220results about How to "Reduce sidelobe" patented technology

An antenna system that includes a directional antenna designed to reduce the occurrence of side lobes, thus reducing the possibility of interference with other radio frequencies is disclosed. The directional antenna includes an antenna member and a reflecting tube. The reflective tube is sleeved over the antenna member. The reflective serves to block unwanted radial side lobes. The directional antenna can also include provisions that assist in suspending the antenna member within the reflective tube.

An efficient, low-loss, low sidelobe, high dynamic range phased-array radar antenna system is disclosed that uses metamaterials, which are manmade composite materials having a negative index of refraction, to create a biconcave lens architecture (instead of the aforementioned biconvex lens) for focusing the microwaves transmitted by the antenna. Accordingly, the sidelobes of the antenna are reduced. Attenuation across microstrip transmission lines may be reduced by using low loss transmission lines that are suspended above a ground plane a predetermined distance in a way such they are not in contact with a solid substrate. By suspending the microstrip transmission lines in this manner, dielectric signal loss is reduced significantly, thus resulting in a less-attenuated signal at its destination.

A multibeam antenna for forming multiple beams includes an antenna array and a Butler-matrix feeder circuit. The antenna array is composed of 2.sup.n main antenna elements and a group of 2.sup.n or less auxiliary antenna elements placed at either one or both sides of the main antenna elements. Antenna power is supplied to the antenna array from the Butler-matrix feeder circuit and is distributed to all the antenna elements with higher power to the elements located in the middle of the array and lower power to the elements located at sides of the array. Phase of the power supplied to the main antenna elements is shifted by 180-degree, and the phase-shifted power is distributed to predetermined auxiliary antenna elements. Thus, sidelobes associated with antenna beams are reduced and the beam directivity is improved.

Disclosed is a system and method for a hybrid radar system that integrates frequency-modulated continuous wave (FMCW) mode and interferometry mode. The radar works as a time division system that continuously switches between the FMCW mode and interferometry mode. The FMCW mode is responsible for absolute range detection and the interferometry mode takes cares of the weak physiological movement monitoring. The respective accuracies in range detection and displacement measurement complements the advantages of the two radar modes, providing versatile performance. By steering the antenna beam, the proposed radar system becomes an ideal solution for indoor health care, human localization, and human-computer interaction. Objects or human targets with or without stationary clutters can be precisely located. At the same time, the targets' vital signs and gestures can be monitored.

The invention relates to an array multispectral optical filter and a manufacturing method thereof, belongs to the field of a micro-nano optical filter and solves the problem of integration of multichannel array detection in an existing nanofluidic chip. The optical filter only comprises the following four layers of structures: a two-dimensional metal grating layer, a buffer layer, a waveguide layer and a substrate. The invention also provides the manufacturing method of the optical filter, which utilizes a guided mode resonance principle of a two-dimensional metal grating and implements selection of different wavelengths by regulating the period of the grating. By the thickness of the buffer layer, the half-wave bandwidth of the cut-off wavelength also can be regulated. By regulating a suitable duty cycle of the two-dimensional metal grating layer, side lobes can be reduced. Therefore, relative to other turnable optical filters, the array multispectral optical filter manufactured by the method disclosed by the invention has the outstanding advantages of simple structure, low side lobes, adjustability of the half-wave bandwidth, high transmittance, no relation with polarization and the like. After the optical fiber disclosed by the invention is adopted, the integration of the nanofluidic chip can be implemented.

The low profile antenna assembly comprises a generally rectangular frame member housing a planar antenna. A radar absorbing material is attached to the front side of the housing with a radome covering the front side of the planar antenna and attached to the frame member. The planar antenna is a microstrip array fed by a beam forming network that uses either delay lines or phase shifters to electronically steer the antenna pattern horizontally and vertically. The antenna assembly is weatherproofed, painted and flush mounted against a building surface for camouflaging the antenna assembly from observers at a distance.

A phased array antenna includes an oscillator, a plurality of antenna elements, a phase shifter, a distributor, a receiver, and a control processor. The control processor performs a first calibration process to calibrate a phase of the phase shifter connected to a pair of antenna elements that is selected from the antenna elements and are located at a pair of positions symmetric with respect to a central axis of an array formed by the phased array antenna, and a second calibration process to calibrate a phase of the phase shifter connected to a pair of target antenna elements with respect to a phase of the phase shifter connected to a reference antenna elements located at a central portion of the array. The pair of target antenna elements are located at a pair of positions that are symmetric with respect to the central axis of the array.

