289 results about "Passband filter" patented technology

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

Methods and apparatus are described herein that make use of complex tuning, the inherently repetitive nature of sampled signals, and programmable digital filtering to create a flexible digital up-conversion system that utilizes a digital-to-analog converter (DAC) with a fixed effective sample rate while still being adapted for tunability over a wide frequency range. With a knowledge of the fixed effective sample rate of the DAC and a desired frequency of up-conversion and combining complex tuning at baseband and up-sampling by a factor of N with a programmable passband filter configured to select one of a plurality of signal images resulting from the up-sampling, it is possible to translate a baseband input signal to a wide range of frequencies above or below F_s, without changing the sampling rate of the fixed rate DAC used in the up-conversion process.

The invention relates to a method and an apparatus for agile RF spectrum monitoring in a radio system with dynamic frequency access. It provides a spectrum monitor based on non-coherent heterodyne detection that utilizes a DDS signal generator to digitally generate a reference signal at a variable reference frequency for mixing with an input RF signal received from an RF antenna, a pass-band filter and a log amplifier for obtaining energy estimates at a monitored transmission frequency corresponding to the reference frequency. A processor is provided for adaptively selecting sets of monitored transmission frequencies, for controlling the DDS signal generator, and for processing obtained spectral energy estimates to assess spectral usage data.

The invention discloses a double frequency band filter of a SIR coaxial cavity. The double frequency band filter of the SIR coaxial cavity comprises a CQ-type topological structure formed by coupling of a coaxial SIR in magnetic and galvanic modes. The coaxial SIR is composed of a rod-shaped inner layer metal transmission line, an outer layer barrel-shaped metal wall and a middle medium layer, wherein the outer layer barrel-shaped metal wall shares the same axis with the inner layer metal transmission line which is formed by connecting of two coaxial transmission lines with different diameters. A terminal opening end coaxial borehole is formed at the top end of a terminal opening end of the metal transmission line, and a tuning screw is placed at the top end of the terminal opening end of the metal transmission line to tune. The double frequency band filter is provided with the CQ-type topological structure of 8 cavities, two transmission zeroes are generated on the outside of a double frequency band, so that out-of-band suppression performances are greatly improved. Compared with a traditional duplexer, the double frequency band filter is improved on the aspects of size miniaturization and design complexity in quality mode. The double frequency band filter has the advantages of being small, low in insertion loss, high in double frequency selection properties and the like. The demands on filter performances by a modern communication system are met, and the double frequency band filter can be widely applied in double frequency band mobile communication systems.

The invention discloses a multi-passband filtering method of railroad bed disease detection ground penetrating radar signals. The filtering method comprises steps of automatically acquiring roadbed original radar data through a vehicle-mounted roadbed detection radar; extracting radar reflection signals at joints of all scanning channel sleepers so as to form a digital sequence, and obtaining frequency spectrum features of the sleepers and the rail strong reflection interference signals by carrying out frequency spectrum analysis on the digital sequence; designing a multi-passband filter used for inhibiting strong interference of the sleepers and the rails; and using the filter to successively filter the radar signals according to sampling points so as to remove interference signal. According to the invention, by analyzing the strong reflection interference signals of the rails and the sleepers in the railroad bed disease detection ground penetrating radar signals for the first time, sleeper identification device is not required, radar signal acquisition is carried out without avoiding the rails, and the multi-passband filter designed on the basis of strong interference frequency spectrum features of the rails and the sleepers is used for removing strong reflection interference of the sleepers and the rails, the signal to noise ratio of reflection radar signals of the roadbed medium is improved.

A dual-band semi-active laser (SAL) sensing system incorporating a dual-passband filter. According to one example, a semi-active laser sensing system includes a detector assembly and an aperture lens. The SAL sensing system further comprises a dual-passband filter having a stopband, a first passband and a second passband, the first and second passbands being distinct and non-overlapping and spectrally separated from one another by a portion of the stopband, the filter being configured to receive the electromagnetic radiation from the aperture lens and to filter the electromagnetic radiation to pass a first wavelength range within the first passband and a second wavelength range within the second passband. The SAL sensing system further includes a lens assembly configured to receive the first and second wavelength ranges from the filter and to focus the first and second wavelength ranges onto the detector assembly.

