365 results about "Grating lobe" patented technology

A antenna array (20) includes a plurality of periodic or aperiodic arranged sub-arrays (22). Each sub-array (22) includes a plurality of antenna elements (32) arranged in the form of a spiral (30). The sub-arrays (22) can comprise various spiral shapes to provide the required physical configuration and operational parameters to the antenna array (20). The elements (32) of each sub-array (22) are arranged to minimize the number of such elements (32) that intersect imaginary planes perpendicular to the spiral and passing through the spiral center. Such an orientation of the elements (32) minimizes grating lobes in the antenna pattern.

Digital beamforming is provided for use with electronically scanned radar. In an aspect, the present invention provides enhanced sensitivity, wide angle or field of view (FOV) coverage with narrow beams, minimized number of receivers, reduced sidelobes, eliminated grating lobes and beam compensation for target motion. In an aspect, the present invention employs a uniform overlapped subarray feed network, a time multiplexed switch matrix, and a restructured digital signal processor. Antenna channels share a receiver, rather than maintain a dedicated receiver for each antenna element, as in conventional systems. In an aspect, Doppler/frequency filtering is performed on each antenna element or subarray output prior to digital beamforming. Further, Doppler compensation is employed following Doppler/frequency filtering, followed by digital beamforming.

A multi-band wide-angle scan phased array antenna with novel grating lobe suppression has a first plurality of radiation elements for radiating a first frequency arranged in a rectangular configuration. A second plurality of radiation elements for radiating second frequency are arranged in a rectangular frame around the first radiation elements. A third plurality of radiation elements for radiating third frequency are arranged in a rectangular frame around the second radiation elements. The radiation elements are apertures that are λ/2 of an operating frequency in size. The radiation elements may also be arranged in square, circular, or elliptical configurations.

A multiple input multiple output (MIMO) antenna for a radar system that includes a first transmit antenna, a second transmit antenna, and a receive antenna. The first transmit antenna is configured to emit a first radar signal toward a target. The first transmit antenna is formed of a first vertical array of radiator elements. The second transmit antenna is configured to emit a second radar signal toward the target. The second transmit antenna is formed of a second vertical array of radiator elements distinct from the first vertical array. The receive antenna is configured to detect radar signals reflected by a target toward the receive antenna. The receive antenna is formed of a plurality of paired vertical arrays of detector elements.

The present invention relates to a vehicle mountable satellite antenna as defined in the claims which is operable while the vehicle is in motion. The satellite antenna of the present invention can be installed on top of (or embedded into) the roof of a vehicle. The antenna is capable of providing high gain and a narrow antenna beam for aiming at a satellite direction and enabling broadband communication to vehicle. The present invention provides a vehicle mounted satellite antenna which has low axial ratio, high efficiency and has low grating lobes gain. The vehicle mounted satellite antenna of the present invention provides two simultaneous polarization states. In one embodiment, an inverted L-shaped waveguide has a first wall extending vertically downward from a top surface. The top surface can include a ridge portion. The top surface includes a plurality of radiating elements for forming a radiating surface.

Certain embodiments include a system and method for improved compound imaging using a plurality of imaging modes. In an embodiment, a plurality of echo signals are received in response to a plurality of beams formed based on different imaging modes corresponding to different steering angles, such as steered or non-steered angles. The plurality of echo signals is compounded to form a compound image. In an embodiment, the imaging mode includes at least one of harmonic, fundamental, coded harmonic, and variable frequency imaging. Parameters may be generated for the plurality of beams formed based on different imaging modes corresponding to different steering angles. Additionally, the parameters may be stored. The echo signals may be filtered. Imaging mode may be controlled based on steering angle. Employing different imaging modes based on steering angles for spatial compound imaging helps reduce grating lobe artifacts while improving speckle reduction effect.

A system and method for medical treatment of tissue using ultrasound. The system comprises a probe having an array of transducer elements, an ultrasound waveform generator adapted to generate at least one electrical ultrasound signal, and a plurality of phase controls, each coupled to the ultrasound waveform generator and adapted to generate from the electrical ultrasound signal a phase-shifted drive signal that is coupled to an associated transducer element. The drive signal is effective to control grating lobe foci emitted by the array. The method employs the system.

