52results about How to "Good frequency selection characteristics" patented technology

The invention relates to a high/intermediate-frequency front-end circuit of a digital short-wave receiver, which mainly comprises a PIN diode electric control attenuator, digital control electric tuning preselected tracking filter groups, a gain control low-noise amplifier, a direct digital frequency synthesizer, a plurality of frequency mixers, an intermediate-frequency amplifier, an amplitude detection and grain control circuit and a preselected controller, wherein a weak signal sensed by an antenna is subjected to tracking frequency selection by the first digital control electric tuning preselected tracking filter group after passing through the PIN diode electric control attenuator and then is subjected to frequency selection by the second digital control electric tuning preselected tracking filter group after being amplified by the gain control low-noise amplifier, the signal after being subjected to frequency selection is subjected to frequency mixing three times with the plurality of frequency mixers by three local oscillators formed by the frequency synthesizer and is transmitted to a demodulator for demodulation after being subjected to multistep intermediate-frequency amplification and gain control processing. The high/intermediate-frequency front-end circuit of the digital short-wave receiver can meet the requirement of high sensitivity, strong anti-interference performance and wide dynamic range for the short-wave receiver, is suitable for a frequency-hopping receiving machine with rapid frequency change and has the effects of low insertion loss, low in-band ripple and high selectivity.

A stacked cascaded two cavity substrate integrated waveguide dual mode bandpass filter comprises two substrate integrated waveguide resonant cavities arranged up and down through stacked cascaded, a belt-type line connecting the two resonant cavities, a microstrip line serving as input and output of the filter and a coupling probe. The filter has the advantages that size is small, manufacture and machining are facilitated, performances are excellent, and the requirements on a radio frequency filter by a modern wireless communication system are met.

The invention belongs to the technical field of spatial filtering, and particularly relates to a three-way bandwidth frequency band frequency selecting surface structure and an antenna cover. The antenna cover can serve as the antenna cover of a multi-frequency antenna of communication systems, such as radar and a satellite. The three-way bandwidth frequency band frequency selecting surface structure comprises a layer medium substrate, and two layers of same frequency selecting surfaces which are positioned on the upper side and the lower side of the layer medium substrate, wherein each frequency selecting surface consists of patch units which are arranged periodically; each patch unit comprises a square patch of which the four sides are cut into notches; the notches are rectangular openings, are positioned on the axes of the square, are in two-to-two correspondence and are not communicated with one another; a rectangular wave-shaped metal line extends from each rectangular opening; each metal line is connected with the metal lines of adjacent patch units on the periphery; the metal lines are positioned on the two symmetry axes of the square. The antenna cover is mounted out of an antenna or an antenna array; an electromagnetic valve incident plane of the antenna cover is formed by the three-way bandwidth frequency band frequency selecting surface structure.

The invention belongs to the technical field of spatial filtering and discloses a light-controlled polarization reconfigurable frequency selective surface unit structure and a radar communication radome. The light-controlled polarization reconfigurable frequency selective surface unit structure comprises an intermediate three-layer dielectric substrate, two layers of patches with different structures on the upper and lower sides of the dielectric substrate, two light-controlled microwave switches on a lower layer patch, and a metal pillar which is connected to the upper and lower layer patchesand passes through the dielectric substrate, wherein an I-shaped slit is formed at the right side of a metal layer according to an upper layer patch structure, two mutual perpendicular T-shaped slitsare formed in the metal layer, two light-controlled microwave switches are loaded to the two T-shaped slits, and the ON and OFF of the light-controlled microwave switches are controlled by introducing laser with fibers. According to the invention, on one hand, the effect of spatial filtering can be achieved, and on the other hand, the 0-degree and 90-degree polarization reconfigurable functions of the antenna can be achieved.

