30results about How to "Adjustable center frequency" patented technology

The invention discloses a distributed optical fiber sensing device based on a chaotic laser coherence method, and a measurement method of the distributed optical fiber sensing device. Chaotic laser light which is emitted from a chaotic laser is divided into detection light and reference light; the detection light is amplified by a light amplifier and then emitted into a sending optical fiber through an optical circulator, and a backward Brillouin scattering light signal is generated in the optical fiber; the Brillouin scattering light signal is amplified by the light amplifier, de-noised by a tunable light filter and then emitted into an optical fiber coupler; the optical length of the reference light is regulated by a variable light delay line, and interferes with the backward Brillouin scattering light signal which is generated by the detection light at different positions in the sensing optical fiber in the optical fiber coupler; an interference beat frequency signal is detected by a photoelectrical detector; and Brillouin gain spectra at different lengths are obtained through a data acquisition device and a signal processing device and then output to a display device, so strain or temperature sensing detection is realized.

The invention discloses an optical bandpass filter based on a double microring-Mach Zehnder interference structure. The optical bandpass filter is composed of a first multi-mode interference coupler, a second multi-mode interference coupler, a third multi-mode interference coupler, a first coupling grating, a second coupling grating, a first heating electrode, a second heating electrode, a third heating electrode, a fourth heating electrode, a first upload-download type micro ring, and a second upload-download type micro ring. According to the invention, on the basis of the design of the coupling states of two upload-download type micro rings, fully destructive interference is introduced based on a cascaded adjustable Mach Zehnder interference (MZI) structure; amplitude regulation is realized by adjusting the bias voltage on the heating electrode of the MZI1, so that amplitudes of passband external light signals of an upper arm and a lower arm becomes identical; and phase regulation is realized by adjusting the bias voltage on the heating electrode of the MZI2, so that phases of passband external light signals of the upper arm and the lower arm are opposite. Therefore, the extinction ratio of the filter increases under the circumstance that the passband insertion loss is not increased. The provided optical bandpass filter has advantages of narrow bandwidth, high extinction ratio, and low insertion loss.

An ultrahigh Q-value single-passband microwave photon filter comprises a tunable filter, an optical coupler, a single-sideband modulation module, a single-sideband suppression carrier modulation module, a microwave signal source, an optical isolator, an optical amplifier, a single-mode optical fiber, an optical circulator, an optical fiber circulation cavity, a photoelectric detector and a vectornetwork analyzer, wherein the tunable filter is connected with the optical coupler, the optical coupler is connected with the single-sideband modulation module and the single-sideband suppression carrier modulation module, the optical isolator is connected with the single-sideband modulation module, the single-mode optical fiber is connected with the optical isolator, the microwave signal source is connected with the single-sideband suppression carrier modulation module, the single-sideband suppression carrier modulation module is connected with the optical fiber amplifier, the optical fiber amplifier is connected with the optical circulator, the optical fiber circulation cavity is connected with the optical circulator and is connected with the photoelectric detector, the photoelectric detector is connected with the vector network analyzer, and the vector network analyzer is connected with a microwave of the single-sideband modulation module.

The invention discloses an adjustable transformer. A circuit structure is composed of a port 1 (Port 1), a port 2 (Port 2), resistors, capacitors and inductors, wherein coupling is existed between two inductors, two circuit units are connected through a coupling capacitor, and the central frequency and out-of-band transmission zero point of the transformer can be regulated through changing values of a resonant capacitor and a coupling capacitor. The adjustable transformer can realize wide band width and can be broadly used for 5G mobile communication power dividers and the like which are strict in signal performance; the adjustable transformer is capable of reducing the out-of-band noise and improving the electronic circuit stability.

