Abstract: The present invention provides a small, thin filter circuit showing a desired filter characteristic which is highly accurate, and producible with a high efficiency. The filter circuit includes a pair of dielectric insulating layers 2 and 3, upper and lower, each having a ground pattern 11 (16) formed on the main side thereof, and an inner wiring layer 4 formed between the dielectric insulating layers 2 and 3 and having capacitively coupled resonator conductive patterns 6 and 7 each connected at one end thereof to the ground patterns 11 and 16 via inter-layer connecting vias 12 and open-circuited at the other end.

Abstract: A tunable electrical filter constructed pursuant to the teachings of the present invention includes: (a) a plurality of resonator units coupled between an input locus and an output locus; and (b) a plurality of tunable dielectric varactor units; respective individual varactor units of the plurality of varactor units being coupled between respective pairs of the plurality of resonator units, coupled between the plurality of resonator units and the input locus, and coupled between the plurality of resonator units and the output locus.

Abstract: A tuning circuit, as for a television receiver or video recorder, employs switchable tuning circuits including micro-electronic electro-mechanical switches for selecting the ones of an array of capacitors and/or inductors as is useful in tunable circuits. The array of capacitors and/or inductors and micro-electro-mechanical switches of the switched tuning matrix is formed on an integrated circuit or an electronic circuit substrate along with amplifiers and other electronic elements of the tuning circuit for which the switched tuning matrix is employed. The switchable capacitance and inductance matrices are well suited for use in the resonators employed in the pre-selector filters, post-selector filters and oscillators of electronic tuners, such as those employed in television receivers and video recorders.

Abstract: A method of tuning a microwave or RF circuit is given which comprises the steps of taking a microwave or RF circuit (20) located in a casing (57), said casing comprising a housing portion (32) and a window portion (50), said window portion (50) being substantially conducting at microwave/RF frequencies, and comprising at least one area that is substantially transparent at optical frequencies and, directing a laser beam (66) onto said microwave or RF circuit through said window portion (50) so as to alter the material properties of selected areas of said microwave or RF circuit (20). This permits microwave and RF circuits, including microwave filters, to be tuned without the need for tuning screws.

Abstract: There is disclosed a planar filter which can variably control a pass frequency band with a high precision and which is superior in skirt property and little in ripple. A planar filter member and tuning member are disposed opposite to each other via a predetermined gap. The filter member is structured in such a manner that an input/output portion formed of a superconductor and a plurality of resonance elements are formed on a substrate. The tuning member is structured in such a manner that on the surface of a magnetic plate with a permeability changing by an applied magnetic field, a plurality of dielectric thin films, and a plurality of electrodes for applying electric fields to the dielectric thin films are arranged. Each of the dielectric thin films is disposed in a position opposite to a gap between the resonance elements of the filter member, or a gap between the filter member and the input/output portion.

Abstract: A low-pass or band-rejection filter for microwave frequencies has a substantially planar structure and is constructed of a transmission line having inductor portions and wider capacitance portions. The inductor portions are designed as linear microstrip elements having widths being varied by making areas at the sides of the linear elements superconducting. In changing the widths of the transmission line also the inductances thereof are changed accordingly. The areas at the sides of the microstrip elements include rather narrow areas located directly at the central, normal metal conductor. These narrow areas have in the non-superconducting state some electrical conductivity which can be small but still not quite insignificant in relation to that of the metal conductor.

Abstract: An electronic filter includes a substrate, a ground conductor, an input, an output, a first microstrip line positioned on the substrate and electrically coupled to the input and the output, and a first tunable dielectric varactor electrically connected between the microstrip line and the ground conductor. The input preferably includes a second microstrip line positioned on the substrate and including a portion lying parallel to the first microstrip line. The output preferable includes a third microstrip line positioned on the substrate and including a portion lying parallel to the first microstrip line. The first microstrip line includes a first end and a second end, the first end being open circuited and the varactor being connected between the second end and the ground conductor. The filter further includes a bias voltage circuit including a high impedance line, a radial stub extending from the high impedance line, and a patch connected to the high impedance line for connection to a DC source.

Abstract: A circuit is provided wherein the electronic properties of the circuit are varied by a magnetic actuator. The circuit includes a fixed substrate and a movable substrate. The magnetic actuator comprises a magnetic driver on an upper surface of the fixed substrate that is substantially overlapped by an HTS reaction plate on the lower surface of the fixed substrate. A tuning current applied through a continuous strip of HTS material in the magnetic driver induces a repulsive magnetic force causing the movable substrate to move with respect to the fixed substrate.

