61 results about "Degenerate mode" patented technology

Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

The invention relates to a microstrip dual-mode filter of nesting ring-structured parallel feeder lines, comprising a front part metal microstrip line, a back part metal coating, an interlayer dielectric slab and an input / output port. Structure of the metal microstrip line consists of a multiplex nesting ring-structured dual-mode resonator, an input feeder line and an output feeder line of which are arranged on the same horizontal line; the input feeder line and the output feeder line are gap-coupled with an internal resonator by a pair of U-shaped coupling arms; and a perturbation which is formed by the linewidth difference Delta m between an inter loop line and an outer loop line and the small patch on a perpendicular symmetric line controls degenerate mode and adjusts two output zero positions. Compared with the traditional microstrip dual-mode filter of parallel feeder lines, the invention has the advantages of less size and better frequency selectivity, and can flexibly adjust the output performance curve zero position of the filter. The invention can be used for designing a narrowband band-pass filter of a wireless communication system and be applicable for filter miniaturization requirement of the wireless communication system.

Bulk acoustic wave (BAW) gyroscopes purposefully operate using non-degenerate modes, i.e., resonant frequencies of drive and sense modes are controlled so they are not identical. The resonant frequencies differ by a small controlled amount (Δf). The difference (Δf) is selected such that the loss of sensitivity, as a result of using non-degenerate modes, is modest. Non-degenerate operation can yield better bandwidth and improves signal-to-noise ratio (SNR) over comparable degenerate mode operation. Increasing Q of a BAW resonator facilitates trading bandwidth for increased SNR, thereby providing a combination of bandwidth and SNR that is better than that achievable from degenerate mode devices. In addition, a split electrode configuration facilitates minimizing quadrature errors in BAW resonators.

The invention discloses a large K-waveband conformal antenna array plane and aims to provide a conformal phased array antenna array plane which does not generate a frequency deviation or a relatively high derotation component, and has a good broadband wide-angle scanning gain characteristics and good broadband wide-angle scanning circular polarization characteristics. The large K-waveband conformal antenna array plane is realized through the following technical scheme: conductor patches are divided into four groups and are arranged on an upper surface of a lower dielectric substrate in a form of a quadrant sequence rotation array, and projections of feeding points of a micro-strip patch antenna on a plane plate are arranged triangularly; the conductor patches are sandwiched between an upper dielectric substrate and the lower dielectric substrate; a radio frequency coaxial connector sequentially passes through the plane plate, a metal cone and the lower dielectric substrate to jointly form the micro-strip patch antenna; the radio frequency coaxial connector carries out coaxial probe feeding on the micro-strip patch antenna; and a pair of orthogonal polarization degenerate modes which have equal amplitudes and a phase difference of 90 degrees are excited on the conductor patches to form the conformal phased array antenna array plane for radiating right-handed circular polarization electromagnetic waves.

A magnet-free non-reciprocal device realized using modulated filters. The device includes one or more filters in one or more branches, where each branch connects two ports or a port and a central node. The poles and zeros of each of the first, second and third filters are modulated in time such that degenerate modes at each pole and zero is split thereby destructively interfering at one or more output ports and adding up at another output port allowing non-reciprocal transmission, isolation and / or non-reciprocal phase shift. The device is able to realize a magnet-free full-duplex communication scheme implementing a magnet-free circulator for radio frequency cancellation or a magnet-free isolator or gyrator.

The invention discloses a watch antenna device and an electronic watch. The watch antenna device comprises a metal frame, a PCB and a mode separating circuit, wherein the PCB is provided with a metal layer and gaps for gap radiation between the PCB and the metal frame. The mode separating circuit is used for a radiation mode for exciting a radiation signal between the metal frame and the PCB and a degenerate mode circuit thereof and furthermore is connected between a signal input for feeding a signal to the metal frame and feeding points on the metal frame. Compared with the prior art, the watch antenna device provided by an embodiment of the invention can expand spectral bandwidth. The watch antenna device can be used as the antenna device of the intelligent watch.

The present invention relates to a kind of tunable plasma resonant cavity for PCVD optical fiber perform rod processing machine. The tunable plasma resonant cavity includes cylindrical resonant cavity casing and cut-off waveguides set on two ends of the casing, and features the tuning piston, which is set on one end of the cylindrical resonant cavity and has middle part with through hole and back end stretched beyond the casing. Setting the tuning piston can realize the matching between the waveguide device and the resonant cavity and the real-time control of energy coupling, raise the processing precision and efficiency of PCVD process, avoid the damage of microwave on the system devices and increase the service life of the plasma resonant cavity microwave system. The present invention has stable field structure, no polarizing and degenerate mode, low loss and high Q and other features.