The invention discloses wireless telecom equipment with the reconfigurable carrier frequency and the reconfigurable signal bandwidth and relates to the field of wireless communication. The technical key points are that a local oscillator unit of an up-conversion unit in an emitting channel and a local oscillator unit of a down-conversion unit in a receiving channel are chosen as frequency-adjustable local oscillator units, a control unit is utilized to control the signal frequency output by the local oscillator units, accordingly the center carrier frequency of the emitting channel or the receiving channel is adjustable, meanwhile an emitting filter of the emitting channel and a receiving filter of the receiving channel can be replaced in a mechanical installation method to achieve different bandwidth ranges and different center frequency filtering effects, and the signal bandwidth can be changed. Furthermore, the center frequency of the emitting filter and the center frequency of the receiving filter are respectively equal to the local oscillator signal frequency output by the emitting local oscillator unit and the local oscillator signal frequency output by the receiving local oscillator unit.

The invention discloses a micro-strip dual-frequency adjustable band-pass filter based on a folding split ring. Resonator coupling is adopted to form a dual-frequency band-pass filter, varactors are respectively loaded at an opening of an open-loop resonator and a terminal of a stepped impedance resonator, and the capacitance value is changed by changing an external voltage, so that the resonant frequency of the filter is changed, and dual frequency bands of the filter are independent and adjustable.

The invention provides a three-notch ultra-wideband filter based on defected microstrip structures, which comprises a microstrip substrate, and a first input / output port, a second input / output port, a first uniform line transmission unit, a second uniform line transmission unit, a first parallel coupled feeder, a second parallel coupled feeder and an E-type multimode resonant structure arranged on the microstrip substrate, wherein a first defected microstrip structure, a second defected microstrip structure and a third defected microstrip structure are arranged on the E-type multimode resonant structure; and each defected microstrip structure is formed by three linear grooves connected in sequence and with the same width in the E-type multimode resonant structure. Three-notch features are provided, the central frequency of the notch is adjustable through adjusting the length of the defected microstrip structure, and product debugging and batch production are facilitated.

A tunable ultra-narrow linewidth optoelectronic oscillator based on a random Brillouin fiber laser is provided, comprises a first tunable laser (1), a second tunable laser (2), a coupler (3), a beam splitter (4), an intensity modulator (5), an erbium-doped fiber amplifier (6), a first circulator (7), a highly nonlinear optical fiber (8), a second first circulator (9), a single-mode optical fiber (10), a photodetector (11), a power divider (12) and a phase-locked loop system (13) which constitute a real-time feedback system so that the two lasers emitted by the two tunable lasers have a fixed and stable phase difference. The microwave signal with adjustable center frequency and narrow linewidth can be generated by using the modulating characteristic of intensity modulator, nonlinear characteristic of high nonlinear fiber, feedback characteristic of single mode fiber, wavelength tunable characteristic of tunable laser and microwave generation performance of photoelectric oscillator.

The invention discloses a bandwidth and center frequency adjustable three-passband filter based on a single multimode SIW cavity. The three-passband filter comprises a polygonal dielectric substrate,a metal layer is arranged on the upper surface of the dielectric substrate, and the lower surface of the dielectric substrate is provided with a metal grounding plate. The dielectric substrate is respectively provided with an input port feeder line and an output port feeder line, a central metal perturbation through hole, a first metal perturbation through hole group, a second metal perturbation through hole group, a first side metal perturbation through hole and a second side metal perturbation through hole are formed in the dielectric substrate, and a first rectangular perturbation groove and a second rectangular perturbation groove are etched in the upper surface metal layer.

The invention discloses a plane low-pass band-pass dual-frequency filter which is manufactured on a dielectric substrate in a printed circuit board manner. An input end feeder line port 1 for inputting an electromagnetic wave signal, an output end feeder line port 2 for outputting an electromagnetic wave signal, a first transmission line (1), a second transmission line (2), a third transmission line (3), a fourth transmission line (4), a fifth transmission line (5), a six transmission line (6) and a seventh transmission line (7) are manufactured on the same surface of the dielectric substrate; an earth plate is arranged on the other surface of the dielectric substrate. On the premise that the low-pass characteristic is not changed, the band-pass center frequency can be adjusted in a large range; the filter comprises an open circuit transmission line and a high impedance line, enables the band-pass center frequency to be independently adjusted within a larger range by adjusting the electrical length and characteristic impedance of the transmission lines, and has the advantages of adjustable frequency, good selectivity, low loss and simple structure.