Abstract: A desired performance characteristic of an electrical circuit employing a strip conductor is achieved by placing a fluid having a selected dielectric property in contact with at least a portion of the strip conductor, such that the dielectric property of the fluid effects one or more transmission characteristics of the conductor. In one embodiment, the circuit performance is measured and the dielectric property of the fluid adjusted, e.g., in an iterative process, until the desired performance characteristic of the circuit is achieved.

Abstract: A resonator and method of tuning the same comprises at least one resonator wherein each resonator includes a tuning element coupled thereto. The tuning element may be physically attached to the resonator or may be positioned adjacent thereto. The tuning element is trimmed to change the frequency characteristic of the resonator by a slight amount. The width of the tuning element is less than the width of the resonator element of the microstrip filter so that trimming of the tuning element can be conducted with precision.

Abstract: A micro-resonator ferrite microstrip coupling filter that has reduced susceptibility to variations in the manufacturing process, as well as from changes due to mechanical or environmental stress, and allows for an assembly process that can be easily automated. The filter comprises bottom and top substrates with conductive ground planes on one side of the substrates and microstrip conductors on the other side of the substrates, with the conductors of both substrates being orthogonal to each other. A circuit block is disposed between the bottom and top substrates such that the circuit block contacts the sides of the substrates containing microstrip conductors. Multiple YIG spheres are inserted into round orifices on the circuit block and positioned between the bottom and top substrates. A magnetic field is applied orthogonally to the conductors.

Abstract: A patch filter element has an electrically-insulating substrate with an electrically conductive region on a first surface of said substrate, and a slot such as a crossed slot dividing the conductive region into a plurality of triangular sections. A mode coupling device, such as a cutout corner of a triangular section, induces orthogonal modes of vibration of an electromagnetic field about the plurality of sections. The ferroelectric oxide is disposed in the slot for adjusting a dielectric constant of the oxide in accordance with a bias voltage applied across the slot between adjacent ones of the sections for turning the patch filter element. Metallic walls may be constructed along edges of the slot for increased capacitance.

Abstract: A method is provided for operating a duplexer including a first tunable bandpass filter, a second tunable bandpass filter and means for coupling the first bandpass filter and the second bandpass filter to an antenna. The method comprises the steps of tuning the first tunable bandpass filter to provide a passband corresponding to an assigned transmit frequency, and tuning the second tunable bandpass filter to provide a passband offset from an assigned receive frequency, when the duplexer is operated in a transmit mode. When the duplexer is operated in a receive mode, the first tunable bandpass filter is tuned to provide a passband offset from an assigned transmit frequency and the second tunable bandpass filter is tuned to provide a passband corresponding to the assigned receive frequency.

Abstract: In a method for manufacturing a filter including a plurality of resonators arranged in series, a shape of the resonators and a number of the resonators are determined, so that an amount of additional coupling coefficients between the resonators except for two adjacent ones of the resonators is smaller than a predetermined value. Then, an initial coupling coefficient function is calculated with respect to a distance between two adjacent ones of the resonators, and is set in a coupling coefficient function. Then, coupling coefficients between the resonators are calculated for desired filter frequency responses, and distances between the resonators having the calculated coupling coefficients are calculated in accordance with the coupling coefficient function. Then, a layout of the filter having the resonators with the calculated distances is designed, and a tentative filter is manufactured.

Abstract: A high-frequency filter device including at least one filter to be connected to a high-frequency stage of a wireless apparatus, in which the filter includes a voltage-controlled variable frequency resonance element which comprises a resonance element and a voltage-controlled variable impedance element electrically connected to the resonance element. In the high-frequency filter device, which is connected to a receiver-side antenna, a signal monitoring section monitors unnecessary interfering signals of a received signal of a receiver of the wireless apparatus and generates a control signal for reception by an adaptive control algorithm, and a control section controls a band elimination filter by a control voltage signal based on the control signal so that an elimination band of the band elimination filter of the receiving filter maximizes a ratio of a desired received signal to interfering waves.

