or 3) for compensating deviations in frequency by simultaneously affecting the radio signals of the at least three different modes (A, B and C and/or D, E and F).

Abstract: A directional coupler includes two non-radiative dielectric lines, each formed by a dielectric strip between flat conductive surfaces placed substantially parallel to each other, such that the two non-radiative dielectric lines are close to each other. The main transmission mode of electromagnetic waves at the frequency used is an LSE mode, the electromagnetic waves being propagated in the non-radiative dielectric lines. Therefore, the insertion loss due to mode switching in the coupling portion of the primary line and the secondary line which form the directional coupler can be reduced, and leakage of the electromagnetic waves from the gap between the primary line and the secondary line of the directional coupler when they are separated from each other can be suppressed.

Abstract: The invention provides a dual-mode microwave filter, comprising a rectangular resonator of length l, height b, and width a operating in two distinct modes (m, 0, n) and (p, 0, q) from a single family of modes and presenting the same direction as the E field, and wherein coupling and mode excitation discontinuities are inductive and in the same direction.

Abstract: A ridge waveguide filter which is formed of metallized blind vias in a plurality of contiguous layers of a dielectric medium including low temperature cofired ceramic (LTCC), high temperature cofired ceramic (HTCC) or organic printed wiring boards (PWB) in the fabrication of the waveguide sidewalls and solid ground planes to provide top and bottom walls as well as in the formation of a plurality of ridge waveguide sections in an embedded ridge waveguide structure. Patterns of conductive metal are selectively printed on the outer surface of certain dielectric layers to electrically short all the vias in the ridge waveguide sections and the adjacent wall vias so that the elements behave as though they comprise a solid metal structure.

Abstract: A bandpass filter makes use of at least one waveguide cavity that is thermally compensated to minimize drift of a resonant frequency of the cavity with thermal expansion of cavity components. The compensation relies on deformation of the shape of at least one cavity surface in response to thermally induced dimensional changes of the cavity. A control rod is used to limit the movement of a point on the deformed surface, while the rest of the surface moves with the thermal expansion. The control rod is made of a material having a coefficient of thermal expansion that is significantly different than that of other filter components. The rod may also be arranged to span more thermally expandable material than defines the filter such that, as the filter expands, the point of deflection is moved toward the interior of the filter beyond its original position.

Abstract: The present invention provides a dielectric waveguide filter comprising a plurality of dielectric waveguide resonators in the form of rectangular parallelepiped-shaped blocks aligned as a single main body having opposite ends defined by respective the end blocks located thereat, and a pair of input and output electrodes provided in the end blocks, respectively. Each of the end blocks is formed with a protruding portion including a dielectric substance extended from that therein. A conductive strip line extending from the bottom surface of corresponding one of the end blocks to the edge region of the bottom surface of corresponding one of the protruding portions. The bottom surfaces have a region where the dielectric substance in contact with the both sides of the conductive strip line is exposed to outside. The conductive strip lines are coupled with micro-strip lines or co-planer lines on a printed circuit board having a given length to obtain an adequate matching between input and output signals.

Abstract: In a dual-mode bandpass filter, a metal film is partially formed on one surface of a dielectric substrate or at a certain vertical level within the dielectric substrate, first and second input/output coupling circuits are coupled to the metal film, at least one capacitor is loaded to the metal film so that when an input signal is applied from either input/output coupling circuit, two resonant modes generated in the metal film are coupled. The capacitor preferably includes via-hole electrodes opposing the metal film.

Abstract: Disclosed is a metal window filter assembly, of a millimeter wave band, using an NRD guide. The filter assembly comprises a filter housing including parallel conductive plates and a filter for filtering a certain frequency band of an electromagnetic wave traveling therethrough. The filter includes a plurality of polygonal metal windows and a single body type dielectric line made from a non-radiative dielectric. A plurality of polygonal inserting grooves spaced by the predetermined distance are formed respectively on both surfaces of the dielectric line making contact with the parallel conductive plates. The metal windows are inserted in the inserting grooves one to one to form multi-staged dielectric resonators cascaded as a single body. The filter has a filtering function selectively passing the certain frequency band determined by an impedance coupling relationship that the multi-staged dielectric resonators have with respect to the electromagnetic wave.

