Abstract: The present disclosure has disclosed a base station antenna comprising an antenna core provided with an antenna base at the bottom thereof and provided with an antenna bracket at the top thereof; and a radome sleeved over the antenna core. The radome includes a top wall and a side wall that protrudes downward from the top wall. The antenna core and the radome are connected together by a fixed connection portion located near a bottom end of the radome and a floating connection portion located near a top end of the radome. The floating connection portion fixes a position of the radome on the antenna core in a horizontal direction and allows the radome to float relative to the antenna core in a vertical direction by cooperating the antenna bracket with the top wall of the radome or the side wall at the top of the radome.

Abstract: A new slide-screw impedance tuner structure uses multi-segment, disc-shaped, rotating metallic probes. This ensures probes covering multiple frequency bands to be served using a single vertical control mechanism, instead of multiple axes, motors, motor control and double or triple carriages. Additional benefits are high resolution in the area where the gap between center conductor and probe is small (high GAMMA), smooth increase of proximity between probe and center conductor (basic anti-corona discharge form) and the possibility to compensate for the negative phase slope at higher GAMMA, native to traditional slide screw tuners.

Abstract: A new slide-screw impedance tuner structure uses rotating metallic probes. This ensures high resolution in the area where the gap between center conductor and probe is small (high GAMMA), a smooth increase of proximity between probe and center conductor (basic anti-corona form) and the possibility to compensate for the negative phase slope at higher GAMMA, native to traditional slide screw tuners. Additionally the new structure simplifies the tuner mechanics by eliminating the need for a precise vertical axis.

Abstract: An electrical device that comprises a tunable cavity filter that includes a container and a post. The container encloses a cavity therein, wherein interior surfaces of the container are covered with a metal layer. The post is configured be movable through an opening in the container such that at least a portion of the post is locatable inside of the cavity.

Abstract: The adjustable resonator according to the invention has a casing, which is composed of walls, a lid and a bottom, a resonator cavity inside the casing and an internal conductor inside the resonator cavity, which internal conductor is in electric contact with the casing. The resonator further comprises a moveable adjustment piece, which comprises a conductive adjustment member, a conductive upper plate, and a dielectric support member. The adjustment member has a stem, which is vertical, and a cap as an expansion thereof. The adjustment member can be moved downwards so that its stem and the fixed internal conductor connected to the bottom of the resonator go within each other. The movement of the adjustment piece in the coaxial resonator first decreases the resonance frequency and then slowly increases it. Therefore the resonator provides a very wide adjustment area for the resonance frequency.

Abstract: A frequency tunable filter is disclosed. The frequency tunable filter includes a filter unit that can tune a frequency band of a frequency signal being filtered, a communication module that receives a control signal for controlling the tuning of the frequency band, and a control unit that controls the tuning of the frequency band based on the control signals. The disclosed filter can control the tuning of the filter's frequency band wirelessly.

Abstract: Tunable MEMS resonators having adjustable resonance frequency and capable of handling large signals are described. In one exemplary design, a tunable MEMS resonator includes (i) a first part having a cavity and a post and (ii) a second part mated to the first part and including a movable layer located under the post. Each part may be covered with a metal layer on the surface facing the other part. The movable plate may be mechanically moved by a DC voltage to vary the resonance frequency of the MEMS resonator. The cavity may have a rectangular or circular shape and may be empty or filled with a dielectric material. The post may be positioned in the middle of the cavity. The movable plate may be attached to the second part (i) via an anchor and operated as a cantilever or (ii) via two anchors and operated as a bridge.

Abstract: A high-order harmonic device of a cavity filter including a base and a lid cover the base is disclosed. The base has a through groove connecting to an upper and a lower portion. The base has a plurality of output terminal with metallic conductor extending into the inner side formed on the surface of the sidewall. The base has resonance space formed indented to receive the metallic conductor and extending to connect to the through groove. The lid has a plurality of threading holes formed corresponding to chambers and partitions received with adjusting elements for height adjustment. The adjusting elements has the resonance bars corresponding to every chamber and the suppressing bars corresponding to every partition. By adjusting suppressing bar and the partition to a predetermined distance, the space of the channel for transmitting the high-order harmonic wave can be reduced to suppress noise produced by high-order harmonic wave.