Abstract: The present invention quantifies and reduces losses in tunable bandpass filters having ferro-electric capacitors. Given a required insertion loss and the quality factor of a resonator, the geometric losses resulting from a particular topology for the ferro-electric capacitor and the metal losses are accounted for to quantify the allowable ferro-electric losses.

Abstract: A filter unit comprises a wideband bandpass filter; at least one band-elimination filter having a stop band within the passband of the bandpass filter, so that the passband is divided into a plurality of pass bands by the stop band; and the wideband bandpass filter and the band-elimination filter being disposed in a single dielectric member. Since the passband of a wideband bandpass filter is divided into a plurality of pass bands by stop bands of one or more band-elimination filters, signals having frequencies corresponding to these divided pass bands are able to pass through the filter unit simultaneously.

Abstract: A tunable ferroelectric component and a narrowband resonant circuit for measuring the loss of the ferroelectric component. The ferroelectric component may be a capacitor integrated in the resonant circuit. The testing method eliminates other sources of loss to isolate the loss due to the ferroelectric material and to demonstrate that this loss is low.

Abstract: This invention provides a notch filter including a main transmission line, a coupling mechanism, and at least one electrically tunable resonator coupled to the transmission line through the coupling mechanism. A tunable dielectric varactor or a microelectromechanical variable capacitor is provided in each of the resonators. Wireless telephone handsets that include the filter are also included.

Abstract: A filter has a plurality of resonators formed regularly on a substrate and made of a superconducting material. In measuring resonance frequency of the resonators, the filter and a conductive metal plate having an opening are placed in a vacuum chamber so that all the resonators other than one resonator which faces the opening are covered with the metal plate. The metal plate has an input probe and an output probe at the opening of the metal plate. The resonance frequency of each resonator is measured in sequence while rotating the metal plate. Each resonator is adjusted in shape by a laser trimming or providing a dielectric film in correspondence with the measured resonance frequency so that all the resonators have a fixed resonance frequency.

Abstract: A high quality-factor, tunable radio frequency or microwave resonator is disclosed. The resonator includes one or more microelectromechanical switches positioned along its length. The switches are comprised of metal membrane bridges spanning the microstrip resonator. The bridges are connected to radial stubs that comprise reactive loads. An electrostatic potential differential between the bridge and microstrip resonator causes the bridge to collapse, thereby coupling a radial stub to the microstrip. The imposition of the reactive loads on the resonator causes the resonant frequency to change. Multiple resonators employed in a filter configuration can be variably coupled using microelectromechanical bridges that engage or disengage capacitive air gaps between two microstrip lines, to control filter bandwidth over wide tuning ranges.

Abstract: A radio frequency electronic filter includes an input, an output, and first and second resonators coupled to the input and the output, with the first resonator including a first voltage tunable dielectric varactor and the second resonator including a second voltage tunable dielectric varactor. The resonators can include a lumped element resonator, a ceramic resonator, or a microstrip resonator. Additional voltage tunable dielectric varactors can be connected between the input and the first resonator and between the second resonator and the output. Voltage tunable dielectric varactors can also be connected between the first and second resonators.

Abstract: A multi-channel microwave switched filter bank, wherein the input circuitry and output circuitry are mounted on opposite sides of the filter bank, providing a compact structure with excellent isolation. The filter bank includes a set of microwave band pass filter circuits. A housing structure provides an outer conductive peripheral frame structure. A rack structure disposed within the housing structure has a plurality of elongated slots for mounting therein corresponding ones of the plurality of filter circuits. A top dielectric substrate board is mounted adjacent a first side of the rack structure and has a first set of openings formed therein for providing access to a first set of input/output (I/O) ports of the plurality of filter circuits. A bottom dielectric substrate board is mounted adjacent a second side of the rack structure opposite the first side and has a second set of openings formed therein for providing access to a second set of input/output (I/O) ports of the plurality of filter circuits.

Abstract: There is disclosed a first stub short bonded across conductive runners of a tuning stub at a distance preferably greater than a distance resulting in the desired frequency of operation of a voltage controlled oscillator tuned by the tuning stub. Thereafter, the voltage controlled oscillator is powered and tested to determine the frequency of operation of the voltage controlled oscillator. The position of a second stub short is determined based on the frequency of oscillation of the oscillator due to the presence of the first stub short, the geometry of the tuning stub and the desired frequency of operation of the voltage controlled oscillator. A second stub short is precisely positioned along the stub using automated equipment, relative to the position of the first stub short, to result in the desired frequency of operation of the voltage controlled oscillator.

