Abstract: In a ferrite switchable microwave device, a magnetic structure is formed in a nearly continuous closed-loop configuration of a single crystal material, or of a material exhibiting the magnetic properties of single crystal materials (quasi-single crystal materials). A magnetization M is induced in the structure. The toroidal shape of the structure in combination with the properties of the magnetic material results in a device which exhibits virtually no hysteresis. The device is operable either in a fully magnetized state or in a partially magnetized state. In a fully magnetized state, the device operates in the region of magnetic saturation. The absence of hysteresis in the device enables switching between the positive and negative magnetic saturation points with very little energy. In a partially magnetized state, the device provides a variable magnetization M between the two saturation points.

Abstract: An enhanced tunable coaxial cavity filter that may be tuned while it is shorted. The coaxial cavity filter may have one or more cavities. One or more of the cavities may include a switch for shorting the cavity. When a plurality of cavities are implemented, the cavities may be coupled in series such that shorting one of the cavities effectively shorts the entire filter. The switch for shorting the cavity may include a solenoid switch. The solenoid switch may be disposed within a stator that is stationary with respect to a rotatable rod for tuning the filter. Such a design has shown to be extremely robust for wear, vibration, and other considerations, even in high stress environments.

Abstract: Dielectric parts 12 which become resonators are fitted in holes formed in a dielectric substrate 11 and magnetic parts 13 for setting resonance frequencies of the dielectric parts 12 are also fitted in holes formed in the dielectric substrate 11. With such construction in which the dielectric parts are fitted in the holes of the dielectric substrate, the physical preciseness of a high frequency filter is improved. Further, by fitting not only the dielectric parts 12 but also the magnetic parts 13 in the holes of the dielectric substrate 11, it is possible to form the high frequency filter operating in a frequency band of several tens GHz as a micro wave integrated circuit to thereby improve the uniformality and mass-producibility of the high frequency filter.

Abstract: A plurality of end caps engagable with a microwave cavity each have an underside configured differently to cause the microwave cavity to have different electrical responses depending on which end cap engages the microwave cavity. A microwave device includes a cylindrical cavity and an end cap movable within the cavity to change its axial position within the cavity thereby varying the volume and the electrical response of the cavity.

Abstract: The present invention relates to a tuning device in radio filter equipment for mobile telephony in which one or more cavities in the equipment should be tuned to the right frequency. The invention also relates to a tuning plate including a number of such tuning devices. The tuning device preferably includes regular or square formed depressed parts in the tuning plate. The depressed part converges each to a square formed central plate which is provided with an elevation or bulb. By turning a tuning screw on the equipment a force is developed on the plate and the surrounding depressed parts. This implies that the tuning can be made automatically, more secure and with less risk for intermodulation.

Abstract: A superconducting notch or band reject filter arrangement includes a superconducting dielectric resonator and a waveguide arrangement including a microstrip line to which the resonator is connected. The resonator is a parallel-plate resonator with a chip of a non-linear dielectric material device on which superconductors are arranged and the waveguide arrangement includes a contact device or a coupling device, the resonator being connected to the contact device of the waveguide arrangement in such a way that electric contact is provided, and the filter arrangement is frequency tuneable. Through the arrangement, the insertion losses are low.

Abstract: The dielectric notch filter of the invention includes: a transmission line for transmitting a high-frequency signal; input and output terminals provided at both ends of the transmission line; a ground conductor for supplying a ground potential; and a dielectric resonator connected to the ground conductor and the transmission line. The dielectric notch filter further includes an impedance matching element connected to the ground conductor and the transmission line in parallel with the dielectric resonator. The dielectric resonator includes: a cavity connected to the ground conductor; a dielectric block provided in the cavity; a coupling device coupled with an electromagnetic field produced in the cavity; and a coupling adjusting line for connecting the coupling device to the transmission line and for adjusting the degree of electromagnetic coupling.

Abstract: A tuning screw with a slotted tip suited for microwave and millimeter wave applications. The slotted tip provides compression upon insertion into the conductive device and the spring character of the screw tip fingers press against the conductor walls ensuring good electrical connection.

Abstract: The present invention provides an electronically tunable resonating apparatus which uses a tunable dielectric material which is biased by an electric field to alter the resonant frequency in a resonating cavity. The electrodes which apply the electric field are connected to a variable voltage source. The electrodes can therefore apply a plurality of electric field strengths and provide a range of resonant frequencies in the resonating apparatus. The resonating apparatus is particularly useful for microwave and millimeterwave electromagnetic energy.