Abstract: A tunable filter for expanding tuning range includes: a housing, which has multiple cavities defined by partitions; a resonator contained in the cavity; at least one sliding member installed over the resonator; a main cover coupled to an upper portion of the housing; and at least one tuning element coupled to a lower portion of the sliding member and made of a metallic material. Tuning is accomplished by a sliding motion of the sliding member, and the resonator includes a cylindrical first conductor and a second conductor coupled to an upper portion of the cylindrical conductor, where a cross section of the second conductor is shaped as a circle with a portion removed such that an area of overlap between the tuning element and the second conductor is varied according to a sliding of the tuning element.

Abstract: The present invention is directed to a piezo-electrically actuated membrane (ex.—a tuner) configured for use with a tunable cavity filter. The piezo-electrically actuated tuner may be formed of printed circuit board materials and may be placed over the cavities of the tunable cavity filter. Further, the piezo-electrically actuated tuner may promote high level performance of the tunable cavity filter, while allowing the tunable cavity filter to be tunable across wide bands.

Abstract: Tunable MEMS resonators having adjustable resonance frequency and capable of handling large signals are described. In one exemplary design, a tunable MEMS resonator includes (i) a first part having a cavity and a post and (ii) a second part mated to the first part and including a movable plate located under the post. Each part may be covered with a metal layer on the surface facing the other part. The movable plate may be mechanically moved by a DC voltage to vary the resonance frequency of the MEMS resonator. The cavity may have a rectangular or circular shape and may be empty or filled with a dielectric material. The post may be positioned in the middle of the cavity. The movable plate may be attached to the second part (i) via an anchor and operated as a cantilever or (ii) via two anchors and operated as a bridge.

Abstract: The invention relates to a cavity filter comprising at least one tuning conductor (3) presenting a hollow portion (4), an isolation device (6) for a tuning conductor (3) of a cavity filter, and a node in a mobile communications network, comprising a cavity filter. According to the invention, the tuning conductor (3) comprises an isolation device (6) in a non-conductive material, which isolation device (6) is at least partly inserted into the hollow portion (4), and an insertion element (7) in a conductive material presenting a male thread (7a) that is engaged with an inner surface of the isolation device (6).

Abstract: A re-entrant resonant cavity 12 includes a first metallized molded plastic component 18, which comprises a re-entrant stub 17, an end wall 14 and a cylindrical side wall 13. The component 18 is surface mount soldered to a metallized PCB substrate 19. A rostrum 24 is located facing the end face 21 of the stub 17 to define a capacitive gap 22 with it. The end face 21 of the stub 17 and the rostrum 24 are configured such that relative rotation between them changes the profile of the gap 22 and hence the gap capacitance. By suitably locating the two parts during manufacture, a particular capacitance may be chosen to give a desired resonance frequency from a selection available depending on the relative angular position of the stub 17 and rostrum 24. In another cavity, the rostrum is replaced by an etched metallization layer of a printed circuit board.

Abstract: A resonator system is presented that has first and second cavity resonators for use in an RF amplifying system employing an RF amplifier device having an output circuit and an RF signal broadcasting antenna coupled to the output circuit. The resonators are interposed between the amplifying device output terminal and the antenna. The first resonator is comprised of a transmission line being a length of two coaxial conductors and tuned to the 3rd harmonic of the operating frequency (3fo). Each resonator has first and second opposing ends with the first end being an open end and the second end being a shorted end. The open end of the first resonator is connected to the output terminal of the RF amplifying device. The second resonator is connected in series with the first resonator and is tuned to the fundamental operating frequency (fo).

Abstract: A variable radio frequency band filter capable of varying the resonance frequency band comprises a housing having a support; a number of resonator rods arranged along the longitudinal direction of the housing; at least one tuning rod positioned on top of the resonator rods; a tuning support extending through the respective tuning rods along the longitudinal direction of the housing and adapted to slide on top of the respective resonator rods to vary the position of the tuning rods; and a frequency variation unit positioned on a lateral surface of the housing. The frequency variation unit being coupled to an end of the tuning support and adapted to vary the position of the tuning rods, as the tuning support is slid, according to the frequency band.