The invention discloses an air dielectric cylindrical lens antenna. The air dielectric cylindrical lens antenna comprises a metal disc-shaped parallel plate waveguide, a feed source antenna and arc-shaped metal support plates, wherein the metal disc-shaped parallel plate waveguide comprises an upper metal disc and a lower metal disc, the upper and the lower inner surfaces of the metal disc-shaped parallel plate waveguide are planes or arc-shaped surfaces, a central cavity of the metal disc-shaped parallel plate waveguide forms an air dielectric cylindrical lens, an annular boss is arranged below the edge of the upper disc of the metal disc-shaped parallel plate waveguide, the annular boss is arranged above the edge of the lower disc of the metal disc-shaped parallel plate waveguide, the feed source antenna is arranged between the two annular bosses, the feed source antenna is embedded in an arc-shaped groove between the arc-shaped metal support plates on the edges of the two metal discs, and the arc-shaped metal support plates are connected with the two metal discs through screws. The feed source antenna is a horizontal polarization gradient groove antenna or a horizontal polarization gradient groove antenna array.

A waveguide slotted array antenna comprises a feed layer and a radiation layer, wherein the feed layer is located below the radiation layer, and the radiation layer comprises a first radiation unit, a second radiation unit, a third radiation unit and a fourth radiation unit which are stacked from bottom to top; the first radiation unit comprises a first flat metal plate and a first radiation array arranged on the first flat metal plate, the second radiation unit comprises a second flat metal plate and a second radiation array arranged on the second flat metal plate, the third radiation unit comprises a third flat metal plate and a third radiation array arranged on the third flat metal plate, and the fourth radiation unit comprises a fourth flat metal plate and a fourth radiation array arranged on the fourth flat metal plate. The waveguide slotted array antenna has the advantages of low sidelobes and low cost while ensuring broad bands and high gains, and can be made small.

The invention discloses a coherent laser radar based on pulse coding technology. The invention aims at low signal-to-noise ratio (SNR) of echo signals of coherent laser radars, and proposes a method for improving the signal-to-noise ratio of the system and increasing the dynamic range of the system by using the pulse coding technology. The invention outputs the pulse coding sequence codes by an electro-optic modulator, reduces the time-domain cross-correlation between the respective transmit waveforms, reduces auto-correlated side lobes by using the complementary properties of the Golay complementary sequence, and reduces side lobes after the waveform pulse compression. In addition, the present invention performs decoding according to the decoding rule, solves the problem that the pulse peak power of the fiber laser is limited, significantly improves the signal-to-noise ratio of the coherent laser radar, effectively improves the detection range, and does not require pulse accumulationtime, without sacrificing detection time and distance resolution.

The invention discloses a low-side-lobe beam pattern integrated design method based on convex optimization. Auxiliary variables are introduced to achieve variable separation by adopting an alternative direction multiplier method (ADMM), a large amount of original inequality constraint limits are converted into solvable problems, iteration solution is performed by applying an ADMM thought, and accordingly parameters are determined to obtain an ideal wave beam, namely side-lobe values are reduced. The robustness of a wave beam forming device is good in the process by optimizing wave beam side lobes, the side effect of the side lobes on array gains is low, the obtained side lobe values are low, and the low-side-lobe beam pattern integrated design method is simple and simple in operation and has a very good practical value.

The invention discloses a super-surface lens antenna, and belongs to the technical field of antennas. The antenna consists of a conical-horn antenna and a wave beam focusing super-surface with the sub-wavelength thickness. The wave beam focusing super-surface is formed by a transmission-type linear polarization unit structure array with the parabolic-type cross polarization phase space distribution. The transmission-type linear polarization unit structure sequentially comprises a metal grid, a dielectric substrate, a metal elliptical opening resonant ring, a dielectric substrate and a metal grid from the bottom to the top. The size and period of the transmission-type linear polarization unit structure can change the working frequency band, bandwidth and the focusing efficiency of the wave beam focusing super-surface. According to the invention, the core component, the wave beam focusing super-surface, of the super-surface lens antenna is manufactured through the printed circuit board technology. The super-surface lens antenna is low in construction cost, employs a plane structure, has the sub-wavelength thickness, is light in weight, is small in size, is small in standing-wave ratio, is narrow in beam, is high in gain, and can be designed and implemented at any band.

The invention discloses a submatrix level linear constraint self-adaptive beam forming method based on feature subspaces, and belongs to the technical field of array signal processing. The method includes the steps that eigenvalue decomposition is conducted on a sampling covariance matrix, so that the needed interference subspaces are estimated, then, interference signals are restrained in a self-adaptive mode by the way that interference subspace constraint beam response is zero, a self-adaptive directional diagram is constrained by introducing a penalty function, so that a main lobe achieves shape preserving, and a side lobe is lowered. According to the method, self-adaptive interference restraint is carried out, meanwhile main lobe shape preserving and side lobe lowering of the self-adaptive directional diagram obtained in a submatrix are achieved, and good output SINR performance can be obtained. The method is suitable for submatrix level linear constraint self-adaptive beam forming.