The invention discloses a filtering patch antenna without additional arrangement of filter circuit, and an adjustment method thereof. The antenna comprises a bottom metal reflection floor, an intermediate feed patch and a top parasitic patch. The two sides of the feed patch are each provided with a short circuit probe, the feed patch is provided with a U-shaped groove, a short circuit probe is arranged in front of an opening of the U-shaped groove, and a feed point is arranged behind a closing position of the U-shaped groove. The top parasitic patch is fixed right above the feed patch at an interval of a certain height. According to the invention, the filtering patch antenna itself has a filtering function and realizes a bandpass filtering characteristic without additional arrangement of the filter circuit. The passband edge is deep, the sideband suppression is obvious, the frequency selectivity is good, adjacent frequency interference can be inhibited, the bandpass filtering characteristic and an antenna radiation function are integrated together, the plat grain at a passband position is quite high, and the filtering patch antenna is applied to such mobile communication scenes as WCDMA, 4G-LTE, WLAN and the like.

According to the invention, three technical characteristics are utilized for reducing the size of a resonance cavity. First, a substrate integrated waveguide in an incomplete mode is adopted. Second, a small-size CRME (Circular Ring Miniaturized Element) is loaded on the surface of the resonance cavity so as to excite resonant frequency of lower orders and thus the size of the resonance cavity can be reduced. Third, a feeding mode based on combination of a coplanar waveguide and the CRME is adopted. According to the invention, the ultra-small filter based on the substrate integrated waveguide in the incomplete mode is low in loss and good in frequency selection properties and the size of the filter can be reduced substantially. By the design of the novel CRME, the out-of-band suppression property of the filter is improved substantially. By the design of a single-layer PCB, processing, integration with other planar circuits and cost reduction are facilitated.

The invention discloses a microwave/millimeter wave substrate integrated waveguide E-surface inductive band filter, comprising a dielectric substrate with double sides provided with metal chips, where the dielectric substrate is provided with an integrated waveguide, which is composed of at least two rows of metallic through holes, one surface of the dielectric substrate is provided with input and output ends respectively connected with two ends of the metal chips, an E-surface inductive band is arranged in the center of the integrated waveguide and of metallic through holes. And it is implemented by traditional PCB or LTC process, beneficial to its integration in the design of a microwave/millimeter wave circuit, simple in structure, and easy to design and low-cost, almost no parasitic radiation and having good frequency selectivity.

The present invention relates to an RFID reader and a signal receiving method thereof. The RFID reader according to one embodiment of the present invention down-converts transmission leakage signals introduced into a reader receiver and then suppresses them through a band stop filter in a low frequency band and up-converts them, thereby making it possible to effectively suppress the transmission leakage signals.

The invention relates to a modified half-mode substrate integrated waveguide inductive band filter comprising a modified half-mode substrate integrated waveguide and inductive metal via holes. The modified half-mode substrate integrated waveguide inductive band filter comprises a dielectric substrate (3), a linear metal belt (4) and a trapezoidal metal belt (51); the linear metal belt (4) and the trapezoidal metal belt (5) are in parallel arrangement on the upper surface of the dielectric substrate (3), a gap (7) is reserved between the two metal belts, an input end (2) and an output end (8) are respectively set at two ends of the trapezoidal metal belt (51); the lower surface of the dielectric substrate is of a lower surface metal patch (52); the linear metal belt (4) is connected with the lower surface metal patch (52) through a row of metal via holes (1) on the liner metal belt (4), the trapezoidal metal belt (51) is connected with the lower surface metal patch (52) through a row of metal via holes (1) on the trapezoidal metal belt (51), and an inductive band (6) consisting of a row of metal via hole arrays is arranged below the trapezoidal metal belt (51). The filter is simple in structure and easy to design.

The invention discloses a microwave photonic filter structure capable of realizing complex coefficient. The structure consists of a laser source (101), a light path sequential connection polarization modulator (102), an optical tunable filter (103), an optical coupler (104), an optical adjustable delay line (105), an optical attenuator (106), a polarization beam splitter (107) and a photoelectric detector (108). The structure has the advantages that the microwave photonic filter has the complex coefficient characteristic; and compared with the negative coefficient filter, the free frequency spectrum range is not changed while the central wavelength of the filter can be adjusted. Compared with the scheme of the conventional complex coefficient microwave photonic filter, the structure can be realized only by one light source, so that the cost is reduced. The tunability of the filter can be realized only by changing the polarization detection direction of an optical signal, so that the adjustment is convenient.