Abstract: A high-frequency device comprises a dielectric substrate, a filter element which has a plurality of resonating elements made of a first superconductor film on the dielectric substrate, a dielectric plate which faces the dielectric substrate substantially in parallel with the substrate and covers the plurality of resonating elements, and a spacing adjusting member configured to control the spacing between the dielectric plate and the dielectric substrate. The high-frequency device enables the pass-band frequency of the filter to be adjusted with high accuracy without variations in the skirt characteristic or ripple characteristic.

Abstract: A variable bandpass filter system passes a selected range of frequencies while rejecting other frequencies in an RF input signal. The system includes a switch and an oscillator. The switch receives the RF input signal and an oscillating calibration signal, and passes the RF input signal or said oscillating calibration signal based on a control signal. The oscillator receives an output of the switch, and frequency and gain control signals. The frequency control signal selects an operating frequency of the oscillator, such that the operating frequency determines a range of frequencies to pass. The gain control signal selects gain of the oscillator, where the oscillating calibration signal allows the oscillator to be calibrated by varying the gain such that the oscillator acts as a filter.

Abstract: Modular thin film, distributed, lumped element band-pass filters. The filter circuitry is configured on a number of ceramic substrates. The component defining depositions are arranged to overlap and couple to one another with connecting vias. Alternative band-pass filter and delay line circuits are disclosed that provide desirable delay characteristics. Bordering ground conductors and covering ground planes shield lumped impedance resonator and overlapping capacitor elements and/or provide a hermetic seal between the layers. The assemblies are configured to accommodate a range of frequencies and permit pre-fabrication with subsequent laser trimming, assembly and packaging.

Abstract: Plural resonators formed on a dielectric substrate constitute a filter. The resonant frequency of each resonator is adjusted to a target frequency by accumulating dielectric material on the resonator. The degree of such adjustment is substantially proportional to the amount of the dielectric material. The resonators are originally designed to have a resonant frequency that is a little higher than the target frequency. The resonant frequency of each resonator deviates from the designed target because of various factors in manufacturing processes. Each resonant frequency is measured, its deviation from the target is calculated, and the amount of the dielectric material required to eliminate such deviation is determined before the adjustment process. Accordingly, the adjustment is easily performed without measuring the resonant frequency during the adjustment process.

Abstract: A method for easily adjusting the frequency of an attenuation pole in a dual-mode band pass filter which is very compact and greatly increases coupling strength while maintaining a great deal of freedom of design. The dual-mode band pass filter includes a metal film partially disposed on a main surface of a dielectric substrate or disposed inside of the dielectric resonator so as to define a resonator. An opening is formed in the metal film to couple two resonance modes. Input/output coupling circuits are coupled to the metal film. At least one of coupling portions of the input/output coupling circuits or input/output portions thereof are moved in a direction along a perimeter of the metal film.

Abstract: A laminated type dielectric filter including a first stage symmetric type strip line resonator and a last stage symmetric type strip line resonator each having at least two resonating elements arranged to oppose one another via dielectric layers, said resonators being aligned in a direction perpendicular to a stacking direction in which said resonating elements are stacked, an input electrode for coupling the first stage symmetric type strip line resonator to an input terminal, an output electrode for coupling the last stage symmetric type dielectric filter to an output terminal, an earth electrode substantially surrounding an outer surface of the laminated type dielectric filter, plural interlayer earth electrodes connected to the earth electrode, and one or more coupling electrode for coupling said plural symmetric type strip line resonators, said the resonating elements, input electrode, output electrode, interlayer earth electrodes and coupling electrodes are isolated by means of dielectric layers, and el

Abstract: The ring resonator of a high Q-factor has a planar conducting ring (1) that is dimensioned in regard to its conductor width (w) and its diameter (d) so that it resonates in an odd harmonic or overtone vibration mode but not in its fundamental mode.

Abstract: A dielectric filter includes a first dielectric layer containing at least a pair of strip-line resonators to be electromagnetically coupled to each other. Second and third dielectric layers are disposed in an opposed relation to each other with the first dielectric layer sandwiched therebetween and having substantially the same dielectric constant (K1). Each of the second and third dielectric layers contains at least one shield electrode. The dielectric filter further includes fourth and fifth dielectric layers which have substantially the same dielectric constant (K2) and are interposed between the first and second dielectric layers and between the first and third dielectric layers, respectively. The dielectric constant (K2) of the fourth and fifth dielectric layers is selected to be less than any one of the dielectric constant (K1) of the second and third dielectric layers and the dielectric constant (K3) of the first dielectric layer.