Abstract: A tunable local oscillator (10) with a tunable circuit (12) that includes a resonator (16) and a transistor (14) as an active element for oscillation. Tuning of the circuit (12) is achieved with an externally applied dc bias (22, 24) across coupled lines (20) on the resonator (16). Preferably, the resonator (16) is a high temperature superconductor microstrip ring resonator with integral coupled lines (20) formed over a thin film ferroelectric material. A directional coupler (38) samples the output of the oscillator (14) which is fed into a diplexer (40) for determining whether the oscillator (14) is performing at a desired frequency. The high-pass and low-pass outputs (42, 44) of the diplexer (40) are connected to diodes (48, 46) respectively for inputting the sampled signals into a differential operational amplifier (50). Amplifier (50) compares the sampled signals and emits an output signal if there is a difference between the resonant and crossover frequencies.

Abstract: A multiple-mode dielectric resonator in which a combined dielectric block formed of a plurality of dielectric elements combined into a crossed shape is used to cause three resonance modes along a plane defined by two of the dielectric elements, and in which the resonant frequency of each mode is determined, or a multiple-mode dielectric resonator in which the degree of coupling between predetermined resonance modes is determined. If first and third resonance modes are two TM110 modes having different lines of symmetry of electric field distributions, and if a second mode is a TM111 mode, dielectric-cut portions are formed in the combined dielectric block, for example, at positions where the electric field distribution of the first resonance mode is concentrated while the electric field distributions of the second and third resonance modes are not concentrated, thereby selectively determining the resonant frequency of the first resonance mode.

Abstract: A dielectric resonator capable of adjusting a resonance frequency, reducing occurrence of a mode jump if it is applied to an oscillator and being manufactured at a low cost. The dielectric resonator has a pair of upper and lower opposing conductive plates; a dielectric substrate disposed between the conductive plates; a first electrode formed on one surface of the dielectric substrate, the first electrode having a first opening; a second electrode formed on another surface of the dielectric substrate, the second electrode having a second opening corresponding to the first opening so that a resonator is formed by a portion of the dielectric substrate disposed between the first and second openings; and a variable capacitor located in a portion of the dielectric substrate in which an applied electromagnetic field is confined in and around the resonator.

Abstract: A radio frequency oscillator having: a resonant circuit; a gain element coupled in feedback relationship with the resonant circuit; and a variable reactance device, such as a varactor diode, adapted for coupling to a control signal for varying the reactance of the device. The variable reactance device is coupled to the resonant circuit with a coupling factor less than one. The resonant circuit comprises a planar microstrip transmission line structure. The varactor diode is coupled to the microstrip transmission line through a strip conductor disposed adjacent to, and dielectrically spaced from, a strip conductor of the resonant circuit. In one embodiment, the strip conductors are disposed in a side-by-side, dielectrically spaced relationship. In another embodiment, the strip conductors are disposed in a face-to-face, dielectrically spaced relationship.

Abstract: An electromagnetic wave component uses one or more diaphragms secured to the interior of a waveguide structure to tune its resonant frequency, with each diaphragm engaged by one or more adjustment members that deform it. The adjustment members are preferably screws that are threaded through the structure to push and/or pull on the diaphragms, thereby tuning the electromagnetic wave component. The shift in the resonant frequency of the electromagnetic wave component due to temperature-induced dimensional changes is mitigated if the materials used for the diaphragm, the adjustment members and the structure which houses the diaphragm are chosen to have an appropriate combination of thermal coefficients of expansion.

Abstract: A device for changing the operating frequency of a microwave filter is mounted in a wall of a cavity of the filter. The device has a bellows that is located inside the cavity. The bellows contains an elongated member that extends outside the cavity to an actuator. The actuator can be temperature dependent and moves the elongated member either further into or further out of the cavity as desired. An interior end of the elongated member can be connected to the bellows or it can simply be in contact with the bellows without being connected. When the elongated member is in contact with the bellows and is not connected, when the elongated member moves outward, the bellows will return to a rest position due to its inherent spring. The bellows is sealed from an interior of the cavity. Filters using the device have one device located primarily for each mode in each cavity of the filter.

Abstract: A reconfigurable filter system designed using micro-elecro-mechanical (MEM) switches is disclosed. The filter comprises a transmission line with one or more filter stubs coupled to the transmission line by MEM switches. The impedance of the filter system is altered by selectively opening and closing the MEM switches, which alters the filter characteristics of the filter system. Alternatively, the characteristics of the filter system are altered by using the MEM switches to selectively alter the length of filter stubs attached to the transmission line.