Abstract: The waveguide group branching filter according to the present invention is formed by boring out of two metal blocks constituent circuits including a circular-to-square waveguide multistage transformer 1, the branch waveguide polarizer/branching filter 4, a rectangular waveguide multistage transform 9, the rectangular waveguide H-plane T-branch circuit 10, and waveguide band-pass filters 8, 14 and 18; radio waves V1 and H1, which have their polarization planes vertical and horizontal, respectively, to the branching plane of the branch waveguide polarizer/branching filter 4 in a certain frequency band f1, and a radio wave V2 of the same polarization plane as that of the radio wave V1 in a frequency band f2 higher than the frequency band f1 are incident to an input port P1, and the radio wave V1 is emitted from an output port P2, the radio wave H1 from an output port P3 and the radio wave V2 from an output port P4.

Abstract: An improved stepped-impedance low pass filter includes a stepped-impedance low pass filter having at least one electrically conductive transmission line, such as a parallel plate, coaxial, or two-wire transmission line, having at least one inductive element and at least one capacitive element. The capacitive elements and the inductive elements are disposed in an alternating manner along a length of the transmission line. The resonance suppressed stepped-impedance low pass filter also includes at least one electrically conductive suppression element disposed along the inductive elements of the stepped-impedance low pass filter, such as centered along the inductive elements between pairs of capacitive elements. The suppression elements suppress a spurious response at at least one resonant frequency.

Abstract: A cavity filter (15) includes a dielectric block (25) disposed adjacent to a conductive layer (23) for producing a resonant frequency of the cavity filter. An electromagnetic signal (VA) propagates within the dielectric block for a predetermined distance to a surface (58) of the conductive layer, where the predetermined distance is one-fourth of a wavelength of the electromagnetic signal at the resonant frequency.

Abstract: Disclosed is a metal post filter assembly, of a millimeter wave band, using an NRD guide. A filter to which an electromagnetic wave travels is disposed in a filter housing which includes parallel conductive plates facing each other. The filter forms a plurality of inserting holes, by segmenting them into multi-stages, along the length direction of side surface of a dielectric line and parallel to the parallel conductive plates. The filter has a structure that multi-staged dielectric resonators are formed in a single body by inserting metal posts which provide discontinuous surfaces which cause a reflection with respect to the electromagnetic wave in each of the inserting holes. Each impedance of the multi-staged dielectric resonators has an impedance coupling relationship that the impedance becomes gradually and symmetrically smaller to both end stages.

Abstract: A precision non-symmetrical L-shape waveguide end-launching probe for launching microwave signals in both vertical and horizontal polarizations is disclosed. The L-shape waveguide probe is in a form of thin plate, has a first arm and a second arm, and is precisely fabricated and attached to one end of the central metal pin of a feedthrough. The feedthrough is installed to an aperture formed in a major wall of the universal conductive housing to achieve hermetic sealing. The L-shape waveguide probe is aligned by means of a specially designed alignment tool so that long axis of the second arm is always perpendicular to the broad walls of the output waveguide, which is mounted to the universal housing with the broad walls of the output waveguide either horizontally or vertically. Hence, in this invention, an end-launching arrangement using the L-shape probes that could yield a flexible waveguide interface either in horizontal polarization or vertical polarization is provided.

Abstract: Disclosed is a metal post filter assembly, of a millimeter wave band, using an NRD guide. A filter to which an electromagnetic wave travels is disposed in a filter housing which includes parallel conductive plates facing each other. The filter forms a plurality of inserting holes, by segmenting them into multi-stages, along the length direction of side surface of a dielectric line and parallel to the parallel conductive plates. The filter has a structure that multi-staged dielectric resonators are formed in a single body by inserting metal posts which provide discontinuous surfaces which cause a reflection with respect to the electromagnetic wave in each of the inserting holes. Each impedance of the multi-staged dielectric resonators has an impedance coupling relationship that the impedance becomes gradually and symmetrically smaller to both end stages.

Abstract: This invention relates to the design of a microwave component utilizing geometric shapes positioned within the channel of a waveguide structure so as to produce microwave manipulation characteristics, with associated near and far fields, whereby predetermined performance requirements may be satisfied.

Abstract: The present invention relates to a dual polarization active microwave reflector with electronic scanning, capable of being illuminated by a microwave source in order to form an antenna.

Abstract: A microwave resonator, in particular for a filter, comprising a resonant cavity having positioned therein a plane resonator element, frequency tuning means, and intermode coupling means, the resonator element being made of a dielectric material that is at least approximately in the shape of a parallelogram and being disposed transversely in the cavity in such a manner that the vertices of the parallelogram are short-circuited to one another by the conductive inner wall of said cavity. The resonator has at least one other plane resonator element made of dielectric material in a shape that is at least approximately that of a parallelogram, the resonator elements being placed close together, mutually parallel, and extending transversely to a central axis of the cavity. The frequency tuning means and the intermode coupling means are positioned between the parallel resonator elements.