The invention provides an ultrasonic transmit-receive apparatus which solves a false image problem caused by grating lobes and side lobes and offers high bearing resolution without increasing in the scale of hardware or in manufacturing cost. Using a transducer having multiple transducer elements arranged on a surface of the transducer along its circumferential direction, the apparatus emits ultrasonic waves in directionally varying frequency bands and receives echo signals from specified angular directions while selecting the frequency from one direction to another. In a Doppler transmission method, for example, the apparatus drives the individual transducer elements in such a manner that the ultrasonic waves emitted by the transducer elements are equivalent to ultrasonic waves emitted from an imaginary moving sound source moving within a circle enclosed by the multiple transducer elements arranged along the circumferential direction, so that the transducer elements emit ultrasonic signals at directionally varying Doppler shift frequencies.

A method of suppressing grating lobes generated in a radiating pattern of a phased array antenna, and a patch antenna element for use in the phased array antenna are described. The phased array antenna is formed from a plurality of symmetrical patch antenna elements spaced apart at a predetermined distance from each other. Each patch antenna element is configured for producing an asymmetrical radiation pattern. The antenna element includes a conductive ground plane, a radiating patch backed by a cavity and arranged in cavity aperture, and a feed arrangement. The patch antenna element is configured such that a dimension of the radiating patch along the E-plane of the antenna element is less than the dimension of the cavity aperture by a first predetermined value selected to provide an asymmetrical radiation pattern of the patch antenna element. To provide a required degree of the asymmetry of said radiation pattern, a dimension of the radiating patch along the H-plane should be less than the dimension of the cavity aperture along said H-plane by a second predetermined value.

The invention relates to a high power microwave radial line slit array antenna which comprises a coaxial input waveguide, a radial line leaky wave waveguide and an antenna housing, wherein an output port of the coaxial input waveguide is connected with an input port of the radial line leaky wave waveguide, and an output port of the radial line leaky wave waveguide is sealed through the antenna housing. Microwaves are inputted through a coaxial over-mode waveguide in a transverse electronic and magnetic (TEM) mode, folding conversion is carried out through a double layer radial line waveguide, and microwave radial inner feedback is achieved on a waveguide upper layer. Slit unit arrays arranged on an antenna aperture cut a radial electric field, distant field same-phase superimposed circular polarization radian is achieved, the whole axial dimension is small, and the structure is compact. Due to action of a radial line slow wave structure, the wavelength of the radial line waveguide is reduced, and generation of slit array grating lobes is restrained. Due to the fact that a high order reflection mode excited by a wide slit array is restrained through a reflection offset spiral groove in a lower layer waveguide, the whole antenna has high radiant efficiency. Due to the improvement on the slit unit structure and vacuum sealing of the antenna housing, the whole radiating system has high power capacity, and application requirements in the high power microwave field can be met.

The invention relates to a double-frequency double-circular polarization common-caliber antenna array for two-dimensional phase control scanning, wherein the antenna array covers a Ka-frequency range and a Ku-frequency range. At the overlapping portion of the two frequency ranges, a basic composition unit of the antenna array is formed by encircling of eight Ka-frequency range metal radiation sheets around one Ku-frequency range metal radiation sheet. At the edge portion, intervals of Ku-frequency range metal radiation sheet need to be adjusted to form an array with a compact layout, thereby effectively reducing a minor lobe and inhibiting a grating lobe. And antennas with different frequency ranges use metal radiation sheets with different polarization modes to form a double-circular polarization state, thereby improving the polarization isolation of the common-caliber antennas. According to the invention, on the basis of the reasonable layout, the antennas with the Ka-frequency range and the Ku-frequency range can be integrated into one caliber; and the mutual influence is minimized by using the means of array optimization and polarization isolation and the like. The antenna array is suitable for various two-dimensional phase control array antenna systems with low-profile requirement and compact structure and two-dimensional phase scanning with the large scanning angle can be realized.