The invention discloses a circularly polarized slot antenna based on a triangular substrate integrated waveguide resonant cavity. Two vertical rectangular radiation slots are etched at the central area of the upper metal surface of the equilaterally triangular resonant cavity, and the grounded coplanar waveguide on the lower metal surface of a dielectric plate is enabled to perform feeding so that the antenna is enabled to work in a TE<120> mode and a TE<210> mode in turn. Splitting of two degenerate modes in the resonant cavity is caused by adjusting the length difference of two radiation slots on the cavity so that the linearly polarized electromagnetic waves radiated by the two radiation slots are enabled to realize equal amplitude in a certain frequency band with the phase difference of 90 degrees, and thus the circularly polarized waves can be formed in the far field through superposition. According to the antenna structure, the advantage of high radiation performance of the conventional metal back cavity slot antenna is reserved and the profile is quite low. Besides, the whole antenna, including the radiation slots, the feed structure and the back cavity, is completely manufactured on the single layer dielectric plate so that the processing complexity can be greatly reduced, the processing cost can be reduced and planar circuit integration is enabled to be easier.

The invention discloses a broadband filter adopting a one-cavity triple-mode cavity resonator. The broadband filter comprises a cavity, a first port, a second port and a perturbation metal body, wherein the perturbation metal body is arranged at the bottom of the cavity, the center of the perturbation metal body deviates from the center of the cavity, and the first port and the second port are arranged on the cavity and penetrate through the outer wall and the inner wall of the cavity. A first conductor assembly is arranged at the first port, a second conductor assembly is arranged at the second port, the axis of the first conductor assembly and the axis of the second conductor assembly are perpendicular to each other and perpendicular to the longitudinal center line of the cavity respectively. A degenerate mode is separated by the method of skewing of the resonator, and therefore, the broadband filter has the advantages of high selectiveness and Q value and simple design, has a wider fractional bandwidth, can meet requirements of miniaturization communication, is easy to manufacture without machining any chamfers or performing slotting, solves the problem of complexity of band wide and narrow machining of the existing cavity filter, and is simple in structure and wide in application range.

The invention relates to a double-passband difference filter based on micro double-mode medium resonators. The filter comprises a metal chamber, two double-mode medium resonators and two sets of difference excitation structures, wherein the middle position of the metal chamber is provided with a metal baffle board used for segmenting the metal chamber into two rectangular chambers, each rectangular chamber is internally provided with one double-mode medium resonator and one set of difference excitation structures arranged at two opposite sides of the double-mode medium resonator, the double-mode medium resonator is a rectangular medium resonator of which the cross section is a square structure, the bottom portion of the double-mode medium resonator directly contacts with a bottom portion of the metal chamber, the diagonal position of the double-mode medium resonator is provided with a pair of tangent angles used for separating an orthogonal degeneration mode, the diagonal line of the pair of tangent angles of each double-mode medium resonator is parallel with the metal baffle board, and projections of the two sets of difference excitation structures on the bottom portion of the metal chamber are four vertexes of a parallelogram. The filter has advantages of small volume, low insertion loss, high passband selectivity and high inter-passband isolation.

The invention discloses a circularly polarized slot antenna with filtering characteristic. The circularly polarized slot antenna comprises a dielectric substrate, metal ground, a microstrip structure and a distributed capacitor; the metal ground is arranged on the upper surface of the dielectric substrate; the microstrip structure is arranged on the lower surface of the dielectric substrate; a circular annular radiation slot is formed in the middle of the metal ground; the metal ground is divided into inner side metal and outer side metal by the circular annular radiation slot; the distributed capacitor crosses over the inner side metal and the outer side metal on the two sides of the circular annular radiation slot; the microstrip structure comprises an input microstrip line, a microstrip coupling line filter, an output microstrip line and a circular tuning patch which are connected in sequence; the microstrip structure couples an input signal to the circular annular radiation slot; and the main mode of the circular annular radiation slot is split into two orthogonal degenerate modes by infinitesimal disturbance of the distributed capacitor to further obtain the filtering and circular polarization radiation characteristics. The circularly polarized slot antenna with the filtering characteristic has high bandwidth, high filtering characteristic, compact structure, convenience in manufacturing and low cost, and can be used for the modern wireless communication terminal.