Abstract: A band-rejection filter (1) comprising transmission line resonators (2, 3) further comprises switching means (7, 8) to provide an electrical connection between each transmission line resonator and a certain fixed potential in response to a certain control signal. The fixed potential is advantageously the ground potential, whereby the control signal causes the resonators to be shunted and the frequency response of the filter to be changed into a low-pass-type frequency response.

Abstract: Two helical resonator filters for applications in wireless and satellite communication systems. The present invention provides for single mode and dual mode microwave filters that employ evanescent waveguide cavities loaded with helical resonators. The structure of the present invention provides for a high Q factor in a miniature package. Two helical resonator filters are well adapted for use in wireless and satellite communication systems. The present invention provides for miniature filters utilizing single mode, high dielectric constant material loaded helical resonators, as well as higher order dual mode helical resonator loaded cavities. Both configurations can be used to realize advanced filters with non-adjacent coupling. The helical resonators may be loaded with high dielectric constant materials or ferrite materials for additional miniaturization and tunability. Either voltage or current tuning may be provided by the single mode and dual mode microwave filters.

Abstract: The voltage-controlled variable-passband filter in accordance with the present invention is structured so that conductive patterns, R, L, and C, and other circuit elements are embedded in a ceramic substrate. Within this substrate is also embedded an insulating layer made of the same ceramic material, the capacitance of which changes in response to an electric field applied thereto. On one surface of the insulating layer is provided a control electrode, and on the other surface are provided adjacent to one another a resonator pattern, to which high-frequency signals are applied, and a ground pattern. Accordingly, two capacitors connected in series are formed between the resonator pattern and the ground pattern, and the capacitance of these series capacitors can be adjusted by an integrated circuit mounted on the ceramic substrate, thus reducing size and weight, and simplifying adjustment.

Abstract: In a small transmission line type high-frequency circuit element that has small loss due to conductor resistance and has a high Q value, an error in the dimension of a pattern, etc. can be corrected to adjust element characteristics. An elliptical shape resonator (12) that is formed of an electric conductor is formed on a substrate (11a), while a pair of input-output terminals (13) are formed on a substrate (11b). Substrate (11a) on which resonator (12) is formed and substrate (11b) on which input-output terminal (13) is formed are located parallel to each other, with a surface on which resonator (12) is formed and a surface on which input-output terminal (13) is formed being opposed. Substrates (11a) and (11b) that are located parallel to each other are relatively moved by a mechanical mechanism that uses a screw and moves slightly. Also, substrate (11a) is rotated by the mechanical mechanism that uses a screw and moves slightly around the center axis of resonator (12) as a rotation axis (18).

Abstract: A radio-frequency filter for a radio apparatus operating on two frequency bands is based on impedance step resonators, wherein two interconnected resonator sections (L2, L1) having different impedances are dimensioned such that the resonator's fundamental resonating frequency (f0) is on the lower operating frequency band and a certain harmonic resonating frequency (fs1) is on the higher operating frequency band. The filter may have separate ports (port 2, port 3) for the signals of the different frequency bands and they can be isolated from each other using additional filtering (LC1, LC2).

Abstract: A method of tuning a summing network of a base station and a band-pass filter provided in such base station. Tuning is performed by arranging a moveable part made of a low-loss dielectric material or ferrimagnetic material in a space between an inner conductor and a tubular conductor in a coaxial cable, the width of the cross-section of the moveable part being different from its length, and tuning the summing network by adjusting the phase angle reflecting from the connector by turning the moveable part about an axle which intersects the cross-section substantially perpendicularly, whereby the distance between the moveable part and the inner conductor and/or between the moveable part and the outer conductor changes.

Abstract: The present invention relates to an integrated radio unit used in radio base stations in mobile telephony. One housing is provided for all elements of an integrated radio unit, including a functional unit and a center conductor plate. The combination of the cover and base of the housing form protective cavities for the functional unit and, simultaneously, a cavity whose shape, in combination with the center conductor plate, helps form the filter characteristics of the integrated radio unit. The design of the housing reduces the need for extensive connections between elements and also provides a cavity which, in combination with the center conductor plate, will act as a filter.