Abstract: A microwave filter has a set of irises to couple cavities within the filter. A trifurcated iris comprises a central iris and a pair of peripheral irises. The peripheral irises are configured and oriented to couple a primary mode having a magnetic field in the axial direction of a filter cavity. The central iris is configured and oriented to couple a secondary mode having a magnetic field in the azimuthal direction of the filter cavity. The configuration of the trifurcated iris is further oriented to minimize the influence of higher order signals such as the TE21X mode. The peripheral iris are oriented at null points of the primary TE21X mode and the central iris is also located at a null point. An input and an output iris are configured to receive electromagnetic energy in the axial direction of the filter. The input and output irises are oriented to minimize signals in the TE21X secondary mode and any TM modes.

Abstract: A waveguide arrangement for microwaves and the like has a first waveguide composed of a material having a first thermal expansion coefficient, a second waveguide composed of a material having a second thermal expansion coefficient which is different from the first thermal expansion coefficient, and a transition element provided between the first and second waveguides for mechanical uncoupling of the different thermal expansion coefficients of both the waveguides.

Abstract: An E-plane waveguide is provided comprising a housing having opposed walls defining a waveguide channel. The waveguide includes at least two elements spaced apart in a direction along the waveguide channel and disposed between and spaced from the opposed walls, and which define a resonant cavity therebetween with the waveguide channel. At least one of the walls has first and second protrusions which are spaced apart in a direction along the waveguide channel and protrude into the waveguide channel. The spacing between the protrusions is less than half a wavelength of the resonant frequency of the resonant cavity.

Abstract: An antenna duplexer including an elongated hollow body realized with two opposed half shells is disclosed. The duplexer also includes a first opening or antenna port and a second and a third opening, or ports of the transmitter and of the receiver. A filtering structure is provided including a plurality of metal inserts available to uncouple the transmitter from the receiver. The duplexer has at least an additional portion of waveguide structured in order to keep the wave “under the cut-off frequency”, interposed between at least second or third opening and the relative end wall of the elongated body. An additional portion of wave guide includes an additional metal insert, forming part of the above mentioned filtering structure, which determines an exponential attenuation of the signal, thus nullifying the negative effects deriving from the mechanical tolerance of the hollow body.

Abstract: A waveguide arrangement for microwaves and the like has a first waveguide composed of a material having a first thermal expansion coefficient, a second waveguide composed of a material having a second thermal expansion coefficient which is different from the first thermal expansion coefficient, and a transition element provided between the first and second waveguides for mechanical uncoupling of the different thermal expansion coefficients of both the waveguides.

Abstract: A resonance device with strengthened coupling between a resonator and a transmission line without reducing an unloaded Q of the resonator. The resonance device includes a micro-strip line as a transmission line, which has a dielectric substrate, a main conductor, and an earth conductor, both of which are formed on the dielectric substrate, and a resonator disposed near the main conductor of the micro-strip line to be electromagnetically coupled thereto. At a part of the main conductor of the micro-strip line where it is coupled to the resonator, an electrodeless portion such as a slit is formed in a direction substantially parallel to a signal-propagating direction.

Abstract: In a waveguide twist having a torsion element with at least three individual parts situated adjacent to each other and rotatable around an axis of the torsion element, in which each of the individual parts has a central passage hole with a cross-section corresponding to the open cross-section of the waveguides, and in which the passage holes of the individual parts in a non-rotated condition of the torsion element are aligned with each other, a recess is formed in one face of each of the individual parts, the extent of the recess in circumferential direction corresponding to a specified angle of rotation; from the other face of the individual parts a pin extends in an axial direction; and in a mounted position of the torsion element a pin projecting from one individual part engages in the recess located in the face of the adjacent individual part.

Abstract: A conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block, for example at an end surface. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode may be connected to the conducting film formed on the outer surface of the dielectric block, for example at a side surface. The coupling electrode is non-linear, preferably L-shaped.

Abstract: A conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on a side surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the coupling electrode extends toward the conducting film formed on the opposite side surface and one end surface of the dielectric block. The above structure allows an increase in the degree of freedom in the design of the characteristics including the resonance frequency and unloaded Q of the dielectric waveguide resonator.