The invention relates to an integrated substrate wave-guide bandpass filter based on a triangular complementary split-ring resonator. The integrated substrate wave-guide bandpass filter comprises a resonant cavity in equilateral triangle, the resonant cavity is composed of an upper surface metal layer, a medium substrate and a lower surface metal grounding plate stacked in order; the upper metal layer is communicated with the lower surface metal grounding plate through the bottom metal column after penetrating the medium substrate; and a triangular complementary split-ring resonator is arranged at a center location of the upper surface metal layer, wherein the triangular complementary split-ring resonator is loaded in a pair of triangular resonant cavities in a degenerate mode, the complementary split-ring resonant can product a passband, the produced passband is modulated to a pair of degenerate modes by regulating the parameter of the ring resonator, thereby improving the bandwidth of the filter. The transmission zero point of the bandpass filter can be further adjusted by opening a round interference metal hole in the resonant cavity, thereby effectively inhibiting the out-of-band harmonic. The bandpass filter disclosed by the invention is not only simple in structure, convenient for processing, but also can effectively inhibit the out-of-band harmonic since the transmissionzero-points are coexistent in the low-frequency end and the high-frequency end, the high frequency selectivity and excellent performance are provided.

The invention belongs to the technical field of filters, and discloses a dual-mode SIW filter capable of realizing frequency and bandwidth and zero-point adjustability. The dual-mode SIW filter is composed of an upper metal surface, an intermediate medium substrate and a lower metal bottom surface, and is composed of a square substrate integrated waveguide dual-mode resonant cavity; and frequencyadjustability, bandwidth reconfigurability and zero point controllability of the filter are realized by utilizing the simple-parallel mode of the square cavity; the overlarge size caused by direct coupling cascade connection of multiple cavities can be avoided; the problem that the insertion loss is relatively high is solved, and the size of the whole filter is relatively compacted; two transmission zero points are introduced to the two sides of the filter passband, so that the selectivity and out-of-band rejection of the filter are improved; the frequency adjustability is realized in a wide frequency band, and the bandwidth reconfigurability and zero point controllability are realized, so that the functions can be realized only in a single cavity by changing the different capacitance values of five variable capacitance diodes.

The present invention discloses a coplanar waveguide fed broadband circularly polarized antenna. The antenna comprises a circular dielectric substrate, the bottom part of the circular dielectric substrate is cut off along a flat tangent, a circular groove with the same circle center as the circular dielectric substrate is formed in the middle part of the circular dielectric substrate, a notch is formed along a direction perpendicular to the flat tangent at the edge of the bottom part of the circular groove, a vertical strap stretching into the circular groove is disposed in the notch, one end of the vertical strap on the flat tangent is a rectangular piece while the other end is a round piece, access entries are formed at centers of two side faces of the circular groove, one side face is connected through the access entry with a horizontal strap stretching into the circular groove, and one end of the horizontal strap inside the circular groove is a round metal piece. The horizontal strap is connected on the side face of the circular groove and thus forms an orthogonal degenerate mode with a 90-degree phase difference with the vertical strap, thereby realizing the circular polarization feature; and the horizontal strap are connected to the access entries at the two sides of the circular groove, such that switching between left-handed circular polarization and right-handed circular polarization can be conveniently realized.

The invention discloses an integrated substrate waveguide three-passband filter based on a complementary open resonant ring. The integrated substrate waveguide three-passband filter comprises a triangular resonant cavity, wherein the triangular resonant cavity comprises a top metal layer, a dielectric substrate and a bottom metal layer which are arranged in parallel from top to bottom in order; three rows of metal pillar through holes parallel to three sides are formed in the dielectric substrate; a microstrip transmission line is extended from the middle position between the midpoints of twosides and the top point of the top metal layer respectively; and a complementary open resonant ring structure is arranged at the central position of the top metal layer; through the connection position of the microstrip line and the relevant parameters of the resonant ring, the equivalent resonant frequency of the resonant ring is adjusted between the main mode and the degenerate mode, so as to realize the filter three-pass band performance; the transmission zero point is generated on each of two sides of each passband sides of each pass band, so that out-of-band harmonics can be suppressed effectively and the frequency selectivity is high; and on the basis of single cavity, the filtering effect of three-passband can be realized, and integrated substrate waveguide three-passband filter based on a complementary open resonant ring meets the requirement for miniaturization and high performance of modern wireless communication.