Abstract: A method and apparatus for the localized electrical fine tuning of passive multiple element microwave or RF devices in which a nonlinear dielectric material is deposited onto predetermined areas of a substrate containing the device. An appropriate electrically conductive material is deposited over predetermined areas of the nonlinear dielectric and the signal line of the device for providing electrical contact with the nonlinear dielectric. Individual, adjustable bias voltages are applied to the electrically conductive material allowing localized electrical fine tuning of the devices. The method of the present invention can be applied to manufactured devices, or can be incorporated into the design of the devices so that it is applied at the time the devices are manufactured. The invention can be configured to provide localized fine tuning for devices including but not limited to coplanar waveguides, slotline devices, stripline devices, and microstrip devices.

Abstract: A slot line band reject pass filter including a substrate of insulating material having slot line primary conductors formed thereon. One or more supplemental conductors are preferably coupled to the slot line primary conductors to achieve rejection of a desired frequency. Several embodiments of supplemental conductors are disclosed including substantially closed loop and non loop segments that extend in a range from parallel to perpendicular from the primary conductors. The supplemental conductors may be directly or electromagnetically coupled, or both.

Abstract: The resonator of the present invention is preferably made of low cost alumina offering performance in a variable frequency oscillator application that is nearly equivalent to that of a high Q dielectric design. The resonator structure is tunable over a wide range with substantially no effect on oscillator phase noise or signal amplitude. The resonator utilizes a unique geometric structure which employs a transmission line preferably on alumina, conducting via holes (called castellations) and a topside ground pattern formed with a thick film of silver and/or palladium. A plurality of resonators may be formed by a step and repeat pattern then snapped apart for low cost, high volume manufacture. The resonator may be tuned in both a vertical and horizontal direction by removing topside metal from the resonator, to raise and lower the frequency, until the desired frequency is met.

Abstract: The invention provides a filter, comprising: at least one inductance device, at least one resonator, and at least one switching device. The inductance device may be connected in parallel with said switching device, and the resonator may be connected in series with the switching device. The above filter is small in size that is capable of functioning for high-frequency signals of plural frequency bands which are relatively adjacent to each other.

Abstract: A voltage-controlled resonator is fabricated by laminating, one on top of the other, a first dielectric which has a resonant circuit and on the upper surface of which a variable-capacitance element is mounted, and a second dielectric which has a through-hole formed in a position thereof corresponding to the position of the variable-capacitance element and which has a dual function of shielding and resonant frequency tuning. With this structure, the height of the resonator can be further reduced compared with the prior art while retaining the shielding effect, and moreover, further precise resonant frequency tuning can be accomplished as compared with the prior art.

Abstract: The invention provides a band elimination filter, comprising: a ring shaped resonator adapted to resonate in two orthogonal modes combined together; one input-output terminal electrically connected to said ring shaped resonator; and a perturbation portion disposed in said ring shaped resonator. The perturbation portion may be composed of a portion of said ring shaped resonator at which a pattern width is different from the other portion of said ring shaped resonator. Or, the perturbation portion may be composed a lumped constant passive element.

Abstract: A voltage-controlled oscillator and a method capable of precisely adjusting a frequency shift amount are provided irrespective of a fluctuation in characteristics of elements such as a strip-line. A center tap 19 is formed in a strip-line 16 of a resonator. A switching element 20 is connected to the center tap 19, and this switching element 20 is turned ON, so that the center tap is shortcircuited to the ground so as to vary the oscillating frequency. A slit A1 is conducted in the vicinity of the center tap 19 along the strip-line 16 and directed toward a shortcircuited end 17 of the strip-line, so that a frequency shift amount is adjusted. Also, a slit B1 is conducted in the vicinity of the shortcircuited end 17 along the strip-line 16 and directed toward the center tap 19, so that a frequency shift amount is adjusted.