Abstract: A switched resonator formed from a series capacitor and a single microstrip transmission line with a plurality of RF switches to connect it to ground along its length. The microstrip transmission line is grounded at one end and the RF switches are used to tune its length. The other end of the microstrip transmission line is connected to the capacitor to form a resonator. The resonant frequency of the resonator is varied by grounding the center conductor through RF switches connected to ground at different points along its length, which effectively varies the electrical length of the transmission line connected to the capacitor thereby forming a switched resonator. The switched resonator is suitable for use with a single VCO to provide relatively wideband tuning of the significantly reduced size due to the use of a single VCO.

Abstract: The tunable filters of the present invention incorporate tunable dielectric materials (e.g., bulk and thin film ferroelectric and paraelectric materials) in contact with segments of resonators that are at an RF voltage maximum to alter the pass band or stop band characteristic of an RF signal outputted by the filter. The biasing circuitry in contact with the tunable dielectric material can include components for inhibiting or retarding the coupling of RF energy to the biasing circuit.

Abstract: A method (100) for mechanically tuning a VCO that has a resonant stripline having vias in predetermined locations connected through a circuit board to ground. This includes a step (104) of measuring the operating frequency of the VCO. A following step (106) includes calculating an amount of frequency shift needed to achieve a desired frequency. A following step (108) matches the amount of frequency shift needed to values in a look-up table of frequency shifts versus via locations to determine which vias locations will provide the proper amount of frequency shift. A last step (110) includes mechanically disconnecting from ground the via locations indicated in the third step such that the desired frequency is achieved. This method (100) of tuning allows VCO frequency adjustment after final assembly avoiding problems of frequency shifts that can occur due to the placement of a metal lid on the circuit board after assembly.

Abstract: An adjustable RF microwave tuning post for use in an RF cavity is disclosed. It is comprised of a flexible integrally-formed hollow tuning post disposed in the RF cavity. A drive shaft extending internally of the tuning post is provided to vary the dimensions of the tuning post. The drive shaft is connected to the tuning post at the top end thereof and connected at the other end of the drive shaft to an adjusting nut. The tuning post is made flexible by the use of bellows, which in a preferred embodiment of the invention is located along the side walls thereof.

Abstract: An electromagnetic wave component uses one or more diaphragms secured to the interior of a waveguide structure to tune its resonant frequency, with each diaphragm engaged by one or more adjustment members that deform it. The adjustment members are preferably screws that are threaded through the structure to push and/or pull on the diaphragms, thereby tuning the electromagnetic wave component. The shift in the resonant frequency of the electromagnetic wave component due to temperature-induced dimensional changes is mitigated if the materials used for the diaphragm, the adjustment members and the structure which houses the diaphragm are chosen to have an appropriate combination of thermal coefficients of expansion.

Abstract: A tuning mechanism for tuning a resonant circuit is provided. The tuning mechanism comprises a spring pin having a superconductive, dielectric or magnetic tuning tip attached thereto. The spring pin is slidably inserted into a filter package wall through a mating hole. A mechanism is provided for adjusting the position of the tip within the electromagnetic field above the filter element. The tip may be shaped, thus allowing adjustment of both the height of the tip above the filter element and the position of the tip in a plane parallel to the plane of the filter. Optionally, the spring pin may include an offset to allow close spacing of the tips along with wider spacing of the actuator end of the pin.

Abstract: A combination notch/bandpass filter uses first and second adjacently-located cavities in the conductive housing to respectively provide a tunable, first-stage notch filter and a second-stage bandpass filter. An opening in a wall provides a passage for energy from the first cavity to the second cavity. In the first cavity, a resonator is located adjacent the opening, along with a notch-filter tuning member having one end arranged opposite the resonator and spaced therefrom by a distance to permit the wide end of a coupler to be suspended therebetween. An elongated portion of the coupler carries filtered energy from the first cavity to the second cavity.

Abstract: A first electrically conductive layer whose thickness is equal to or smaller than the skin depth of the radio wave used for communication, a dielectric layer whose permittivity is changed by application of electric field, and a second electrically conductive layer whose thickness is equal to or smaller than the skin depth of the radio wave used for communication are sequentially stacked near a resonance element which is formed on the front surface of a dielectric substrate having a ground layer formed on the rear surface thereof. The effective permittivity of the dielectric layer is changed in a wide range by changing a voltage applied between the first and second electrically conductive layers to change the electric field applied to the dielectric layer. As a result, the impedance of the resonance element is changed, and when a plurality of resonance elements are arranged closely to each other to construct a filter, the coupling degree between the resonance elements is changed.