The invention relates to a Ka frequency range miniaturization broadband multimode auto-tracking feed source network. Two polarization degenerate modes of TE21 mode transmitted by center circular waveguide are coupled to four rectangular waveguide by adopting a four-arm circular polarization TE21 coupler. Two four-way polarization degenerate modes of the TE21 mode is combined into two two-way polarization degenerate modes of the TE21 mode by two broadband magic Ts. A left-handed or right-handed circular polarization difference mode is output by a broadband 90-degree electrical bridge. The TE21 coupler center circular waveguide is capable of simultaneously transmitting a TE11 mode. Due to the fact that the TE21 coupler is connected with a broadband circular polarization machine, and two polarization modes of a signal are respectively output from two ports of the broadband circular polarization machine, the Ka frequency range miniaturization broadband multimode auto-tracking feed source network is capable of simultaneously receiving a signal of double-circular polarization and a difference signal, and thereby the auto-tracking function is realized. The Ka frequency range miniaturization broadband multimode auto-tracking feed source network has the advantages of not only simplifying composition of the feed source network, reducing the volume and the weight of the whole device, but also reducing network construction, saving feed source cost and broadening working band of the feed source network.

The invention provides an MEMS sensor and a starting circuit. The starting circuit is used for starting a band-gap reference core circuit and comprises an equivalent resistance generation unit and a state switching unit, wherein the equivalent resistance generation unit is composed of an equivalent transistor M1, and the equivalent transistor M1 comprises a plurality of equivalent field effect transistors connected in series; the state switching unit is electrically connected with the equivalent resistance unit and the band-gap reference core circuit; and the state switching unit is used for pulling up an internal node of the reference core circuit to force the internal node to be separated from a degenerate mode when detecting that the output voltage of the band-gap reference core circuitis 0, so that the band-gap reference core circuit can enter a normal working mode. According to the starting circuit, the equivalent transistor M1 is used for replacing a traditional resistor, so that the area of a chip can be smaller, and integration is facilitated, and when the band-gap reference core circuit is in a normal working mode, quiescent current is not consumed on the starting circuit, and the requirement for low power consumption is met.

The invention discloses a substrate integrated waveguide filter coupler based on an orthogonal degenerate mode, which comprises three resonant cavities, four feeder lines and four ports. The functionsof the integrated band-pass filter and the ring coupler are integrated, the cascade connection of two traditional filters and one ring coupler can be replaced in terms of function, and the volume isgreatly reduced. The zero-degree and 180-degree phase difference between the two output ports of the filter coupler is realized by using the forward and reverse electric fields of the quadrature degenerate modes of the substrate integrated waveguides TE102 and TE201. No additional circuits are needed to reduce the circuit complexity. The substrate integrated waveguide filter coupler provided by the invention has good circuit performance and the characteristic of high integration.

The invention discloses a magnetic-adjustable dual-mode bandpass filter, and belongs to the field of microwaves and millimeter waves. The filter comprises a dielectric substrate and two metal layers,wherein the two metal layers are arranged on an upper surface and a lower surface of the dielectric substrate, the two metal layers are connected by a metal through hole array, the dielectric substrate, the two metal layers and the metal through hole array form a dual-mode resonant cavity, four through holes are formed in the dual-mode resonant cavity and are in close contact with parts around themetal through hole array, and ferrites are arranged in the through holes. With the adoption of the dual-mode resonant cavity, the circuit area of the filter is reduced, and the magnetic-adjustable dual-mode bandpass filter has the advantages of low insertion loss, good selectivity, good harmonic suppression and the like; with the application of the ferrites, the resonant frequency of the dual-mode resonant cavity is changed, and the coupling strength between two degenerate modes also can be controlled; and the working frequency of the filter moves towards a high-frequency direction with the increase of the intensity of an external bias magnetic field, the dynamic adjustable range is wide, and the bandwidth flexibility design can be achieved.

The invention discloses a dual-polarization filter patch antenna. The dual-polarization filter patch antenna comprises a metal patch, a top dielectric substrate, an intermediate metal sheet, an underlying dielectric substrate and a metal ground. The metal patch is provided with four grooves, an integrated structure formed by the intermediate metal sheet, the underlying dielectric substrate and themetal ground is provided with a plurality of metallized via holes to form a substrate integrated resonant cavity; the two sides of the metal ground are respectively provided with coplanar waveguide feed lines, feed lines excite a pair of orthogonal degenerate modes in a signal feed cavity and pass through a cross recess on the intermediate metal sheet to be coupled to the orthogonal degenerate modes on the metal patch to allow the antenna to obtain second-order filtering response on two polarizations and to have the polarization isolation features, the antenna has the same performances on thetwo polarizations, the structure is simplified, the lengths and the positions of the four grooves are changed to change the external quality factors required on the polarizations, and the isometric coupling line of the terminal short circuit in parallel with the feed lines can generate one radiation zero points at the two ends of the passband to improve the frequency selectivity of the antenna.