Abstract: A resonator system is presented that has first and second cavity resonators for use in an RF amplifying system employing an RF amplifier device having an output circuit and an RF signal broadcasting antenna coupled to the output circuit. The resonators are interposed between the amplifying device output terminal and the antenna. The first resonator is comprised of a transmission line being a length of two coaxial conductors and tuned to the 3rd harmonic of the operating frequency (3fo). Each resonator has first and second opposing ends with the first end being an open end and the second end being a shorted end. The open end of the first resonator is connected to the output terminal of the RF amplifying device. The second resonator is connected in series with the first resonator and is tuned to the fundamental operating frequency (fo).

Abstract: The invention concerns a coaxial automatic impedance adaptor characterized in that it comprises two slugs and has only a lateral translational movement along an axis Ox. The double slug tuner principle is based on the movement of two line segments of different characteristics of 50 O inside a closed cylinder on either side of standard connectors.

Abstract: A variable radio frequency band filter capable of varying the resonance frequency band comprises a housing having a support; a number of resonator rods arranged along the longitudinal direction of the housing; at least one tuning rod positioned on top of the resonator rods; a tuning support extending through the respective tuning rods along the longitudinal direction of the housing and adapted to slide on top of the respective resonator rods to vary the position of the tuning rods; and a frequency variation unit positioned on a lateral surface of the housing. The frequency variation unit being coupled to an end of the tuning support and adapted to vary the position of the tuning rods, as the tuning support is slid, according to the frequency band.

Abstract: The present invention relates to an improved tuning arrangement to linearise the sensitivity to frequency changes within a certain frequency range in response to tuner displacements relative to a resonator body. The tuning arrangement comprises a tuner and/or resonator having a non-uniform distribution of the effective dielectric permittivity along the axis of tuner displacement. The non-uniform distribution of the effective dielectric permittivity is realised by subdividing the tuner into an arbitrary number of sections, each of which distinguishable at least by their geometrical shape and the value and distribution of the dielectric coefficient ?r.

Abstract: A high Q RF cavity resonator loaded with a ceramic disc, the resonator comprising an inner conductive post having a length less than a quarter wavelength. The resonance frequency of the resonator is tunable by changing a distance between a) an outer plate and b) a ceramic disc and an end cap where the ceramic disc is located between the outer plate and the end cap. The resonance frequency can be tuned when the outer plate, ceramic disc, and end cap are in contact with each other by varying a pressure between the contact surfaces of the ceramic disc, the end cap and the outer plate. Temperature compensation allows the resonator to hold a resonance frequency despite changes in temperature, and can be achieved by selecting thermal coefficients of expansion of components holding or placing the ceramic disc and end cap relative to the outer plate.

Abstract: A variable radio frequency band filter capable of varying the resonance frequency band comprises a housing having a support; a number of resonator rods arranged along the longitudinal direction of the housing; at least one tuning rod positioned on top of the resonator rods; a tuning support extending through the respective tuning rods along the longitudinal direction of the housing and adapted to slide on top of the respective resonator rods to vary the position of the tuning rods; and a frequency variation unit positioned on a lateral surface of the housing. The frequency variation unit being coupled to an end of the tuning support and adapted to vary the position of the tuning rods, as the tuning support is slid, according to the frequency band.

Abstract: A microstrip-based RF coil for use in an MRI apparatus constructed to perform human head imaging is provided and includes (a) a cylindrical non-magnetic core module having an outer surface and a longitudinal axis, a cylindrical bore extending through the core module along the longitudinal axis and defining an inner surface; and a plurality of conductive strip lines. The strip lines extend parallel to the longitudinal axis on the outer surface of the core module. The coil is constructed such that one or more of the conductive strips are divided into conductive microstrip segments with one or more tuning capacitors being bridged between two adjacent microstrip segmented sections of the conductive strip. The coil also include a shield support cylinder that is disposed concentrically about the core module and is spaced therefrom to receive the tuning capacitors.

Abstract: A tunable RF cavity resonator having reduced generation of passive inter-modulation, the tunable RF cavity resonator including a cavity body, a fixed tuning post at a first end of the cavity body, a dielectric rod in the fixed tuning post interior space with a first spatial gap between the dielectric rod outer surface and the fixed tuning post inner wall, a tuning screw connected to a first end of the dielectric rod, and a tuning element disposed on a second end of the dielectric rod so that the tuning element moves within the interior space of the fixed tuning post while maintaining a second spatial gap between the tuning element outer surface and the fixed tuning post inner wall. Accordingly, the tuning element forms a short section of very low RF impedance transmission line thereby preventing RF signal leakage through the interior space of the fixed tuning post.