The invention discloses a weighting sparse-driven self-focusing SAR (Synthetic Aperture Radar) imaging method. The method comprises the steps as follows: establishing a linear observing model of echo data and an observing scene to construct the optimized target function; adopting the weighted L1 norm; and then carrying out an L1 norm approximating method to approximate the L1 norm in the target function; iterating and solving the optimized target function; and estimating the phase error of the linear observing model, and modifying the linear observing model to obtain a more accurate observing model, thus achieving the focusing of the synthetic aperture radar (SAR) image. Compared with the synthetic aperture radar (SAR) image reconstructed via a traditional focusing method (such as PGA (Programmable Gain Amplifier) and a sparse-driven auto-focusing (SDA), the synthetic aperture radar image obtained via the method provided by the invention is lower in sidelobe, and has a better effect on focusing.

The feed source of the corrugated horn comprises a harmful harmonic mode suppresser, the corrugation groove mode converter with double-groove structure, the frequency change and angle change transition section with double-groove deep corrugation structure and the radiation section with double-groove deep corrugation structure. The corrugation groove mode converter combines the harmful harmonic suppresser and the annular loading groove as well as the straight groove so as to reach the purpose of restraining excitation of the harmful harmonic mode, lowering reflectino loss and dual-band joint use. The invention possesses the features of rotation symmetry of the radiation pattern in two discrete frequency ranges, low electrical level of the side lobe and cross polarization, low reflection loss and high gain.

The invention relates to a self-adaptive acoustic imaging method. The method includes the steps that acoustic wave signals are received after being transmitted at fixed focuses through an acoustic transducer array; focusing beamforming processing is carried out on the acoustic wave signals received by each array element in the acoustic transducer array to obtain acoustic radio frequency scanning line data; the focuses are used as virtual sources in synthetic aperture processing, tine delay from each virtual source to the spatial point is calculated by means of a cylindrical wave propagation model, and spatial point-by-point focusing is carried out on the scanning line data; self-adaptive weighting is conducted on the result of the spatial point-by-point focusing by the adoption of correlation coefficients or generalized correlation coefficients, the proportion of coherent components is increased, and the proportion of incoherent component is reduced; image transformation is carried out on all the scanning line data after self-adaptive weighting conducted on the result of the spatial point-by-point focusing to obtain images. According to the method, the lateral resolution and contrast ratio which are identical in depth are achieved, the number of sidelobes is effectively reduced, and therefore all-round improvement in acoustic imaging quality is achieved.

A sampled analog beamformer for ultrasound beamforming includes an array of transducers for transmitting analog signals and receiving reflected analog signals, and a sampled analog filter for filtering the received reflected analog. The sampled analog filter includes a delay line for adding a delay to each of the received reflected analog signals. Using a sampled analog filter in an ultrasound beamforming system reduces the power usage of the system and decreases the number of components in the system.

The invention discloses a coaxial S/X dual-frequency sharing feed source network. The coaxial S/X dual-frequency sharing feed source network comprises a coaxial horn feed source, wherein the coaxial horn feed source is composed of an S-frequency-band horn and an X-frequency-band horn, the S-frequency-band horn is externally connected with an S-frequency-band feed network, and the X-frequency-band horn is externally connected with an X-frequency-band feed network, arranged in the S-frequency-band horn in a sleeved mode and coaxial with the S-frequency-band horn. Four transmission arms distributed in the form of a cross and used for achieving S-frequency-band signal wave separating are arranged at the bottom of the S-frequency-band horn, and inner cavities of the four transmission arms are communicated with the inner cavity of the S-frequency-band horn. The coaxial S/X dual-frequency sharing feed source network achieves S-frequency-band single-pulse tracking and circular polarization signal receiving and sending and X-frequency-band single-pulse tracking and circular polarization signal receiving, has the advantages of being wide in working band, small in standing wave, large in power capacity, small in consumption, low in sidelobe, good in directional diagram equalization, small in axial ratio and the like and is suitable for a double-reflection-face multi-frequency multi-tracking-satellite communication and control antenna with the length larger than 7.3 m.

The invention discloses an omni-directional side lobe suppression method for synthetic aperture radar imaging processing. The method comprises the following steps of: arranging two-dimensional echo signals obtained by synthetic aperture radar into one-dimensional data; determining an imaging plane region position; constructing into a measuring matrix corresponding to an imaging plane; and finally, processing the one-dimensional echo data by using a linear least square method in combination with a measuring matrix, thereby realizing omni-directional side lobe suppression of a synthetic aperture radar imaging result and obviously reducing the energy leakage. Thus, the energy leakage of the imaging result of the processed satellite-borne echo data is the minimum, and further, the aim of suppressing side lobe is fulfilled. The omni-directional side lobe suppression method has no special requirement on target scattering intensity, can be used for imaging processing of any scene target and has a wide application range.