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: A dielectric laminated filter has a first dielectric laminated block including a first strip line electrode and a second dielectric laminated block including a second strip line electrode and a coupling element, wherein the first and the second dielectric laminated blocks are laminated via a first shield electrode and wherein the first and the second strip lines are connected via a third strip line. This configuration allows the unwanted electromagnetic coupling between a resonator and the coupling element to be neglected, and uses the third strip line electrode to form the first and the second strip line electrodes so that they extend across different layers, thereby enabling the size of the resonator to be reduced. In addition, since the third strip line electrode serves to adjust the filter characteristics, a small high-performance dielectric laminated filter that can be designed easily can be provided.

Abstract: An antenna device and a transmitting and receiving unit using the device which are capable of simultaneously polarizing each direction of a plurality of beams are provided without increasing the size of the whole device. For example, when the detection is achieved by forming a plurality of beams such as a radar of monopulse type, the angle measurement range is easily extended. A movable part is provided with a plurality of primary radiators and movable part side transmission lines (dielectric strips of NRD guide) to be coupled therewith, and a fixed part side is provided with dielectric lenses to form each focal plane at the position of primary radiators, and fixed part side transmission lines (dielectric strips of NRD guide) to be respectively coupled with the movable part side transmission lines. A plurality of beams are simultaneously tilted by displacing the movable part.

Abstract: Microwave hairpin-comb filters utilize a plurality of hairpin (i.e., folded) half-wavelength microstrip or stripline resonators arranged side-by-side and all with the same orientation. The coupling regions between resonators extend parallel to the sides of the resonators for substantially 1/8 to 1/4 wavelength at the frequency of resonance of the resonators. This length of coupling region between resonators, along with all resonators being oriented in the same direction, result in resonance effects in the coupling regions between the resonators. These effects greatly reduce the couplings between the resonators so that the resonators can be very closely spaced so as to produce a compact filter structure yet still have a narrow passband. The structure can also be made to produce poles of attenuation adjacent to the passband in order to enhance the filter cutoff characteristic.

Abstract: A modular thin film, distributed, lumped element band-pass filter. The filter circuitry is configured on a number of ceramic substrates. The component defining depositions are arranged to overlap and couple to one another with connecting vias. Alternative 800 MHz and 1.9 GHz band-pass filter circuits are disclosed. Bordering ground conductors and covering ground planes shield lumped impedance resonator and overlapping capacitor elements. The layers are configured to accommodate a range of frequencies and permit pre-fabrication with subsequent laser trimming, assembly and packaging.

Abstract: A dielectric filter (10) comprises two stripline resonators (20, 40) which are arranged on parallel planes, respectively, with dielectric layers (10d, 10e) being sandwiched therebetween and are electromagnetically coupled to each other. Each of the two stripline resonators (20, 40) comprises a first stripline portion grounded at a proximal end thereof and a second stripline portion extending from a distal end of the first stripline portion in the same direction as the first stripline portion extends. The width of the first stripline portion is slightly less than that of the second stripline portion. Side edges of the second stripline portion is shifted relative to respective side edges of the first stripline portion in the same direction which is perpendicular to the direction in which the first and second stripline portions extend. A generally rectangular notch extends in the second stripline portion from one side edge thereof.

Abstract: A narrow bandwidth (1 to >100 MHz) HTS microwave filter (30 or 50) is described which is tunable over a moderate frequency range (100 to >1000 MHz at X-band). The low loss (<1 dB) and GHz/microsecond tuning rates enable the filter to operate as a radar preselector filter. The filter consists of a multi-pole microstrip or stripline HTS coupled one-half resonator pattern deposited onto a ferrite substrate (32 or 52, 54). The ferrite substrate is operated in a latching mode like that in the operation of digital phase shifters. The filter tunability arises from the variation of the effective permeability with the remanent magnetization.

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: A variable bandwidth filter that includes either a parallel or series combination of a fixed impedance, such as a capacitor, and a variable impedance, such as a variable capacitor. The series and parallel combinations enable the ideal capacitance values for the filter coupling to be approximated thereby enabling a single control voltage to control the filter bandwidth without effecting the filter's upper frequency.

Abstract: An electrically tunable planar filter has a filter element including a substrate having an upper side and a wave-guide arranged on the upper side of the substrate, at least one tuning element composed of at least one material selected from the group consisting of a ferroelectric material and an antiferroelectric material with adjustable voltage applied to the tuning element and thereby with an adjustable dielectric constant, the tuning element being arranged at the upper side of the substrate.

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.