Abstract: Disclosed is a method and apparatus for tuning a microwave apparatus. The chamber volume of the microwave apparatus can be changed by moving a flexible portion of a flexible wall while a perimeter portion of the flexible wall remains fixed.

Abstract: The present invention relates to a fastener means for securing a center conductor (23) in a cavity filter and for enabling the center conductor to be secured mechanically in a stable fashion and with good electric contact between itself and the bottom 22 of the cavity. The inventive fastener means comprises a center conductor and a fastener element (25, 26) provided integral therewith to form a single-piece structure, which structure may have the form of a screw with the center conductor (23) as the screw head at one end and screw threads (26) at the other end. The contact surface between the fastener means and the cavity bottom is surface-treated with a material of low resistivity, such as silver for example.

Abstract: A tunable resonant cavity including a cavity housing having top and bottom walls with a post disposed in said cavity extending from die bottom of the cavity toward and spaced from the top. The length of the post is adjustable to adjust the resonant frequency of the cavity. The materials forming the resonant cavity are selected to provide temperature compensation.

Abstract: The present invention relates to an arrangement in a cavity filter for tuning the frequency relationship of the filter or its coupling coefficient factor. The arrangement includes a self-locking screw that can be fitted in the filter cavity, for instance in the center conductor, in the filter lid, or in some suitable place in the filter chassis. Tuning is effected by adjusting the position of the screw in relation to the center conductor or lid of the cavity filter. The screw can be made of metallic segments embedded in plastic, or made completely of metal, and provided with a radially through-penetrating slot. At least one part of the screw has a cross-sectional area whose extension perpendicular to the through-penetrating slot is slightly greater than in a direction along said slot.

Abstract: In a sleeve in a radio frequency filter at least one portion having a lateral dimension being smaller than the diameter of a screw to be threaded through the sleeve is provided. The portion is flexible in a radial direction, so that a screw threaded through the sleeve will be secured by a clamping force. The increased friction provided by this clamping force will hold the screw in a locked position. The magnitude of the clamping force can be varied within broad ranges, and the optimum force will be different for different applications. Thus, by using such a screw and sleeve, there is no need for a lock nut and the screw does not need to be readjusted once placed in the correct position.

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: 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: 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 resonator consists of an external conductor (1), a dielectric plate (2), a resonance capacity element, an input terminal (5), and an output terminal (6). The dielectric plate (2) is fixed at its upper and lower ends to the upper and lower walls, respectively, of the external conductor (1). The resonance capacity element is composed of electrodes of a metal thin layer or a metal plate provided on the front and back of the dielectric plate (2). The lower end of one of the electrodes is electrically connected to the lower wall of the external conductor (1), and a gap is formed between the upper end of the electrode and the upper wall of the external conductor (1), while the upper end of the other electrode is electrically connected to the upper wall of the external conductor (1), and a gap is formed between the lower end of the other electrode and the lower wall of the external conductor (1).

Abstract: A temperature-compensated combiner including a control rod disposed in a combiner housing for controlling a middle frequency; a resonator tube secured to the housing and coaxially disposed around the control rod; a regulating cup arranged at an end of the control rod which faces the housing; a motor which controls the middle frequency and which is arranged at one end of the control rod; and a temperature-compensating tube for compensating for longitudinal changes exhibited by a unit including the control rod, the resonator tube and the regulating cup for changes in temperature. The temperature-compensating tube is positioned within the resonator tube and secured to that end of the resonator tube which faces the housing and to the frame of the motor.

Abstract: A mechanically tunable ceramic bandpass filter incorporates at least one resonator, the resonator including a resonator body, a coupling capacitor electrically connected to the resonator body, and an electrode pin electrically connected to the coupling capacitor and electrically isolated from the resonator body. A holding bracket fixedly supports the resonator, and is electrically connected to the resonator body. A mechanically deformable tuning tab is fixedly supported and electrically connected to the bracket at a first end. A second end of the tuning tab, variably positioned with the resonator body, forms a variable capacitor for tuning a resonant frequency of the resonator.