The invention provides an antenna matching circuit. The circuit comprises an adjustable matching circuit connected with an antenna, and a control unit connected with the adjustable matching circuit; the adjustable matching circuit comprises a dielectric substrate, a 50-omega microstrip connecting line, a microstrip transmission line, a microstrip open-circuit branch, an adjustable varactor diode and a capacitor bias circuit; the control unit is used for obtaining the real-time load of the antenna and adjusting the capacitance value of the adjustable varactor diode; the 50-omega microstrip connecting line is an input microstrip connecting line; the microstrip transmission line comprises a first microstrip transmission line, a second microstrip transmission line and a third microstrip transmission line; and the microstrip open-circuit branch envelops the first microstrip open-circuit branch, the second microstrip open-circuit branch and the third microstrip open-circuit branch. Accordingto the invention, when the antenna load changes, the center frequency of the matching circuit can be adjusted, the real part change of the antenna load impedance is 50 omega, the imaginary part change is 50 omega, the output port can be matched in real time, and the antenna matching circuit has the advantages of being flexible in design and easy to tune.

The invention discloses a frequency double-chirp microwave waveform generation method and device, and belongs to the technical field of optics and microwaves. The method comprises the following steps: S1, generating an optical carrier and a modulation signal, and performing phase modulation on the optical carrier to generate first-order sideband phase modulation signals with the same amplitude and opposite phases; S2, filtering a first-order sideband of the phase modulation signal to realize conversion from phase modulation to intensity modulation; S3, enabling the frequency change period of the phase modulation signal without the first-order sideband to be synchronous with the loop time of the phase modulation signal in the photoelectric oscillation loop or to be integral multiples of the loop time, and achieving Fourier domain mode locking; S4, converting the phase modulation signal with one first-order sideband filtered out into a dual-passband microwave signal after delayed energy storage, dividing the dual-passband microwave signal into two paths, taking one path as a modulation signal to form a photoelectric oscillation loop, and taking the other path as a radio frequency signal to be output. The device provided by the invention realizes the generation of multi-band linear double-chirp microwave waveforms with continuous and tunable frequency.

The invention provides a planar transmission line structure for improving ferromagnetic resonance linewidth test precision, and belongs to the field of microwave millimeter wave band magnetic material parameter test. The planar transmission line structure comprises a first-stage standard characteristic impedance grounding coplanar waveguide, a first-stage non-standard microstrip line, an intermediate-stage non-standard characteristic impedance grounding coplanar waveguide, a second-stage non-standard microstrip line and a second-stage standard characteristic impedance grounding coplanar waveguide which are sequentially connected in series; the characteristic impedance of the first-stage standard characteristic impedance grounding coplanar waveguide, the characteristic impedance of the second-stage standard characteristic impedance grounding coplanar waveguide, and the characteristic impedance of a transmission line composed of the first-stage non-standard microstrip line, the middle-stage non-standard characteristic impedance grounding coplanar waveguide and the second-stage non-standard microstrip line are 50 ohms. The signal line width and the slot spacing of the middle-stage non-standard characteristic impedance grounding coplanar waveguide are process limit values; and the lengths of the first-stage and second-stage non-standard microstrip lines are 1 / 4 of the central frequency wavelength. Through multi-stage transmission line conversion, the grounding coplanar waveguide with the signal line width and the groove spacing being the process limit values is realized, and the test precision is improved.

The invention discloses a reconfigurable optical all-pass filter. The reconfigurable optical all-pass filter comprises three optical couplers, N+2 optical phase shifters and N micro-rings, wherein the output end of the first optical coupler, the input end of the second optical coupler and the first optical phase shifter form an MZI1 structure, and the output end of the second optical coupler, the input end of the third optical coupler, the second optical phase shifter, the third optical phase shifter and the first micro-ring form an MZI2 structure. The interference characteristic of a Mach-Zehnder interferometer and the resonance characteristic of a micro-ring are utilized, a signal is input into a chip and is divided into two paths through an MZI1 structure to be input into an MZI2 structure, one path of signal is filtered by the micro-ring, and the other path of signal passes through the phase shifters and a waveguide, the two paths of signals are interfered by the third optical coupler, are processed by the plurality of cascaded all-pass micro-rings, and are finally output from the second coupling grating. By changing the amplitude ratio and the phase difference of the two paths of signals and adjusting the coupling coefficient of the micro-ring, flat amplitude-frequency response is realized, so that the all-pass filter is realized.

