What Is a Monopulse Radar?

Monopulse radar is a precision tracking radar. Each pulse it emits, the antenna can form several beams at the same time, and compare the amplitude and phase of the echo signals of each beam. When the target is located on the antenna axis, the amplitude and phase of the echo signals of each beam are equal, and the signal difference is zero. ; When the target is not on the axis of the antenna, the amplitude and phase of the echo signals of the beams are different, resulting in a signal difference. The antenna is driven to turn toward the target until the antenna axis is aligned with the target. The sum of the signals received by each beam can measure the distance of the target, thereby achieving the measurement and tracking of the target.

Monopulse radar is a precision tracking radar. Each pulse it emits, the antenna can form several beams at the same time, and compare the amplitude and phase of the echo signals of each beam. When the target is located on the antenna axis, the amplitude and phase of the echo signals of each beam are equal, and the signal difference is zero. ; When the target is not on the axis of the antenna, the amplitude and phase of the echo signals of the beams are different, resulting in a signal difference. The sum of the signals received by each beam can measure the distance of the target, thereby achieving the measurement and tracking of the target.

The monopulse radar currently used has basically achieved modularization, serialization and generalization, and has the characteristics of multi-target tracking, moving target display, fault self-check, and convenient maintenance.

Chinese name

Monopulse radar

Foreign name

monopulseradar

Types of

Precision tracking radar

Classification

Two categories

(Monopulseradar)

Monopulse radar usually has two categories: amplitude comparison monopulse radar and phase comparison monopulse radar. It has higher angular accuracy, resolution and data rate, but the equipment is more complicated. Monopulse radar has been widely used as far back as the 1960s. The U.S., British, French, and Japanese armed forces are heavily equipped with monopulse radars, which are mainly used for target identification, precision tracking and measurement of shooting ranges, early warning and tracking of ballistic missiles, missile reentry ballistics measurement, rocket and satellite tracking, weapon fire control, and gun positions. Reconnaissance, terrain following, navigation, map mapping, etc .; it is mainly used for traffic control in civil use. The monopulse radar currently used has basically achieved modularization, serialization and generalization, and has the characteristics of multi-target tracking, moving target display, fault self-check, and convenient maintenance.

Monopulse radar related introduction

Monopulse radar is a tracking radar that can obtain all the angular coordinate information of a target from a single echo pulse signal. According to different methods of extracting angular error information, it is divided into two types: amplitude comparison monopulse radar and phase comparison monopulse radar.

Monopulse Radar Amplitude Comparison

The angle measurement system of amplitude comparison monopulse radar usually consists of four antenna feeding units and three receiving branches. When transmitting radio frequency pulses, the four antenna feed units combine into a transmit beam. When receiving the echo signal, the four antenna feeding units form five receiving beams through the radio frequency and the differential bridge junction network. One of them is a sum beam, which is formed by adding all the received signals of the four antenna feeding units, and the center axis is the aiming axis of the antenna. The received signal of the and beam is amplified and detected by the and branch receiver to provide information such as the distance and speed of the target. The two beams on the same horizontal plane are azimuth angle beams, which have the same shape, are arranged symmetrically to the left and right, and overlap at a certain angle.

The other two are elevation angle measuring beams, which are on the same vertical plane (perpendicular to the azimuth beam) and also have the same shape. They are arranged symmetrically up and down with the aiming axis and overlap at a certain angle. The signals received by the two azimuth beams are subtracted from each other via the sum difference bridge junction network to obtain an azimuth difference signal. When the antenna aiming axis is aligned with the target, the amplitudes of the signals received by the two azimuth beams are the same, and the difference signal is zero. When the target deviates from the antenna sight axis in azimuth, the amplitudes of the signals received by the two azimuth beams are different, and an amplitude difference signal is output, which is called an azimuth difference signal.

This difference signal is amplified by the azimuth difference branch receiver and multiplied with the branch signal in the phase detector to generate an azimuth error signal. The magnitude of the error signal is proportional to the angle of the target from the rotation axis, and the polarity is determined by the direction of deviation. . The error signal is sent to the antenna control system, which drives the antenna to rotate in the direction of reducing the azimuth error signal until the aiming axis is aligned with the target. When the azimuth error signal is zero, the antenna stops rotating, so that the antenna accurately tracks the target in azimuth. The operation of the two elevation beams and the elevation difference receiving branch is similar to that of the azimuth difference branch.

Monopulse radar phase comparison

Phase comparison monopulse radar uses two identical and slightly separated antennas on each of the horizontal and vertical planes. On the horizontal plane, the two azimuth angle beams have the same shape, and the beam axis (the strongest radiation direction of the beam) is aimed at the antenna at a certain interval. The axes are arranged parallel and symmetrical. The angle formed by the target in the far-field region and the two-beam axis is almost equal, so the amplitude of the received echo signal is also equal. When the target is located on the antenna's aiming axis in azimuth, the echo signals received by the two beams have the same phase, and the difference signal is zero.

When the target deviates from the antenna aiming axis in azimuth, because the two antennas are separated by a distance, the echo signals received by the two antennas are different in phase due to the existence of a wave path difference, resulting in a phase difference. The phase error detector detects the azimuth error signal. To drive the antenna to accurately track the target in azimuth. The operation of the elevation branch is similar to that of the azimuth branch.

- Monopulse Radar Monopulse Radar-Development Status

Compared with conical scanning radar, monopulse radar has high angular accuracy, fast speed, and strong anti-angle deception interference ability. Since its successful development in the late 1940s, it has been widely used in fire control, precision measurement and weather radar. Monopulse angle measurement technology is also widely used in three-coordinate radar and phased array radar. ^[1]