The invention discloses a mode demultiplexer of a degenerate mode group based on a spatial three-dimensional waveguide. The mode demultiplexer is characterized in that the mode demultiplexer comprisesa few-mode waveguide and two single-mode waveguides. One end of the first single-mode waveguide is coupled to the few-mode waveguide, and at the coupling position, the axial direction of the first single-mode waveguide is the same as that of the few-mode waveguide; the other end of the first single-mode waveguide is connected with one end of a single-mode straight waveguide through an S-shaped bend waveguide; one end of the second single-mode waveguide is coupled to the few-mode waveguide, and the other end of the second single-mode waveguide is connected with one end of a single-mode straight waveguide through an S-shaped bend waveguide; the other ends of the two single-mode straight waveguides are coupled to one end of a two-mode waveguide, and an included angle formed by connecting lines of circle centers is 90 degrees; a port 1 of the few-mode waveguide receives a few-mode signal in a mixed mode; and the other end of the two-mode waveguide couples the modes LPpqa and LPpqb input into the few-mode waveguide to LP11a and LP11b of the two-mode waveguide correspondingly and then, outputs the modes LP11a and LP11b, wherein p is not equal to 0.

The invention discloses a cascaded etalon filtering system and method for OPO model selection. A temperature controllable three-dimensional adjusting optical etalon is used as a filter device, and thetemperature of the etalon is adjusted to be resonant with the center frequency of an output light field of an optical parametric oscillator (OPO); wide-range filtering is realized by cascading a plurality of etalons with different thicknesses; through an optimized selection scheme of a thickness combination of the etalons, the sideband noise filtering range of the cascaded etalons reaches THz magnitude, and the bandwidth of a transmission spectrum at the center frequency is controlled to be hundred MHz magnitude; the system can be used as a general filtering system for OPO mode selection; a degenerate mode of the OPO is passed, and all the non-degenerate modes are filtered out, so that a filter and an optical cavity cannot be interfered by the narrowband, the cost and the experiment complexity are reduced; and furthermore, the thickness combination of the etalons is optimized, so that the filtering range reaches THz, all the non-degenerate modes of the OPO are covered, and the universality of the filtering system is improved.

A microwave resonator comprising a hollow tube comprising f an electrically conductive tube wall which defines a tube bore, the tube extending along a length axis from a first end to a second end; a first electrically conductive closing plate closing the first end of the tube; a second electrically conductive closing plate closing the second end of the tube; a plurality of dielectric resonant pucks, each puck comprising first and second end faces and a side wall extending therebetween, each puck being dimensioned such that its dominant mode is a doubly degenerate mode; the pucks being arranged within the tube bore spaced apart from each other and the closing plates, each puck being arranged with its end faces normal to the length axis and centered on the length axis and its side wall abutting the tube wall such that there is no air gap between the puck and tube wall which extends from one end face to the other of the puck, the puck adjacent to the first closing plate being termed the input puck; each puck being separated from the adjacent puck in the tube bore by a coupling gap, each coupling gap having ah electrically conductive iris plate arranged therein, each iris plate being arranged normal to the length axis, each iris plate comprising at least one coupling slot extending therethrough; an input microwave coupler adapted to receive a microwave signal and provide it to the input puck; each puck comprising a symmetry breaking structure for modifying the frequency of one of the degenerate modes relative to the other and the coupling between the two modes.

The invention relates to electronic parts and components in communication field, and particularly relates to a dual-mode dielectric filter. The filter comprises a cavity and a cover plate, wherein, inevery two adjacent inner cavities, one inner cavity is internally provided with a metal resonator capable of generating a resonant frequency, and the other inner cavity is internally provided with adielectric resonator capable of generating two resonant frequencies; a first coupling line is arranged between the metal resonator and the dielectric resonator, and a second coupling line is arrangedbetween every two adjacent dielectric resonators. The two degenerate mode resonant frequencies are generated through the dielectric resonators, and the functions of the two cavities can be achieved inthe filter, so that the dimensions can be obviously reduced under same indexes; the two degenerate mode resonant frequencies are independently controlled by the lengths of every two adjacent sides ofa dielectric block, the coupling quantity between two degenerate modes is controlled by the chamfer length of the dielectric block, and the electric parameters of the filter can be accurately controlled by controlling the boundary dimensions of the dielectric block, so that the batch uniformity is guaranteed, and the debugging time is reduced.