The invention discloses a substrate integrated waveguide filter with independently adjustable double bands. The substrate integrated waveguide filter comprises a resonant cavity and a perturbation body on the resonant cavity, wherein the resonant cavity comprises a ground plane, a dielectric plate, a top-layer surface and metal wall via holes; the top-layer surface and the ground plane are located at the upper part and the lower part of the dielectric plate; the metal wall via holes are distributed in the periphery of the resonant cavity in an array at equal distances to form a wall; the hole pitch between two metal wall via holes is smaller than or equal to 2.5 times of the diameter of each metal wall via hole; the perturbation body comprises a perturbation trough, perturbation metal via holes and connecting troughs; the perturbation trough is located at the center position of the top-layer surface of the resonant cavity; the connecting troughs are symmetrically arranged about the perturbation trough; the perturbation metal via holes in each resonant cavity are symmetrical about the perturbation trough and correspondingly located in the connecting troughs; and the numbers of the connecting troughs and the perturbation metal via holes are even numbers. The SIW filter with the independently adjustable double bands has the advantages of being simple in structure, relatively large in return loss, independently adjustable in double bands and simple in operation.

The invention discloses a planar low-pass band-pass dual-frequency filter, which is fabricated on a dielectric substrate in the form of a printed circuit board, and the same surface of the dielectric substrate is respectively fabricated with an input terminal feeder head port1 for inputting electromagnetic wave signals, Output feeder head port2 for outputting electromagnetic wave signals, first transmission line (1), second transmission line (2), third transmission line (3), fourth transmission line (4), fifth transmission line (5), sixth transmission line (6) The seventh transmission line (7), the other side of the dielectric substrate is a ground plate. The planar low-pass band-pass dual-band filter disclosed by the present invention can adjust the band-pass center frequency in a large range under the premise of ensuring that the low-pass characteristics remain unchanged. The filter is composed of an open-circuit transmission line and a high-impedance line. The length and characteristic impedance enable the band-pass center frequency to be independently adjusted within a wide range, and has the advantages of adjustable frequency, good selectivity, low loss, and simple structure.

The invention discloses a tunable photoelectric oscillator based on PT symmetric combination with a high-Q resonator, and belongs to the field of microwave photonics. The tunable photoelectric oscillator comprises a continuous light laser light source, a polarization controller, a phase modulator, a high-Q resonator, a Mach-Zehnder interferometer, a photoelectric detector, an electric amplifier and an electric power divider. a light carrier output by the laser enters the phase modulator, a microwave signal is modulated to the light carrier through the phase modulator and input to the high-Q resonator, a tunable microwave photonic filter is obtained, delay and preliminary mode selection are performed on the microwave signal, mode selection is further enhanced in combination with PT symmetric breaking on the basis, finally, a microwave signal carried on an optical signal is detected through a photoelectric detector, positive feedback is introduced through the photoelectric oscillator loop, and the microwave signal is finally output. According to the invention, the high-Q resonator is used for time delay and preliminary mode selection, and PT symmetric breaking enhancement mode selection is further combined, so that the output frequency tunable photoelectric oscillator is realized.

The invention provides a system for generating a center-frequency-variable high-speed linear frequency modulation signal based on a phase-locked loop, and belongs to the field of radio frequency. Thesystem comprises an operational amplifier, a single-chip microcomputer, a phase-locked loop, a crystal oscillator, a loop filter, an adder, a voltage-controlled oscillator and a directional coupler. The operational amplifier is connected with the adder, the single-chip microcomputer and the crystal oscillator are both connected with the phase-locked loop, the phase-locked loop is connected with the adder through the loop filter, the adder is connected with the directional coupler through the voltage-controlled oscillator, and the directional coupler is connected with the phase-locked loop. According to the invention, the phase-locked loop is used to accurately lock the center frequency of the output chirp signal; the modulation signal and the direct current signal output by the phase-locked loop are superposed through the adder; the size of the linear frequency modulation signal and the sweep frequency bandwidth are controlled, the single-chip microcomputer is used to control the switching of the center frequency, the purposes of ultra wide band and adjustable center frequency are achieved, the response speed of the sweep frequency signal is ensured by using a direct driving mode,and higher and higher performance requirements can be satisfied.

