System Design and Signal Processing for Frequency Diverse Array Radar

Frequency diverse array(FDA)radar has been studied for more than 15 years and has attracted a lot of attention due to its potential advantages over the well-known phased array radar.The representative feature of FDA is range-angle-time-dependent transmit beampattern and its underlying properties are continuously revealed in the research.The formulation and exploitation of the transmit diversity with a frequency increment is the fundamental principle,which brings extra degrees-of-freedom(DOFs)in the transmit dimension.As the FDA radar carries additional information in range,it provides more flexibility in signal processing and also brings in new technical issues.This article overviews the state-of-the-art in FDA radar area and its applications,mainly based on the progress in our group.There are two main catalogs in FDA radar area,namely coherent FDA and FDA-MIMO(multiple-input multiple-output)radars.Potential applications including target parameter estimation,ambiguous clutter suppression,and deceptive jammer suppression are discussed.

An Active Anti-Jamming Approach for Frequency Diverse Array Radar with Adaptive Weights

Due to the rapid development of electronic countermeasures(ECMs),the corresponding means of electronic counter countermeasures(ECCMs)are urgently needed.In this paper,an act-ive anti-jamming method based on frequency diverse array radar is proposed.By deriving the closed form of the phase center in a uniform line array FDA,we establish a model of the FDA signal based on adaptive weights and derive the effect of active anti-jamming in this regime.The pro-posed active anti-jamming method makes it difficult for jammers to detect or locate our radar.Fur-thermore,the effectiveness of the two frequency increment schemes in terms of anti-jamming is ana-lyzed by comparing the deviation of phase center.Finally,the simulation results verify the effective-ness and superiority of the proposed method.

Dot-shaped beamforming analysis based on OSB log-FDA

The range and angle information of the frequency diverse array(FDA) cannot be exclusively determined at the output of the array because of the range-angle coupled transmit beampattern. The best decoupling approach is to form a dot-shaped beampattern rather than the S-shaped beampattern of the basic FDA.Considering the degradation of the output signal-to-interferenceplus-noise ratio(SINR) caused by the coupled beampattern, we propose a dot-shaped beamforming method based on the analyzed overlapping subarray-based using a logarithmic offset and a subarray-based planar FDA using a logarithmically increasing frequency offset, with elements transmitting at multiple frequencies. Several simulation results demonstrate the effectiveness of the proposed method in transmit energy focusing, sidelobe suppression and array resolution.

时空可控点聚焦FDA的动目标跟踪研究

提出了一种基于多载频时间调制频偏的时空可控点聚焦频率分集阵列天线。首先,实现对动目标的跟踪,在频偏中引入一个时间补偿因子,以避免可能出现的频率奇异性,使得连续频率调制的持续时间远大于周期调制的持续时间;然后,根据目标实时位置计算频偏,实现目标在运动全程中保持波束聚焦于目标点处;最后,通过运动目标跟踪的仿真算例验证了方法的有效性。

Deceptive jamming discrimination based on range-angle localization of a frequency diverse array

We propose a method to suppress deceptive jamming by frequency diverse array （FDA） in radar electronic coun- termeasure environments. FDA offers a new range-angle-dependent beam pattern through a small frequency increment across elements. Due to the coupling between the angle and range, a mismatch between the test angle and physical angle occurs when the slant range on which the beam focuses is not equal to the slant range of the real target. In addition, the range of the target can be extracted by sum-difference beam except for time-delay testing, because the beam provides a range resolution in the FDA that cannot be deceived by traditional deceptive jamming. A strategy of using FDA to transmit two pulses with zero and nonzero frequency increments, respectively, is proposed to ensure that the angle of a target can be obtained by FDA. Moreover, the lo- calization performance is examined by analyzing the Cramer-Rao lower bound and detection probability. Effectiveness of the proposed method is confirmed by simulation results.

频率分集阵雷达技术探讨

频率分集阵(Frequency Diverse Array,FDA)雷达不同天线单元的发射载频存在微小的差异,从而带来了发射方向图距离角度时间依赖的特性,这一特性提供了FDA雷达新的信息和信号处理灵活度,也带了新的技术问题。该文综述了FDA天线技术及雷达应用的相关研究进展,并重点从雷达系统理论与工程应用的角度,着重分析了相干FDA雷达和正交FDA雷达两种体制的技术特点,指出FDA雷达在抗干扰、抗模糊中的应用优势,梳理了FDA雷达技术的难点和研究方向。

频率分集阵列及其研究进展

与只提供角度依赖天线方向图的相控阵不同,频率分集阵列(FDA)在每个阵元上引入了载频差,以提供距离-角度相关的天线方向图,这使得FDA具有抑制距离模糊杂波、抗距离依赖性干扰等相控阵没有的优点。简要介绍了FDA的基本原理、波束形成和接收处理机制,梳理了FDA的研究进展,主要包括目标位置估计、FDA与MIMO雷达结合抗干扰、在SAR成像中的应用以及机载雷达距离模糊杂波抑制等4个方面,最后分析了FDA雷达在实际应用中所面临的两个关键问题以及应用前景。

频率分集阵列接收机结构设计及方向图分析

针对频率分集阵列(FDA)存在的发射方向图与接收方向图不聚焦、波束时变等问题,给出了三种FDA阵列接收机设计方案.在接收机设计中,基于频域滤波器和正交波形设计,实现了接收端各阵元信号的分离,解决了发射方向图与接收方向图在期望位置不聚焦的问题;通过二次下变频,消除了接收方向图的时变项,解决了方向图的时变性问题.理论推导及仿真结果表明该接收机结构的双程方向图处理增益、主副瓣比及主瓣驻留时间等主要性能指标均优于相控阵结构.