Abstract: A band-pass filter for a waveguide, which additionally serves as a blocking filter for the concerted suppression of interference frequencies. In addition to a centrally arranged aperture (3), a waveguide aperture has two identically designed apertures (4), which are laid out for natural resonance for an interference frequency f (ind S1) to be blocked by the waveguide filter, and are arranged symmetrical to the central aperture opening (3). In waveguide devices, the invention is used to meet the statutory frequency specifications and simultaneously suppress interference frequencies.

Abstract: A microwave resonator, particularly for use in cellular telecommunications, comprising a hollow electrical conductor defining a resonant cavity and a substantially cubic member located within the cavity. The substantially cubic member has a high dielectric constant compared with the remainder of the cavity.

Abstract: Asynchronously-tuned coupled resonator cavities are implemented having a minimum set of inter-resonator couplings, wherein the filter design incorporates only series and parallel couplings. By way of example, 8th order filter topologies having three transmission zeros, no cross-couplings, and only eight series and/or parallel couplings can be achieved.

Abstract: The invention relates to a device for rotating through a predefined angle the polarization of a polarized electromagnetic wave propagating in a first waveguide. According to the invention, the device comprises a second waveguide having a lateral port, the polarized electromagnetic wave propagates between a port of the first waveguide and the lateral port of the second waveguide via a coupling orifice that is smaller than the cross-section of the first waveguide and whose geometry is adapted to provide electromagnetic coupling between the first waveguide and the second waveguide, and the other port of the second waveguide is on a face perpendicular to the lateral port.

Abstract: A nonradiative dielectric waveguide filter of the present invention permits the manufacturing process including the production of a dielectric strip to be simpler. The filter can be formed by a pillar dielectric strip. The nonradiative dielectric waveguide filter includes resonators, input-output connection units, and cut-off regions, in which the upper and lower conductor plates and a dielectric strip disposed therebetween form the filter. In one example, the main signal-transmitting mode is the LSM mode; a groove having a bottom and conductor walls is disposed in a position in which the conductor plates are opposing; the resonator is formed by fitting the dielectric strip into the groove; and the cut-off regions are formed by second grooves formed in the conductor plates adjacent to the dielectric strip.

Abstract: A radio frequency amplifier includes a waveguide filter positioned between a first and a second amplifier circuit, which reduces the distortion between the amplifier circuits. The waveguide includes a main body having a cavity.

Abstract: A dielectric duplexer or multiplexer in which a conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode is either connected to the conducting film formed on the outer surface of the dielectric block or terminated inside the dielectric block.

Abstract: A waveguide filter having a stepped transformer area on the input and/or output sides, with at least one band-stop filter composed of geometrically closely spaced stop elements integrated into this stepped transformer area. These features make it possible to build waveguide filters with a high edge steepness and a short overall length.

Abstract: A dielectric duplexer or multiplexer in which a conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode is either connected to the conducting film formed on the outer surface of the dielectric block or terminated inside the dielectric block.

Abstract: A conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode is either connected to the conducting film formed on the outer surface of the dielectric block or terminated inside the dielectric block. The above structure allows an increase in the degree of freedom in the design of the characteristics including the resonance frequency and unloaded Q of the dielectric waveguide resonator.

Abstract: A waveguide filter is provided having a plurality of asymmetrical corrugated resonators. The filter may also include an input section and an output section including a low-pass filter unit and a transformer unit. The low-pass filter unit includes a plurality of symmetrically corrugated slots, and the transformer unit includes at least one stepped transformer section for matching the filter to an external waveguide line. Each of the asymmetrically corrugated resonators may include a pair of opposed slots of different depth, a long slot and a short slot. The resonators provide at least one reflection zero and two transmission zeros to the frequency response of the filter, thus providing high-pass, band-pass and low-pass filter properties in a single filter structure.

Abstract: A bandpass filter makes use of at least one waveguide cavity that is thermally compensated to minimize drift of a resonant frequency of the cavity with thermal expansion of cavity components. The compensation relies on deformation of the shape of at least one cavity surface in response to thermally-induced dimensional changes of the cavity. A control rod is used to limit the movement of a point on the deformed surface, while the rest of the surface moves with the thermal expansion. The control rod is made of a material having a coefficient of thermal expansion that is significantly different than that of other filter components. The rod may also be arranged to span more thermally expandable material than defines the filter such that, as the filter expands, the point of deflection is moved toward the interior of the filter beyond its original position.