55 results about "Monopulse antennas" patented technology

A precision-guided hypersonic projectile weapon system. The inventive system includes a first subsystem for determining a target location and providing data with respect thereto. A second subsystem calculates trajectory to the target based on the data. The projectile is then launched and guided in flight along the trajectory to the target. In the illustrative application, the projectile is a tungsten rod and the first subsystem includes a forward-looking infrared imaging system and a laser range finder. The second subsystem includes a fire control system. The fire control system includes an optional inertial measurement unit and predicts target location. The projectile is mounted in a missile launched from a platform such as a vehicle. After an initial burn, the missile launches the projectile while in flight to the target. The missile is implemented with a rocket with a guidance system and a propulsion system. In accordance with the present teachings, the guidance system includes a transceiver system mounted on the projectile. The transceiver system includes a low-power continuous wave, millimeter wavelength wave emitter. A system is included at the launch platform for communicating with the projectile. The platform system sends a blinking command to the projectile and measures the round trip delay thereof to ascertain the range of the projectile. Velocity is determined by conventional Doppler techniques or differentiation. Azimuth and elevation are then determined by a monopulse antenna on the launch platform. As a consequence, the platform ascertains the location of the projectile and the impact point thereof. The platform generates a command to the projectile which is received by the projectile and used to actuate control surfaces to adjust the trajectory and impact point thereof as necessary.

A method and apparatus for electronically steering a RADAR beam across an array of feed horns by moving the phase center of the beam to different origination points on the array—each origination point being the phase center of a feed horn pair. Variations include polarized beams, polarized feed horns, dual-beam systems, dual direction steering, diagonal steering, and cross-polarized wire grids to control beamwidth.

An invention is provided for determining the azimuth pointing angle of a moving monopulse antenna. Pulses of energy are broadcast at the surface of a planetary body. Reflected signals are received from the surface of the planetary body using a plurality of feeds. A monopulse ratio is then calculated based on a sum pattern and a difference pattern. The sum pattern is based on the sum of the reflected signals received using the feeds, and the difference pattern is based on a difference of the reflected signals received using the feeds. An azimuth pointing angle of a monopulse antenna is then calculated using the monopulse ratio.

Detection of moving targets in SAR images is improved by a radar on a moving platform for generating a focused synthetic aperture image of a scene The scene contains a target described by pixels within the SAR image. The radar has a monopulse antenna having a sum channel output and a difference channel output feeding analog to digital converters for converting the sum channel output and difference channel output into respective digital streams concurrently. The digital streams generate a difference channel SAR image and a sum channel SAR image.Target ratios are computed for those pixels descriptive of a target within the scene. Background ratios are computed for pixels around the target. Target ratios and background ratios define respective least square fit of angle discriminants. Comparing the target least square fit of angle discriminant with the background least square fit angle discriminant identifies an angle offset and a Doppler offset of the target with respect to the background.The background least square fit of angle discriminant using background ratios is computed for a region around the target. A 20 by 20 sum synthetic aperture pixels is evaluated as a background around the target.

The invention provides a monopulse antenna angle simulation tracking method, which aims at providing an environment for inspecting and simulating equipment tracking performance at any time to a shooting range monitor system. The method is characterized by comprising the following steps of: establishing an XOY plane measurement coordinate system by taking the center of three axes of an antenna as an original point; constructing a simulation circuit according to an antenna pattern simplified model; drawing four calibration curves of a sum and different signal magnitude difference-deviation angle relationship, sum and difference signal amplitude different-error voltage relationship, deviation angle-error voltage relationship and deviation angle-AGC (automatic gain control) voltage relationship on each angle beyond the main beam of the antenna, and establishing a data mapping table; acquiring the controlled variable of an angle deviation control circuit and simulating to generate a radio frequency tracking signal according to a method of checking a signal amplitude mapping table; and demodulating and extracting an angle error signal by receiving link amplification and down-conversion in an intermediate frequency tracking receiver; and feeding position and pitch angle error voltage to an antenna control unit to complete angle closed-ring tracking.

A mainlobe detection process can include a number of tests that are performed to define when the monopulse antenna system will transition from open loop scanning to closed loop scanning and then to tracking. A hybrid tracking technique is also provided which adaptively discovers and corrects for phase alignment error. Magnitude-only tracking can be performed initially to locate the nulls in the azimuth and elevation ratios and to identify the magnitudes of these ratios at these nulls. Phase tracking can be then performed. During phase tracking, phase corrections can be repeatedly applied to the azimuth and elevation difference channels to correct any phase error that may exist. During this process, the magnitudes of the ratios can be used to determine how the phase corrections should be adjusted. Once the hybrid tracking process is complete, the monopulse antenna system is properly phase-aligned and phase tracking will be correctly employed.