The invention discloses a simplified weighted repeat pseudo-median filtering method with negative coefficients. The method comprises the following steps: taking the frequency response characteristics of an approximation same-order finite impulse response (FIR) filter as an objective, designing weighting coefficients containing negative numbers for weighted pseudo-median computation of filtering window data by an MALLOWS comprehensive method, adjusting the window data by the weighting coefficients; simultaneously, computing weighting coefficients based on the slopes of a group of special structures designed for the filter, computing the overall slope of the window data repeatedly by the weighted pseudo median, carrying out linear transformation on the window data by the slope; and finally carrying out weighted computation on the transformed data by the pseudo-median weighting coefficients to obtain the output value of weighted repeat pseudo-median filtering. The method realizes a better frequency selection characteristic than that of the existing negative coefficient weighted median or pseudo-median filtering method, and simplifies computation in the algorithm to meet the requirement of systems with finite resources, such as a wireless sensor and the like for low power consumption.

The invention discloses a multi-frequency all-metal frequency selection surface unit, which is of an all-metal 3D structure, and the all-metal array structure formed by the periodic arrangement thereof has the band pass characteristic of low Q value in the Ku frequency band, and exhibits the band stop characteristic in the X frequency band and the Ka frequency band. The unit consists mainly of waveguide grid and vibrator structures, The waveguide grid structure constitutes the whole envelope structure of the element and provides the low frequency (X-band) cutoff characteristics of the element.The embedded dipole structure makes the element possess the characteristics of ridge waveguide transmission line and folded resonance, and realizes the band-pass characteristics of Ku band and the band-stop characteristics of Ka band. The waveguide grid and the vibrator structure are directly connected with each other through the central supporting vibrator, which realizes the integration of all-metallization and self-support. The special 3D all-metal structure of the waveguide grid and the vibrator structure realizes the double stopband performance with large frequency span and the frequencyselection performance with wide band-pass characteristics.

The invention discloses a filtering slot antenna with a directional characteristic. The antenna comprises a dielectric substrate, a feed microstrip line is arranged on the top surface of the dielectric substrate, an open slot and a defected ground structure are arranged on the back surface of the dielectric substrate to form a special radiation structure, and the open slot and the defected ground structure are coupled with the feed microstrip line to form a filtering resonance characteristic; and a guide terminal is arranged on the back surface of the dielectric substrate and close to the open slot. According to the slot antenna, the defected ground structure is introduced through the complicated slot, so that the filtering characteristic of the slot antenna and the suppression of an out-of-band signal are realized, the directional characteristic of the filtering slot antenna is realized through the introduction of the guide terminal, and the airspace anti-interference capability is improved. The antenna can be used for arraying and applied to the broadband fields of target detection, target tracking, short-distance wireless communication and the like.

The invention belongs to the technical field of antennas, and discloses a planar horn antenna and filter antenna with a filtering function, which comprises a filtering structure, a radiation structure, a feed structure, a dielectric substrate and a metal floor. The grounding coplanar waveguide is used for feeding a horn antenna, metal floors are arranged on the upper surface and the lower surfaceof the dielectric substrate, the filtering structure is a metallized through hole array embedded in a horn, and finally signals are radiated through the caliber of the horn antenna on the right side.According to the antenna, the horn antenna is printed on a PCB by adopting a planar single-layer structure, the filtering structure is additionally arranged in the horn antenna, the filtering functionis achieved under the condition that the equipment size is not increased, and the antenna is simple and compact in structure and easy to integrate; the antenna works at 16.3 GHz to 17.1 GHz, and hasgood in-band selection and out-of-band rejection characteristics in a frequency band; the defect that a traditional filter antenna is large in design size is overcome, the filter and the antenna are integrally designed, the size is further reduced, the manufacturing cost is low, and the filtering structure is simple in design.