The invention discloses a method for manufacturing a novel terahertz ultra-wide pass band filter. The method includes cleaning a substrate, coating a polyimide film on the substrate, coating a photoresist lift off resist (LOR) on the polyimide film and drying, coating a photoresist AZ1500 on the photoresist LOR and drying, exposing the photoresist, subjecting the exposed photoresist to development and drying, vaporizing a first layer of metal on the photoresist AZ1500 and the exposed polyimide film, soaking the substrate which is subjected to vaporizing the first layer of metal in an acetone solution for lift-off, coating the polyimide film on the substrate and curing, vaporizing a second layer of metal on the photoresist AZ1500 and the exposed polyimide film, soaking the substrate which is subjected to vaporizing the second layer of metal in the acetone solution for lift-off, coating the polyimide film on the substrate and curing, removing the substrate, and lifting off the substrate and the polyimide film. The method for manufacturing the novel terahertz ultra-wide pass band filter has the advantage that the expansion of frequency bands is achieved.

The invention discloses a small differential tee band-pass filter and solves the problems of multi-frequency operation of a differential band-pass filter and common-mode noise suppression. The filter comprises a micro band structure, a micro band medium substrate, a metal grounding plate and a defective ground structure; the micro band structure is transversely symmetric about the longitudinal central axis of a filter body; two side U-type differential input and output ports in the same structures are provided and are located on the upper surface of the micro band medium substrate; the defective ground structure is arranged on the metal grounding plate in an etched manner, and the defective ground structure is transversely symmetric about the longitudinal central axis of the filter body and comprises three complementary opened resonant rings, an input clearance line and an output clearance line; the complementary opened resonant rings are embedded mutually in a surrounded manner corresponding to the center of the metal grounding plate from interior to exterior, the input and output clearance lines are in stepped impedance types, and the defective ground structure is reduced accordingly. The differential filter miniaturization is realized, the central frequency and bandwidth of three differential mode pass bands are controlled independently, and the fine broadband common mode suppression features are provided.

The invention discloses an electrically tunable four-passband filter based on a double layered resonator, and mainly solves the problems that the number of passbands of a traditional electrically tunable filter is small, adjustable passband bandwidth is not constant, the out-of-band rejection degree is poor and the volume is large. The electrically tunable four-passband filter based on the double layered resonator includes a pair of parallel coupling feeder lines (1) and a pair of adjustable stepped impedance resonators (2, 3) which are arranged on an upper microstrip medium substrate (7), and a branch loading resonator (4) and two direct current biasing circuits (5, 6) which are arranged on a lower microstrip medium substrate (8), wherein the two direct current biasing circuits (5, 6) are connected to two ends of the adjustable stepped impedance resonators (2) and (3), thereby realizing continuously adjustability of a third passband and a fourth passband, and the branch loading resonator (4) realizes fixing of a first passband and a second passband. The electrically tunable four-passband filter based on the double layered resonator is small in size and high in out-of-band rejection degree, can realize four passbands, realizes continuous adjustability of the third passband and the fourth passband under the condition that the bandwidth is basically maintained unchanged, and can be used for a wireless communication system.

The invention belongs to a multi-band bandstop filter comprising N resonant cavity groups. N is a the number of bands and is in a closed interval from 2 to 4; the N resonant cavity groups are stacked and aligned to acquire the response of the multi-band bandstop filter; each resonant cavity group comprises n resonant cavities arranged in a line, and n is in a closed interval from 3 to 5; distance among the n resonant cavities belonging to the same resonant cavity group is odd times of a 1/4 wavelength; a rectangular waveguide is in a 3/4 waveguide wavelength; and the N resonant cavity groups share the same main passage, are parallel to the main passage and are arranged at one side of the main passage or at both sides of the main passage by being arranged in an overlapping way while less than two resonant cavity groups are arranged at either side. The stopbands of the multi-band bandstop filter have good rejection characteristics and inter-stopband passband characteristics so that the multi-band bandpass filter can be designed by applying the structure of the multi-band bandstop filter based on a design idea that a bandpass filter and an N-band bandpass filter are integrated into an N+1-band multi-band bandpass filter.

