Название: Wideband Radar
Автор: Teng Long, Yang Li, Weifeng Zhang, Quanhua Liu
Издательство: Springer/National Defense Industry Press
Год: 2022
Страниц: 200
Язык: английский
Формат: pdf (true), epub
Размер: 43.2 MB

Wideband Radar focuses on system theories and signal processing techniques for wideband radar systems. Author Professor Teng Long and his fellows present a comprehensive introduction to the fundamental theory, latest technology developments in signal processing and recent progresses in civil applications of wideband radar. Each chapter begins with an introduction describing what a reader will find in that chapter. The book is addressed to all scientists, whether at universities or in industry, who wish to keep abreast of the important advances in wideband radar. We look forward to further excitement ahead and new developments in wideband radar, and we hope to share them with you, our esteemed readers.

Phased array radar, known as electronic scanning radar, can control the beam pointing in the electronic way. Compared with mechanically scanning radars, phased array radars have a fast beam switching, and can simultaneously fulfill the search, detection and tracking of multiple targets in different directions and at different heights. Phased array radar systems have dense antenna array elements, each of which have its own transmitter. Therefore, the whole system holds the potential for high power-aperture products. Switching of phased array beams can be realized with the use of phase or frequency scanning array. Compared with mechanical scanning radar, phased array radar has several outstanding advantages including multiple functions, strong maneuverability, short response time, high data rate, strong anti-jamming, and high reliability.

The remarkable feature of wideband radar is its high range resolution, which is the inverse of the signal bandwidth. It is generally considered that the bandwidths of wideband and narrowband signals are relative, and there is no uniform and strict definition on wideband signals. In the field of radar, relative bandwidth is usually used to distinguish wideband and narrowband signals. Relative bandwidth refers to the ratio of the signal bandwidth to its center frequency.

The stepped frequency signal is an important radar signal with a high range resolution. It uses sequential transmit of multiple equal-width pulses or sub-pulses with a linear stepping center frequency, and with the use of the synthetic pulse compression processing, a high-resolution range profile can be achieved. The stepped frequency signal features an instantaneous narrow band but a broad synthetic bandwidth. For stepped frequency signals, amplitude and phase correction can be made on each frequency separately to avoid signal distortion. Doppler processing can be performed on multi-frame stepped frequency signals to obtain a high Doppler resolution, and then synthetic wideband processing can be performed to achieve two-dimensional high-resolution range-Doppler images. This two-dimensional high resolution of the stepped frequency signal holds great advantages in vibration measurement, target recognition and anti-jamming.

The development of wideband phased array radar is required by space target observation. Space targets mainly include satellites, space stations, spacecraft, space debris and ballistic missiles. Since there are long distances between the observers and the space targets, the ground-based radar first needs a large detection range, generally as far as 1000–5000 km. To enable imaging of satellites and space debris and to distinguish warheads from decoys, space target detection radars also usually require a large signal bandwidth for high range resolution. Additionally, to perform the detection in a large airspace, the space target detection radar should also have fast beam scanning and beam forming capabilities as well as multi-target detection and tracking capabilities.

Large range coverage, high resolution, and multiple targets are the basic characteristics of wideband phased array radar. Compared with mechanically scanning radar, phased array radar has a highly improved detection capability for multi-targets, target groups, high-speed targets and long-range targets. Compared with narrowband radars, wideband radars can obtain a high range resolution, which effectively enhances radar performance by providing more target information to classify and identify targets. The combination of phased array technology and wideband radar technology provides superior functionality that meets many new requirements placed on modern radars systems.