Abstract: The invention relates to a coaxial resonator comprising an inner conductor (12) with walls defining therebetween a free space (24), and a housing portion (13) surrounding the inner conductor (12) and forming an outer conductor of the resonator. In order that connection to the inner conductor could be made very simply, the inner conductor (12) is made of sheet material in which slits (21; 33) extending in the direction of the inner conductor are made so that they form between them a tongue-like connecting part (22; 34) having its free end connected to a printed circuit board (11).

Abstract: The invention relates to a dielectric resonator comprising a block (2) of dielectric material, having upper (9), lower and side surfaces and in which there is a hole (3a) extending from the upper surface to the lower surface. The hole (3a) and the lower surface as well as at least part of the side surfaces are coated with an electrically conductive material and at least the upper surface (9) is uncoated so that the hole (3a) thus forms a transmission line resonator. The uncoated surfaces are covered with a lid (5) of an electrically conductive material, whereby the dielectric block is substantially surrounded by an electrically conductive material. The resonator hole (3a) is composed of two portions, a straight portion (3a) beginning from the lower surface of the dielectric block as well as a wider portion (10) that is formed above the straight portion and opens into the upper surface (9) of the dielectric block.

Abstract: In a combiner filter for a cellular telephone system, there is a coaxial resonator which includes a rectangular cavity. Within the rectangular cavity, there is a central conductor having an oval shaped plate. The central conductor and oval shaped plate are displaced within the rectangular cavity to establish the fundamental resonator frequency. Adjacent to the central conductor plate is a rotatable I-beam shaped element which is preferably rotated by a shaft coupled to a stepper motor. The rotation of the I-beam shaped element provides frequency adjustment or tuning for the coaxial resonator.

Abstract: A dielectric TEM resonator, whose resonant frequency is adjustable in both directions after being incorporated in a circuit, is disclosed. A first dielectric TEM resonator comprises a metal member disposed near an open end of a resonator body and coupled to an inner or outer conductor of the resonator body. The resonant frequency is adjusted by adjusting a distance between the open end and the metal member. A dielectric material of a second dielectric TEM resonator is partially exposed, and a dielectric board for mounting the resonator body is also exposed in a corresponding part to the exposed part of the dielectric material. The exposed part of the dielectric board is partially covered with a metal plate. The resonant frequency is adjusted by adjusting the covered area.

Abstract: The invention relates to a stripline circuit comprising at least one stripline pattern (2 to 6) made of a material of high electrical conductivity on the surface of a printed board (1) made of a dielectric material, a metallic or metal coated cover (8 to 12) being provided in the vicinity of the stripline pattern in an electrically non-conducting manner with respect to it, and the distance of the cover (8 to 12) from the stripline pattern being adjustable to regulate the characteristic impedance of the stripline. In order to simplify practical circuit solutions, each cover (8 to 12) is integral with a casing (7) protecting the printed board (1).

Abstract: The invention relates to a stripline circuit comprising a stripline structure of a high-conductive material disposed on the surface of a board of a dielectric material, as well as a method for regulating such a stripline circuit. The invention is characterized in that a metallic or metal coated cover (4) is non-conductively provided in the vicinity of the stripline structure (2), the distance of the cover from the stripline being adjustable to regulate the characteristic impedance of the stripline. The distance of the cover from the stripline is preferably adjusted by bending the cover (4).

Abstract: A tunable resonant cavity filter structure is disclosed which includes an enhanced ground return internal to the cavity which effectively eliminates generation of deterioration wide band noise and optimizes unloaded Q as well as rending resonant frequency stable with vibration. In its preferred form, the enhanced ground return is in the form of a ground return clip with reliant radial projections that mate with the threads of the threadable tuning element used to determine final operating frequency. The radial projections are deflected in cantilever fashion so as to generate sufficient pressure to break thru any oxides in the tuning element threads and ensure metal-to-metal contact.

Abstract: The disclosure is directed to a dielectric material coaxial resonator provided with an improved resonance frequency adjusting mechanism which is arranged to eliminate deviations of the resonance frequency after adjustment for adjusting the resonance frequency.

Abstract: A microwave oscillator of the type in which a dielectric resonator is disposed inside a conductive housing, characterized in that a conductive rod-like member is disposed inside the housing and arranged in parallel with the axis of the dielectric resonator with one end connected electrically to the housing and the other end left free. Preferrably, the rod-like member is made so thin as to interrupt little the magnetic flux generated by the dielectric resonator, and the resonance frequency of the housing is selected lower than that of the dielectric resonator.