The invention discloses an adjustable negative group delay circuit, aiming to provide a negative group delay circuit with simple structure, low circuit insertion loss and no need for input and output matching circuits. The adjustable negative group delay circuit of the present invention includes: a section of microstrip line connected in series between the input port and the output port and N dielectric resonators with adjustable resonant frequency and unloaded quality factor, wherein: N adjustable dielectric resonators The resonator is equivalent to N different parallel RLC resonant circuits, which are located next to the microstrip line and fixed on the same printed board as the microstrip line; N dielectric resonators work in the transverse wave TE mode and are connected to the microstrip through wireless coupling. After the strip line is coupled with the microstrip line, N-band negative group delay is generated near the resonant frequency of N dielectric resonators; the input port impedance and output port impedance of the adjustable negative group delay circuit are the same as the microstrip line impedance. The invention can be widely used in technical fields requiring negative group delay and adjustable negative group delay.

An ultrahigh Q-value single-passband microwave photon filter comprises a tunable filter, an optical coupler, a single-sideband modulation module, a single-sideband suppression carrier modulation module, a microwave signal source, an optical isolator, an optical amplifier, a single-mode optical fiber, an optical circulator, an optical fiber circulation cavity, a photoelectric detector and a vectornetwork analyzer, wherein the tunable filter is connected with the optical coupler, the optical coupler is connected with the single-sideband modulation module and the single-sideband suppression carrier modulation module, the optical isolator is connected with the single-sideband modulation module, the single-mode optical fiber is connected with the optical isolator, the microwave signal source is connected with the single-sideband suppression carrier modulation module, the single-sideband suppression carrier modulation module is connected with the optical fiber amplifier, the optical fiber amplifier is connected with the optical circulator, the optical fiber circulation cavity is connected with the optical circulator and is connected with the photoelectric detector, the photoelectric detector is connected with the vector network analyzer, and the vector network analyzer is connected with a microwave of the single-sideband modulation module.

The invention belongs to the technical field of microwave communication equipment, and particularly relates to a dual-mode SIW tunable filter based on reconfigurable electromagnetic boundaries, which includes a square substrate integrated waveguide dual-mode resonator, multiple PIN diodes and input and output feeders; The axisymmetric position of the square substrate integrated waveguide dual-mode resonator is added with a perturbation slot, and the main mode TE is used 101 modulus and the first higher order modulus TE 102 The mode forms the passband of the filter; PIN diodes are loaded around the square substrate integrated waveguide dual-mode resonator to control the free switching of the electrical boundary and the magnetic boundary; the input and output feeders are connected with the square substrate integrated waveguide dual-mode resonator connected. The present invention proposes the idea of ​​using the on-off of the PIN diode to realize the reconfigurable electromagnetic boundary, realizes the adjustable center frequency and keeps the absolute bandwidth constant, and has good selectivity and out-of-band suppression level in the entire center frequency adjustment range. The whole filter circuit has a simple structure and is flexible and convenient to adjust.

The invention discloses a compact electrically tunable balanced band pass filter. The filter comprises an upper layer of a microstrip line structure, a middle layer of a dielectric substrate and a lower layer of a grounding metal patch and metal through holes. The microstrip line structure comprises a multimode resonator and two pairs of input / output feeders. The multimode resonator comprises a first microstrip line and a second microstrip line which are symmetrical up and down; the first microstrip line and the second microstrip line are all E-shaped; the first microstrip line faces downwards; the second microstrip line faces upwards; the microstrip branch lines at the left and right two sides of the first microstrip line are connected with the microstrip branch lines at the left and right two sides of the second microstrip line respectively through two variable capacitance diodes which are connected in series; the central microstrip branch line of the first microstrip line is connected with the central microstrip branch line of the second microstrip line through two variable capacitance diodes which are connected in series; and a section of short microstrip branch line is loaded at the center of the two variable capacitance diodes which are connected in series. According to the filter provided by the invention, the central frequency of a passband is tunable; and the bandwidth is tunable.