The invention discloses a circularly polarized microstrip antenna which comprises a patch array, a feed network, a substrate, and a floor. One face of the substrate is provided with a regular N-polygon metal patch which is in single-point connection with an array microstrip line. When voltage is introduced to the feed network, positive charges gather on the regular N-polygon metal patch, two degenerate modes with orthogonal polarization, equal amplitude and a certain phase difference can be generated. Negative charges gather on the edge of a regular N-polygon hole in the floor on the other face of the substrate, which forms capacitance load with the regular N-polygon metal patch. A rectangular patch plays the roles of increasing propagation path of current and increasing impedance and forms inductance load with a regular N-polygon metal patch coupling short circuit. Separation of resonant frequencies of the two degenerate modes is generated, the impedance phase angle of one mode leadsby 45 degrees, and the impedance phase angle of the other mode lags by 45 degrees, and circularly polarized radiation is formed. The circularly polarized microstrip antenna has the advantages of beingsimple in structure, easy to integrate, process and develop, good in circular polarization performance, and the like.

The invention provides a dual-mode dual-frequency circularly polarized antenna with CSRR distributed control and collar coupling, and relates to a circularly polarized microstrip antenna. A dielectricsubstrate is provided, and upper and lower surfaces of the substrate are covered with good conductors. The upper surface is processed into an inner rectangular sheet and an outer rectangular frame-shaped radiating patch, and the inner rectangular sheet and the outer rectangular frame-shaped radiating patch are connected through four bridges located in the middle of four sides. Four T-shaped slotsare loaded in the middle of the outer side of the radiating patch. In the upper left and lower right corners, ladders of the same size are loaded respectively to control the orthogonal degenerate mode and the circular polarization axis ratio. The internal rectangular patch is a rectangular patch with double cut corners. The cut corners are located on the upper right side and lower left side of the inner rectangular patch. Four complementary open rectangular or circular CSRR resonant ring structures are added near the corners in the inner rectangular patch, wherein each structure is composed of two C-shaped rings with openings nested in each other. Each structure is formed by rotating a CSRR in the upper right corner 90 degrees clockwise. A rectangular grounding plate with double-ring concentric rectangular nested rings is arranged on the lower surface of the substrate, and the rectangular grounding plate and the rings are in interleaved connection through two bridges.

A microwave resonator comprising a hollow tube comprising a plurality of electrically conductive wall faces which together define a tube wall defining a tube bore, the tube extending along a length axis from a first end to a second end; the tube wall having an N fold rotational symmetry about the length axis wherein 2<N<10; a first electrically conductive covering plate covering the first end of the tube; a second electrically conductive covering plate covering the second end of the tube; a dielectric puck comprising first and second end faces and a side wall extending therebetween, the puck being dimensioned such that when in the tube bore its dominant resonant mode is a doubly degenerate mode; the puck being arranged in the tube bore spaced apart from the covering plates with its end faces normal to the length axis and centered on the length axis; the puck being spaced apart from the tube wall by a plurality N of electrically conductive spacer blocks, the spacer blocks being spaced equally around the length axis and spaced apart from the covering plates; and, a symmetry breaking structure adapted to modify the coupling between the two degenerate modes and also their relative frequencies.

The invention discloses a few-mode optical fiber space mode field detection method based on an interference theory. The method comprises the following steps: firstly, obtaining a mode component whichcan be supported by a to-be-tested optical fiber at a related wavelength through simulation software; then, based on the interference theory, extracting measurable characteristic parameters reflectingthe complex intensity of the degenerate mode; secondly, by establishing an equation set of the characteristic parameters and the degenerate mode complex intensity, obtaining the complex intensity ofeach degenerate mode from a physical image through algorithm processing, and designing a related algorithm to realize the idea. On the experimental level, a set of optical device for detecting an optical fiber emergent mode field is built, and a space image detector is used for recording mode spots; on the image detected by the space image detector, the complex intensity of the corresponding degenerate mode of each order can be obtained by applying the mode recovery algorithm. According to the method, the complex amplitude for restoring the degenerate mode can be calculated, and the method ismore accurate compared with a traditional method that only the module strength can be obtained.