The invention relates to a surface plasmon based waveguide band-stop filter which is composed of a metal film, waveguide tube and a resonant cavity. The waveguide tube is shaped as a long-strip rectangular hole, the resonant cavity is of a square U shape composed of one horizontal extension hole and two vertical extension holes connected to the horizontal extension hole, the shape and size of theone vertical extension hole are completely the same with those of the other, and each of the horizontal and vertical extension holes is shaped as a long-strip rectangular hole of a regular rectangularshape. The filter is simple in structure, small in packaging size, multi-mode, high in transmissivity, smooth in passband, narrower in stop band, high in quality factor and adjustable. The stop bandwidth can be adjusted by changing a structural parameter. It is proved that the stop band transmittance can be lower than 0.01 and the maximal passband transmittance can reach 0.98 with smooth distribution in the top. The filter can be widely applied in micro nano optical integrated devices.

The invention discloses a hairpin type band-pass filter, which comprises an upper metal layer, a dielectric substrate and a lower metal layer which are sequentially stacked, and is characterized in that the upper metal layer and the lower metal layer are connected to form a resonant cavity, the upper metal layer comprises a hairpin type half-wavelength resonator, a first resonator, a second resonator, a third resonator, a fourth resonator and a fifth resonator, the fourth resonator and the fifth resonator are sequentially arranged at intervals, openings of the first resonator, the third resonator and the fifth resonator are arranged upwards, openings of the second resonator and the fourth resonator are arranged downwards, an input microstrip line is connected to an input resonance strip ofthe first resonator, an output microstrip line is connected to an output resonance strip of the fifth resonator, and the input resonance strip and the output resonance strip extend by 1/4 wavelengththrough the microstrip lines in the closed direction of the first resonator and the closed direction of the fifth resonator respectively. The filter can inhibit parasitic passband at a higher frequency outside a passband, realizes wide stop-band characteristic, has good frequency selection characteristic, and is low in insertion loss.

The invention discloses a patch antenna with broadband and filtering characteristics. The patch antenna comprises a metal bottom plate, a dielectric substrate attached to the metal bottom plate, a first resonance unit arranged on the surface of the dielectric substrate and a second resonance unit coupled with the first resonance unit, a radiation patch located above the dielectric substrate, a feed component inner conductor connected with the first resonance unit and penetrating through the dielectric substrate and the metal bottom plate, and a feed component outer conductor disposed on the surface of the metal bottom plate and in communication with the feed component inner conductor. The patch antenna with the broadband and filtering characteristics provided by the invention overcomes theshortcomings and realities of the narrow bandwidth, low gain and poor filtering characteristics of an existing patch antenna, and satisfies the requirements of the antenna wide frequency band, high gain and excellent filtering characteristic in a wireless communication system.

The invention discloses a distributed design method of a non-uniform graph filter bank, which is characterized by comprising the following steps of: 1) designing a non-uniform analysis filter bank; and 2) carrying out distributed reconstruction on the non-uniform graph filter bank. According to the distributed reconstruction method for the non-uniform graph filter bank, the non-uniform graph filter bank with the good frequency selection characteristic and the good sparse characteristic can be obtained, complete reconstruction of the filter bank can be achieved, and meanwhile the method has the high convergence speed and the low calculation cost.

A single-sensor double-frequency output resonant circuit comprises a single sensor and an auxiliary resonant circuit which are connected, wherein the single sensor is formed by connecting a sensor equivalent inductor L and a sensor equivalent resistor R in series; the auxiliary resonant circuit is formed by connecting a resonant inductor L1 and a resonant capacitor C1 in series and then connecting the resonant inductor L1 and the resonant capacitor C1 with a resonant capacitor C2 in parallel. The designing method of parameters of the single-sensor double-frequency output resonant circuit includes the steps that first, the topological structure of the resonant circuit is determined, and then, according to the impedance characteristics of the resonant circuit, a resonance angular frequency equation of the resonant circuit is built, and the resonant circuit parameters are obtained. The single-sensor double-frequency output resonant circuit is simple in structure, all the parameters are designed totally according to deduction of mathematical logical relations without any additionally-added man-made supposed constraint, no computational items are ignored, the parameters are designed strictly, the circuit resonant frequency determined by the parameters is clear and accurate, the energy utilization rate of a double-frequency output induction heating power source is increased, the selectable frequency range of the double-frequency output resonant circuit is also correspondingly widened, and the double-frequency output performance of the resonant circuit is improved.