The invention discloses a reconfigurable optical all-pass filter, comprising: three optical couplers, N+2 optical phase shifters and N microrings; the output end of the first optical coupler, the second optical coupler The input terminal and the first optical phase shifter constitute the MZI 1 Structure, the output end of the second optical coupler, the input end of the third optical coupler, the second optical phase shifter, the third optical phase shifter and the first microring constitute the MZI 2 structure. The invention utilizes the interference characteristics of the Mach-Zehnder interferometer and the resonance characteristics of the microring to input the signal into the chip and pass through the MZI 1 structure is divided into two inputs to the MZI 2 structure, one signal is filtered by the microring, the other one passes through the phase shifter and waveguide, the two signals are processed by multiple cascaded all-pass microrings after the interference of the third optical coupler, and finally from the second coupling grating output. The invention realizes a flat amplitude-frequency response by changing the amplitude ratio and phase difference of the two signals and adjusting the coupling coefficient of the micro-ring, thereby realizing an all-pass filter.

The invention belongs to the technical field of radar signal generation, in particular to a multi-frequency signal generation method. The invention utilizes the DDS chip, supplemented by FPGA control, uses tools such as matlab to calculate the phase waveform data in a cycle, and writes the data into the DDS chip RAM through hardware logic. The curve and the preset playback rate will play the signal to complete the multi-frequency signal modulation.

The invention discloses an optical all-pass filter. The optical all-pass filter comprises a first optical coupler, a second optical coupler, a first coupling grating, a second coupling grating, first, second, third and fourth optical phase shifters and a microring. By use of frequency response characteristics of the microring, two ways of signals with adjustable amplitudes and phases are transmitted into the microring from two different ports of the microring respectively and are output at the two ports of the microring after being subjected to interfered beam combination. Different system phase response spectrum widths are realized by changing the coupling state of the microring, system amplitude response is a constant unrelated to frequency through adjustment of the amplitudes and phases of the two ways of signals, so that the optical all-pass filter is obtained. On the basis of the optical all-pass filter, the invention discloses a microwave photonic filter with a high Q value and an ultrahigh inhibition ratio and a microwave photonic phase shifter with a broad work frequency range and no sinking of amplitude response in the work range.

The invention provides an active filtering device adjustable to fit various specifications. A first filter has a first quality factor to define the frequency width and the center frequency of the filtering device; a second filter is connected to the first filter and has a second quality factor, and the frequency spectrums of the first filter and the second filter are used for defining the frequency of the filter at low frequency in frequency width and the sharpness of the frequency width at low frequency in the frequency width; a third filter is connected to the second filter and has a third quality factor, and the frequency spectrums of the first filter and the third filter are used for defining the frequency of the filter at high frequency in the frequency width and the sharpness of the frequency width at high frequency in the frequency width; the value of the first quality factor is adjustable, and the adjustment range is between 5 and 15; and the value of the second quality factor and the third quality factor is adjustable, and the adjustment range is above 15.

The invention relates to a high-power radiator with adjustable frequency. The radiator with adjustable center frequency can be realized by changing the length of the antenna vibrator, the discharge distance and the air pressure. Combined with the charging power source and the pulse power source platform, different frequencies can be output in the same system. Radiation field of high power electromagnetic pulses. Compared with ordinary high-power broadband antennas, the present invention has the following characteristics: 1. Adjustable radiation frequency: under the excitation of the same pulse power source, the adjustment of the radiation frequency can be realized by replacing the vibrators with different lengths in the radiator without using Different power sources reduce the requirements and costs of EMP effects testing. 2 Adjustable discharge spacing: By setting the electrode spacing of the discharge switch to be adjustable outside the radome, the array of radiators can be realized and a higher radiation field strength can be obtained.