Abstract: A laminated electronic component has a structure in which an micro-strip line (MSL) is formed in a first dielectric layer, and a first ground layer and an adjustment pattern layer are formed on the top surface and the base surface of the first dielectric layer, respectively. A second dielectric layer is formed between the adjustment pattern layer and a second ground layer, comb teeth-shaped parallel electrodes having an area larger than that of the MSL is formed at a position opposed to the MSL in the adjustment pattern layer. A slit is formed not to be opposed to the MSL in the second ground layer and to be opposed to the connection points of the parallel electrodes. By emitting a laser beam from the direction of the second ground layer through the slit and the second dielectric layer, and separating the connection points of the parallel electrodes, the capacitance between the MSL and the ground can be adjusted in steps, which increases the resonant frequency of the MSL.

Abstract: For tuning a summing network of a base station which has connectors, conductors and a filter, including input connectors for receiving signals supplied by radio transmitters of the base station, and output connectors for feeding the filtered signals further to an antenna, a bandpass filter is provided. The summing network can be optimized on the correct frequency, by adjustment of the electric length of an output connector of the filter.

Abstract: In a magnetically-tunable resonator, a wave-guiding structure comprising an electromagnetic frequency filter, or component of such a filter, is placed in sufficient proximity with a magnetic structure so as to be gyromagnetically coupled therewith. The resonator is supportable of two fundamental normal modes of propagation which, in the absence of magnetic interaction are even and odd with respect to the resonator center plane of symmetry. Each normal mode possesses a spectrum of resonance frequencies. When the magnetic structure is magnetized, the formerly even and odd modes become mixed due to gyromagnetic interaction, and the resulting wave fields become elliptically polarized. With appropriate design such that the identities of the modes are preserved under conditions of resonance, this in turn results in a nonreciprocal reinforcement action in the resonator, which leads to the desired shift in resonance frequency in at least one of the two normal modes.

Abstract: A dielectric resonator encased within a pressure enclosure establishes the operating frequency of a microwave circuit. The enclosure is supplied with a pressurized gas and the pressure within the enclosure is varied as a function of the deviation of the operating frequency from a desired value. For more precise control the enclosure is preferably immersed in a cryogenic cooling system.

Abstract: A low noise wide tuning bandwidth voltage controlled oscillator employs a resonator circuit formed from at least two microstrip lines which are electromagnetically coupled to one another. Each of the microstrip lines has one end electrically coupled to circuit ground to provide a substantially inductive resonator circuit which is substantially immune to parasitic end effects and radiation loses. The frequency of the voltage controlled oscillator circuit is controlled by a variable capacitance varactor circuit coupled to at least one of the microstrip transmission lines. The resonator circuit is well suited for use with a bipolar transistor configured as a negative resistance oscillator.

Abstract: In the present invention, a tuning circuit which includes a controllable switch based on a diode (D1), for example, and which is connected in parallel with a resonator, is located between the low impedance end of a center conductor (11) of a quarter wavelength resonator and ground, whereupon resonant frequency tuning is based mainly on a change in the inductance of the resonator. Voltages and power affecting a tuning circuit realized according to this invention are essentially smaller than in a circuit in which the capacitive load of a resonator is tuned by means of a similar tuning circuit located at the high impedance end of the resonator.

Abstract: TM.sub.0i0 mode (i=1, 2, 3, . . . ) planar high temperature superconductor resonators useful in high temperature superconducting filters, filter banks and multiplexers comprise a shaped high temperature superconductor film and a high temperature superconductor ground plate deposited on opposite sides of a dielectric substrate, wherein the shaped high temperature superconductor film has an aperture in the center thereof and has a shape selected from the group consisting of circles and polygons.

Abstract: A filter has a shell construction including a connection surface and a bar-like resonator in the shell construction. The bar-like resonator has an initial section having one end region thereof connected to the connection surface of the shell construction and an opposite end region. A substantially straight and elogate intermediate section extends from the opposite end region of the initial section to an end and a turning-point section extends from the end of the intermediate section to an end. A substantially straight and elongate end section has one end connected to the end of the turning-point section so as to extend adjacent to the intermediate section and supporting means connect to the connection surface of the shell construction for supporting the bar-like reasonator at least at one of the end section and turning-point.

Abstract: A resonator includes a substrate to which are attached trimmable capacitance and inductance portions which together with a varactor and transistor form an oscillator circuit. The substrate mounts orthogonally in a slot on an oscillator board to reduce microphonic effects from a cover that otherwise would degrade the oscillator performance.

