Two-channel monopulse radar for three-dimensional detection
View Patent ↗An apparatus for determining the position of a target object using a two-channel monopulse radar. The radar may include two transmitting antennas and one common receiving antenna disposed in a coplanar arrangement. The transmitting antennas may be positioned on the focal plane of the radar along a focal plane axis that extends through, and that is perpendicular with, a boresight axis of the radar. The transmitting antennas may be spaced apart from one another in a first dimension a distance equal to about one half of one wavelength of the radar's center operating frequency. One of the transmitting antennas may be squinted at an angle of θ 1 relative to the boresight axis and the other transmitting antenna may be squinted at an angle of θ 2 relative to the boresight axis in a second dimension. The transmitting antennas are not squinted relative to one another in the first dimension.
1. A method for acquiring position data for a target object using a two-channel monopulse radar, the method comprising:
transmitting a first signal from a first transmitting antenna squinted in a first direction at a first angle relative to a boresight axis of the radar, the boresight axis of the radar being perpendicular to a focal plane axis of the radar;
transmitting a second signal from a second transmitting antenna squinted in a second direction at a second angle relative to the boresight axis of the radar;
receiving the first and second signals after they have been reflected;
mixing, sampling and holding, integrating, and analog-to-digital converting the received reflected first and second signals;
repeating the steps of transmitting, receiving, mixing, sampling and holding, integrating and analog-to-digital converting until datasets are generated for the first and second transmitting antennas;
using the datasets, calculating one of an elevation angle and an azimuth angle from an amplitude ratio of the first and second received signals; and
using the datasets, calculating the other of the elevation angle and the azimuth angle from a phase difference between the first and second received signals.
2. The method of claim 1 , wherein the focal plane axis is horizontally oriented.
3. The method of claim 1 , wherein the focal plane axis is vertically oriented.
4. The method of claim 1 , further comprising
spacing the first transmitting antenna and the second transmitting antenna apart from one another along the focal plane axis of the radar a distance equal to about one half of one wavelength of a center operating frequency of the radar.
5. The method of claim 1 , wherein the first angle relative to the boresight axis of the radar is not equal to the second angle relative to the boresight axis of the radar.
6. The method of claim 1 , further comprising coherently combining the datasets for the first and second transmitting antennas to generate a combined dataset.
7. The method of claim 6 , further comprising:
converting the combined dataset to acquire a range of a target object when the combined dataset is a Doppler-only dataset; and
converting the combined data set to a magnitude array when the combined dataset is not a Doppler-only dataset.
8. The method of claim 7 , further comprising:
when a target object has been detected:
calculating one of an elevation angle and an azimuth angle of the target object from an amplitude ratio of the first and second received signals; and
calculating the other of the elevation angle and the azimuth angle of the target from a phase difference between the first and second received signals.
9. The method of claim 8 , further comprising reporting position data of the target object to a master control.