The present invention relates to a vehicle mountable satellite antenna as defined in the claims which is operable while the vehicle is in motion. The satellite antenna of the present invention can be installed on top of (or embedded into) the roof of a vehicle. The antenna is capable of providing high gain and a narrow antenna beam for aiming at a satellite direction and enabling broadband communication to vehicle. The present invention provides a vehicle mounted satellite antenna which has low axial ratio, high efficiency and has low grating lobes gain. The vehicle mounted satellite antenna of the present invention provides two simultaneous polarization states. In one embodiment, a hybrid mechanic and electronic steering approach provides a more reasonable cost and performance trade-off. The antenna aiming in the elevation direction is achieved via control of an electronic beamforming network. The antenna is mounted on a rotatable platform under mechanical steering and motion control for aiming the antenna in the azimuth direction. Such approach significantly reduces the complexity and increases the reliability of the mechanical design. The antenna height is compatible to the two-dimensional electronic steering phased-array antenna. Additionally, the number of the electronic processing elements required is considerably reduced from that of the conventional two-dimensional electronic steering phased-array antenna, thereby allowing for low cost and large volume commercial production. The present invention provides electronically generated left, right, up, and down beams for focusing the antenna beam toward the satellite while the vehicle is moving. All of the beams are simultaneously available for use in the motion beam tracking. This provides much faster response and less signal degradation.

The invention discloses a double frequency dual polarization wide angle scanning co-aperture phased array antenna. The antenna comprises a low frequency antenna unit and a high frequency antenna unit;the high and low frequency antennas respectively work in different work modes, a radiation aperture of each low frequency antenna unit and a sub array of the high frequency antenna are conformal, sothe finally acquired co-aperture array can realize double frequency bands, dual polarization and wide angle scanning; the low frequency antenna is a connection chamber antenna, a metal floor is with achamber, for avoiding influence of height inconsistency of the metal floor on work performance of the high frequency antenna, a reflection surface employs a selection surface with resistance frequency when the high and low frequency antennas are conformal; feed of the two-frequency band antennas are in common ground to the metal floor, feed ground connection of the high frequency antenna can be direct connection or direct communication with the metal floor through a capacitor, a resistor and an inductor. The antenna is advantaged in that double frequency dual polarization can be realized in aco-aperture antenna form, wide angle scanning can be realized without grating lobe, the structure is simple, and the antenna is easy to process and assemble.

The invention provides a sparse array broadband beamforming grating lobe suppressing method. The method comprises a step 1 of performing frequency-domain broadband beamforming on array signals received by multiple array elements of a sparse array; a step 2 of predicting a grating lobe angle by using the orientation [theta]k of a strong interference target signal obtained in the step 1; a step 3 of resolving the start-stop range of the grating lobe of each frequency point according to the grating lobe angle [theta]kfj obtained in the step 2 and the main lobe width of each frequency point; a step 4 of computing a grating lobe suppression weight coefficient matrix Wk according to a grating lobe range obtained in the step 3; and a step 5 of suppressing the gratin lobe by using the grating lobe suppression weight coefficient matrix Wk obtained in the step 4 and a spatial spectrum output matrix P of each frequency point obtained in the step 1; and a step 6 of adding the spatial spectrum output matrix Pout after the grating lobe suppression in order to perform broadband spatial spectrum synthesis. The method solves broadband beamforming grating lobe influences caused by a common equal-interval sparse array and is used in signal processing field.

Grating lobe free scanning in a phased array with sparse element spacing is obtained by restricting the maximum scan angle for elements in the array, and cladding the array. Array elements may be integrated into the cladding.

The invention belongs to a method for processing uniform ultra-sparse array antenna beam pointing fuzziness in the radar technology. The method comprises the steps of; performing initialization processing; performing directional transmission and reception by a first main lobe according to the set reference working frequency and two associated working frequency and pulse number in turn and performing comprehensive processing on the acquired three groups of target information so as to determine the existence of the target and removing pointing fuzziness caused by a grating lobe; when the target exists, inputting the angle and distance, speed and magnitude value of the target into a radar data processor together; and then repeatedly performing the processing on other main lobes so as to finish detection of the target on the pointing position of each main lobe. In the method, the angle range without grating lobe fuzziness is two times wider than that of two pieces of background technology and the array element number is reduced by over 50 percent, so that the method for the suppressing the uniform ultra-sparse array antenna beam pointing fuzziness is characterized in that: adverse impact of the grating lobe on the radar measured angle can be removed to the full extent; the antenna array element number and corresponding channel number of large-aperture uniform array radar are effectively reduced; the system cost is reduced, the application range is enlarged, and the like.