The invention discloses a multi-bandpass filter based on a multimode resonator and mainly solves the problem of large size and poor performance of the multi-bandpass filter. The multi-bandpass filter based on the multimode resonator comprises a micro-strip dielectric substrate (1), a metal earth plate (2), a resonator (3) and an input-output feeder line (4). The resonator (3) is composed of two identical five-mode resonators which are staggered, each five-mode resonator is composed of a short-circuit branch (31), an open-circuit branch (32), a U-shaped microstrip line (33), a bulged loop (34) and L-shaped open-circuit branches (35 and 36). The symmetric center of the bulged loop (34) is superposed with that of the U-shaped microstrip line, and the top end of the bulged loop is connected with the bottom end of the U-shaped microstrip line. The L-shaped open-circuit branches are connected at the bottom end of the U-shaped microstrip line. The input-output feeder line (4) is composed of a pair of quasi fork-finger type coupled feeder lines. The size of the multi-bandpass filter can be reduced, design complexity is reduced, bandpass selectivity is improved, and the multi-bandpass filter can be used for a wireless communication system.

A filter circuit is provided having multipath interference mitigation. The filter includes a signal path extending from an input to an output. The signal path includes a conductive path and a ground. A pass band filter is disposed along the signal path between the input and the output. The pass band filter passes a first frequency spectrum in a provider bandwidth, and attenuates a second frequency spectrum in a home network bandwidth. The filter circuit further includes a multipath interference mitigation leg operatively branched from the signal path. The multipath interference mitigation leg increases a return loss of the home network bandwidth. A frequency response of the filter circuit is characterized by an insertion loss characteristic between the input and the output being less than 3 dB in the provider bandwidth, and more than 20 dB in the home network bandwidth. The frequency response is further characterized by a return loss characteristic at the output being more than 10 dB in the provider bandwidth and home network bandwidth.

The invention provides a triple-band band-pass filter based on an openstub loaded resonator, and mainly solves the problems in the design of the multi-passband filter that the size of the filter is large, the internal insertion loss of the passband is high and the echo loss is low. The triple-band band-pass filter comprises a microstrip dielectric substrate (1), a metal grounding plate (2), resonators (3), input and output feed lines (4) and a grounding through hole (5). The metal grounding plate (2) is arranged on the lower surface of the dielectric substrate (1). The resonators (3) are connected in series between the input feed line (41) and the output feed line (42). The resonators (3) and the input feed line (41) and the output feed line (42) are arranged on the upper surface of the dielectric substrate (1). According to the filter, the overall size of the filter can be reduced, the extremely low insertion loss can be acuqired and each passband can be independently controlled so that stop-band suppression can be increased, the passband selectivity can be enhanced and the triple-band band-pass filter can be used for the WLAN and WIMAX wireless communication system.

The invention discloses a multi-target micro-vibration video amplification method based on a multi-passband filter, and the method comprises the following steps: S1, photographing a multi-target vibration video through a camera, carrying out the YIQ color space conversion of the video, and extracting the video data of a Y channel; S2, in the Y video, manually selecting an ROI (region of interest)region containing the edge of the first vibration target, extracting brightness signals at N pixel positions in the region, and calculating an average frequency spectrum of the signals; similarly, obtaining the average frequency spectrum of other M-1 vibration targets; and then, detecting vibration frequencies and frequency peak values of the M targets to obtain a frequency vector and a frequencypeak value vector; S3, designing a multi-passband filter according to the sum of the frequency vectors; S4, replacing a band-pass filter in the PVM method with a filter to realize amplification of theM target micro-vibration videos. The multi-target micro-vibration video amplification method provided by the invention has the advantages of realizing multi-target micro-vibration visual display andthe like.