Abstract: The invention relates to a device for the fine adjustment of a resonant microstrip-line formed on an insulating substrate (2), tuned by a varicap diode (7,8) which makes it possible to adjust the shape of the curve representing the tuning frequency of the strip line as a function of the direct voltage controlling the diode. One or more blind holes are provided in the surface of the substrate opposite the strip line, and a base part (15) with one or more threaded holes, into which cylinders are screwed, is fitted under the strip line. The cylinders are placed facing the blind holes and are aligned with the holes to enable entry into them. The cylinders and the base part are electrically conductive and connected to ground.

Abstract: Transmitter combining apparatus includes up to five RF filters (100) coupled to a microstrip combiner (300) for combining up to five input signals for application to a common antenna. The RF filter (100) includes a ceramic resonator (116) sandwiched between first and second compensating discs (114 and 120) and first and second shield plates (142 and 148) for temperature compensation, low loss mounting and heat sinking of the ceramic resonator (116). Good thermal contact between the ceramic resonator (116), discs (114 and 120) and shield plates (142 and 148) is produced by a compressive force exerted by springs (144-147) of shield plate (142) when the top cover (112) is attached to the aluminum housing (124). The resonant frequency of the RF filter is tuned by means of an aluminum tuning shaft (102) and ceramic tuning core (118) which are positioned by brass bushing (133) in top cover (112).

Abstract: A coaxial dielectric resonator for VHF and/or UHF band comprising a generally cylindrical dielectric having inner surface and outer surface. The inner and outer surfaces of the dielectric are respectively covered by outer and inner conductors and these conductors are connected at one end of the dielectric. An adjusting screw for adjusting resonance frequency is provided at the other end of the dielectric which is covered by a lid while holding a gap between the adjusting screw and the lid. A microwave filter using a plurality of the coaxial dielectric resonator is further described.

Abstract: A strip-line resonator comprises a first dielectric substrate having a conductive film on one surface thereof for connection to ground and a strip line on the other surface thereof and a second dielectric substrate having one surface thereof making contact with the strip line and a conductive film on the other surface thereof for connection to ground. Fused glass having a low melting point for is applied between the first and second substrates to bond them together. A portion of open-circuit end of the strip line is exposed and formed with slits or gap to facilitate frequency adjustment.

Abstract: The microwave resonator includes an enclosed resonator housing and a hollow central conductor having one end fastened to a bottom of the resonator housing and extending toward a top wall of the resonator housing. The other end of the central conductors is spaced from the top wall and includes an adjustable bellows assembly disposed coaxial of a longitudinal axis of the central conductor. A non-rotating, axially movable drive shaft is disposed coaxial of the axis of the central conductor within the central conductor. One end of the drive shaft is fastened to the bellows assembly and the other end of the drive shaft is coupled to a drive means disposed in the bottom wall to cause axial movement of the drive shaft to adjust the axial length of the bellows assembly and, hence, the axial length of the central conductor to adjust the resonant frequency of the microwave resonator.

Abstract: The method according to the invention comprises winding a metal wire substantially helically both round a fitting constituted by a flexible strip and around two rods arranged parallel to the fitting axis and on either side of the fitting. The rods are eliminated when the metal wire is wound. The fitting comprises means limiting the displacement of the wire in accordance with the fitting axis, which coincides with the axis of the helix according to which the wire is found. These means are constituted by two rows of slots made in the lengthwise direction on two opposite edges of the strip constituting the fitting.

Abstract: A semi-coaxial cavity resonator filter including a plurality of semi-axial cavity resonators, as constructed units, each of which has an adjustable device in which dielectric substrates having a specific dielectric constant of more than 1 are disposed in the gap between the inside wall of a tube-shaped outer conductor and the open end of an inner conductor provided on the inside wall of the outer conductor, and the electrostatic capacitance of the spaces interposed by the dielectric substrates is changed without steps by varying the area of the electrodes on the dielectric substrate. The filter is made by making an individual and predetermined frequency adjustment on the plurality of the semi-axial cavity resonators and then cascade-connecting those resonators in one block through shielding plates having a coupling iris so as to obtain desired filtering characteristics as a bandpass filter.