Owing to the property of range-angle-dependent beampattern, frequency diverse array (FDA) has promising application potentials in radar field. Many studies have been reported to solve the time-variant problem of FDA. However, there is a misconception between the time index within pulse and the actual time, which misleads the theoretical analysis for FDA. In this paper, a novel understanding perspective is proposed to better distinguish the two kinds of time. The exact time-range and frequency-phase relationships are presented. In the sequel, the correction analysis about the operation theories of FDA considering the factor of time is presented along with the accurate understanding about the range-angle beampattern. Furthermore, based on the multiple input multiple output (MIMO) scheme with multiple matched filters at receiver, the prerequisite for exploring the range-dependent property of FDA is demonstrated. Simulations demonstrate the validity of theoretical results.

Due to the rapid progress of electronic countermeasures (ECMs), the corresponding means of electronic counter countermeasures (ECCMs) are urgently needed. Due to its range-dependent feature, frequency diverse array (FDA) radar technology possesses the application potential for mainlobe jamming suppression. However, the construction of the jamming model for FDA radar is a critical and challenging problem that has not been sufficiently studied. In this paper, based on the exact understandings of the time parameter and time-range relationship, the existing deceptive jamming models are analyzed and the correct modeling process is concluded. Furthermore, the complete signal processing flow related to the range parameter in the FDA radar is presented. Consequently, a novel deceptive jamming (NDJ) approach for FDA radar is proposed. NDJ can obtain the same beamforming gain as the target to avoid being suppressed at the beamforming level. Subsequently, effective deceptive jamming can be generated at different range bins to degrade the detection performance of the radar. Simulation examples demonstrate the effectiveness of our proposed method.

A miniaturized low-profile ultrawideband antipodal Vivaldi antenna (AVA) array loaded with edge techniques is presented to enhance mutual coupling. Originating from a conventional AVA, the edges of the adjacent elements are overlapped with shorted pins loaded to expand the low operating band, suppress the in-band resonance and achieve miniaturization. The edge truncation effect of the E-plane array is subsequently improved by adding auxiliary radiating arms and a shorted strip at the end. Eventually, an 8×8 finite array without any complicated feeding mechanism or transition is constructed to verify the design. The measured operating band of the AVA array is 0.9–12 GHz (13.3:1), and the measured active voltage standing wave ratio (VSWR) is less than 3 when scanning up to ±60° in both the E- and H-planes, implying its wideband and wide-angle scanning capability. Owing to its compact size, ultrawide band, wide-angle scanning and simple feeding structure, the proposed AVA array shows promise for application in large-scale arrays and communication systems.

Due to the rapid progress of electronic countermeasures, the corresponding means of electronic counter-countermeasures are urgently needed. To address the mainlobe jamming problem, frequency diverse array (FDA) radar has received extensive attention for its range-dependent feature. However, shortcomings arise such as the invading of new jamming styles that may degrade the detection performance along with the applications of FDA. In this letter, with the construction of accurate deceptive jamming models based on FDA multiple-input multiple output (FDA-MIMO), the suppression procedures are presented, which provide a new perspective for mainlobe jamming suppression considering the special jamming and drawbacks come along with FDA systems. At first, range-angle two-dimensional adaptive beamforming method is presented to eliminate the jamming model 1. Then range dimensional monopulse approach is proposed to alleviate the influence of jamming model 2. Simulation examples demonstrate the effectiveness of the proposed approach.

Frequency diverse array multiple-input multiple-output (FDA-MIMO) radar has received a lot of attention due to the advantages of waveform diversity. Suppression of mainlobe deceptive jamming can be effectively achieved with the degree of freedom (DOF) in the range domain. However, the existing research mainly focuses on non-coherent signals. The echo signal of VHF-FDA-MIMO radar for low elevation has its own unique characteristics. False targets cannot be suppressed with conventional beamforming methods. Thus, a signal model for VHF-FDA-MIMO radar subjected to deceptive jamming is established. The reconstruction of the covariance matrix and the estimation of the steering vector are implemented with the generalized MUSIC algorithm. In addition, a matching Capon reconstruction method is proposed to finish the robust suppression of false targets for the problem of self-cancellation in the absence of a priori information. Finally, the beampattern and performance curves of different methods are compared. The simulation results show that the methods can be effectively applied to the suppression of deceptive jamming in VHF-FDA-MIMO radar under the multipath effect.