The invention provides an electromagnetic band gap (EBG) substrate-based resonator/filter. A top layer metal plate, a bottom layer metal plate, a middle dielectric layer, periodical metal columns and an external control network which consists of a series of resonator/filter working frequency control elements are included, wherein the periodically-arranged metal columns are embedded in the dielectric layer to form the periodical EBG substrate; an energy coupling structure designed on the top layer metal plate consists of coplanar waveguide and groove lines; and the frequency control elements can be built in or externally connected with a capacitor, and are connected with a central metal column to jointly form a resonant network to realize frequency tuning. On the basis, a dual-passband filter is also provided; the dual-passband filter comprises two or more EBG substrate-based single-band filters, and the external control network which consists of a series of frequency control elements. The single-band filters share the EBG substrate, so that miniaturization and high performance of the filter are realized.

The invention discloses a double-passband filter with a left-hand performance, comprising a grounding plate, a central transmission line, a hollow-out split resonant ring and split-ring resonators, wherein, the hollow-out split resonant ring is etched on the grounding plate; the grounding plate is equipped with a medium plate; the central transmission line is arranged on the medium plate, two ends thereof are respectively connected with an external signal input cable and an external signal output cable, two sides thereof are symmetrically equipped with two split-ring resonators, and the central position thereof is etched with a slit; and the central transmission line at two sides of the slit is etched with a plurality of through holes on the grounding plate. The double-passband filter helps a signal passing the same have the left-hand performance and small structural physical dimensions.

The invention discloses a dual-passband power amplifier integrated with a filter. One end of an inductor L1 is connected with a negative voltage, while the other end of the inductor L1 is connected with one end of a microstrip line R1 and one end of a capacitor C1; the other end of the microstrip line R1 is connected with the grid of a transistor M, and the other end of the capacitor C1 is earthed; one end of an inductor L2 is connected with a positive voltage, while the other end of the inductor L2 is connected with one end of a microstrip line R2 and one end of a capacitor C2; the other endof the microstrip line R2 is connected with the source of the transistor M; the other end of the capacitor C2 is earthed. One end of an input matching network is connected with the grid of the transistor M; the other end of the input matching network is connected with one end of a capacitor C3; the other end of the capacitor C3 is connected with a 50-Ohm port impedance Z1 to serve as a signal input end. According to the dual-passband power amplifier integrated with the filter, a dual-passband filter is integrated at the output stage of the transistor via an integrating thought, so that a dual-passband output circuit integrated with matching and filtering functions is acquired, meanwhile, the matching circuit can be omitted, so that the amplifier can be directly connected with the filter, and meanwhile the matching function is completed.

The invention discloses a three-passband micro-band filter with low loss, based on a wedged SIR (Signal to Interference Ratio) structure. The three-passband micro-band filter adopts a coupling feedback structure on a micro-band transmission line with matched 50ohm resistance, and a rectangular defective geo-structure (DGS) is additionally arranged under the lower side of the three-passband micro-band filter; and a resonator adopts an interdigital wedged SIR (Signal to Interference Ratio) structure. The wedged SIR structure adopts a transition line for improving the resistance mutation of the SIR to achieve the smooth effect, and can be equivalent to a limiting form of a multi-order SIR at the same time, and the coupling effect is stronger. The rectangular defective geo-structure (DGS) additionally arranged under 50ohm of a coupling feeder line is equivalent to that one low-pass filter is cascaded at the front end of a post-stage band-pass filter, thereby the performance of the filter under the condition of not increasing the volume of the filter is further optimized. The invention discloses the three-passband micro-band filter with the low loss on the basis of the wedged SIR structure, the structure of the which is smaller than that of a single filter, and the three-passband micro-band filter can better meet the requirement on modern communication of miniaturized three-passband.

A realization method of a multiple passband filter that equalizes a group delay without using an external equalizer is disclosed. The realization method includes the steps of: a) calculating a transfer function based on poles and zeros; b) extracting an input/output coupling coefficient and a coupling matrix from the calculated transfer function as a network parameter; and c) physically designing and realizing elements of the filter to have the extracted network parameter.