Abstract: A tuner including a shaft extendible through an aperture extending completely through a jacket of the tuner. The tuner includes a shaft tensioning and grounding structure and a tuning material holder comprising a cup-shaped structure with a clasping element.

Abstract: A tunable cavity resonator for a frequency filter has a shell in a wall of which is mounted an adjustable-length conductor which has an outer pipe fixed at an outer end to the wall, and an adjusting element made of a flexible material. An adjuster is provided for adjusting the length of the conductor. The adjusting element is partially everted axially of the outer pipe, and has opposite ends connected to the pipe and the adjuster. Axial movement of the adjuster causes half as much change in the effective axial length of the conductor.

Abstract: An electromagnetic filter has a unitary filter body defining a number of cavities. A cover for the filter body has several resonators attached to it which are located in the cavities when the cover is attached to the filter body. The cover has a recess into which a transmission line is placed. Passageways through the cover connect the transmission line with coupling mechanisms mounted on the cover adjacent the resonators. The resonators have a generally toroidal shape and the coupling mechanisms are shaped to provide the desired coupling between the transmission line and the resonators. An adjustable capacitor attached to the coupling loop has a passageway through its housing to eliminate moisture from the capacitor. The resonator and cavities may be tuned by use of a tuning mechanism which is also designed to minimize moisture which might prevent movement of the tuner during tuning.

Abstract: A base station summing network having at least two transmitter branches made turnable by providing filters in the branches with adjusters, so that each branch can be separately adjusted.

Abstract: A tuning assembly for an RF filter having an internal cavity. The tuning assembly is mounted on one of the filter walls and comprises an adjustment screw threadedly secured in the wall and having an inner end in the cavity and an outer free end external of the wall, a generally circular tuning plate, and a formed in situ molded connector fixedly securing the tuning plate to the inner end of the screw and for preventing relative movement therebetween. A formation is provided at the free end of the adjustment screw for facilitating rotation of the adjustment screw relative to the wall so that the tuning plate may be moved within the cavity toward and away from the wall.

Abstract: An inductive strip waveguide band-pass filter includes a conductive movable wall which can be set to various positions to allow a varying "A" dimension, thereby setting controllably the center frequency of the filter over a predetermined range. If the inductive strip filter includes multiple synchronized resonant cavities, the resonant cavities remain synchronized for all positions of the movable wall. The position of the movable wall can be set manually or by a motorized control mechanism.

Abstract: A microstripline resonator in which a desirable resonant frequency can be adjusted with less deterioration in Q and less production process steps is characterized in that a hollowed-out portion is formed in an electrode portion provided on an insulating substrate base. A width-narrowed portion is provided between the side edge of the electrode portion and the hollowed-out portion for adjusting the resonant frequency of the microstripline resonator.

Abstract: A dielectric resonator includes a cylindrical hole formed in the intersection of two resonator elements forming a TM dual-mode dielectric resonator element. The hole extends in a direction across the thickness of the TM dual-mode dielectric resonator element. Furthermore, a quadrangular pyramid-shaped hole having a closed end is formed in each connecting part between each resonator element and a cavity wall so manner that each hole extends from the outer surface of the cavity wall toward the inner portion of each resonator element, wherein the inner wall of each hole is covered with a conductor electrically connected to a cavity conductor. The shapes of the above holes are determined so that the TM dual-mode dielectric resonator element has the same resonance frequency for both TM 110 and TM 111-modes.

Abstract: A ferrite resonating device operative for example as an oscillator or filter includes a mechanism for mechanically varying the position of a permanent magnet while maintaining a fixed main gap in which a ferrite resonating element is placed so that wide tuning can be achieved while maintaining electrical parameters substantially constant.

Abstract: A stepwise regulated filter includes a resonator structure and a coupling connected to the resonator structure. The resonating frequency of a transmission line (HX1) acting as a resonator may be switched between at least three values. The switching is implemented using coupling elements (SL1, SL4) which are in an electromagnetic coupling (M2, M3) with the resonator (HX1). The potentials of the coupling elements (SL1, SL4) are affected by PIN diodes (D1, D2) acting as switches. A RF power signal, which is coupled from the resonator (HX1) to the coupling elements (SL1, SL4), is applied to both terminals of at least one diode (D1) with the same phase and power. Then the voltage across the diode (D1) cannot, in the blocking state, rise to a level that would cause undesirable mixing results or would damage the diode (D1).