Phase-switched Screen Research Articles

Phased Array Radar Resource Consumption Method Based on Phase-Switched Screen

The consumption of phased array radar (PAR) resources affects the accuracy of its multi-target searching and tracking abilities. The jamming methods aimed at PAR involve deceptive jamming and comprehensive jamming strategies, but have the disadvantages of high cost and complexity. Given this context, this paper proposes a PAR resource consumption method based on phase-switched screen (PSS), and derives a relationship between the targets and the evaluation indicators. By implementing periodic modulation of PSS, a controlled number of deceptive multiple false targets can be generated, thereby enticing the radar system to engage in activities such as searching and tracking targets. When the quantity of false targets is increased, the number of beam requests becomes five times higher than compared to the scenario without false targets. This has also led the margin of time resources to exceed 50%, successfully achieving the objective of consuming radar resources. Furthermore, this method offers straightforward manipulation, flexibility, and the potential to significantly consume radar resources. The efficacy of the proposed method is confirmed with the simulation outcomes.

Track False-Target Deception Method Based on Phase-Switched Screen

Track processing is the foundation of radar multi-target tracking, and the processing performance for jamming has particular research significance when it comes to protecting high-value targets. At present, passive jamming using a modulated metasurface exhibits a fast response and a flexible operation mode. However, most research in this area has been carried out at the radar signal processing level and less at the data processing level. In this paper, a range of false target track deception method based on a phase-switched screen (PSS) is proposed, and the relationship between the matched filtering output, radar detection, and track processing is derived. This method uses PSS to generate multiple false targets with controlled spatial distribution and magnitude, which can form high-fidelity false tracking tracks. The number of false tracking tracks can be flexibly altered by controlling the modulation parameters. The simulation results validate the effectiveness of the proposed method.

Phase Switched Screen for Radar Cloaking Based on Reconfigurable Artificial Magnetic Conductor

Phase switched screen (PSS) has been proposed for more than two decades for its applications on radar cloaking. However, the PSSs in most publications need a thickness of one-quarter wavelength to realize perfect cloaking at the operating frequency of the incident radar-detecting wave, which seems too thick for engineering. In this article, a new design of the dual-band artificial magnetic conductor (AMC) is proposed in which the electromagnetic band gaps are shifted among two bands by adjusting the biasing current on the four p-i-n diodes. By controlling the states of the diodes between <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> , the in-phase reflection frequency of the AMC can switch from 2.5 to 5.3 GHz. Based on the AMC structure above, a potential dual-band PSS is realized through different switching schemes and, therefore, achieves good stealth effects during the two bands above.

An Inverse Synthetic Aperture Radar Image Modulation Method Based on Coding Phase-Switched Screen

Multiple false target images deception is an effective strategy to protect vital military targets from detection and recognition by inverse synthetic aperture radar (ISAR). Previous research about it focuses mainly on the interrupted-sampling and sub-Nyquist sampling repeater jamming based on digital radio frequency memory (DRFM). The digital image synthesis (DIS) technique or scatter-wave modulation is used to simulate electromagnetic scattering of the real target. However, it is difficult to realize due to the high reconnaissance accuracy requirement and a heavy computational burden. Moreover, the protected target remains in the same location and the false targets' amplitude envelope based on periodic modulation is relatively fixed, which is not conducive to deception. In this paper, an ISAR image modulation method based on coding phase-switched screen (PSS) is proposed against ISAR. The method uses the target bait made of PSS or attaches the PSS to the protected target surface to impose phase modulation onto the reflected signal. As a result, multiple false target images with verisimilar properties are formed around the protected target position when the reflected signal is received and processed by the victim ISAR. Besides, the protected target is concealed and the flexible amplitude control of false targets is achieved. The simulation results are performed to verify the effectiveness of the proposed method.

Synthetic Aperture Radar Image Modulation Using Phase-Switched Screen

Synthetic aperture radar (SAR) image modulation is an effective method to protect a target of interest, and thus receives intensive attention. Currently, it still remains challenging to design an image modulation method capable of both flexibility and diversity in a passive way. In this letter, a two-dimensional (2-D) image modulation method based on phase-switched screen (PSS) is proposed against the SAR. The method imposes phase modulation onto the radar reflected signal by the PSS so that 2-D multifalse targets with verisimilar characteristics are formed around the protected target position when received and processed by the victim radar receiver. The theoretical analysis indicates that the amplitude and position of the generated multifalse targets are precisely controlled by the PSS modulating parameters. Moreover, the protected target is concealed and cannot be detected by radar. Simulations and experimental results are conducted to illustrate the validity of the proposed method.

Synthetic Aperture Radar Target Feature Transformation Method Based on Random Code Phase-Switched Screen

As a novel passive device, phase-switched screen (PSS) imposes phase modulation onto the radar signal and has been extensively applied in radar target stealth. Recently, the blanket jamming method based on PSS is proposed against synthetic aperture radar (SAR). However, the method still remains challenging to obtain the desired jamming effect because it suffers from insufficient energy when the reflectivity of the reflector is not enough or the protected area is too large. In this paper, a target feature transformation method based on PSS is proposed to counter SAR. The method attaches the PSS material to the protected target surface and utilizes one-dimensional (1-D) or two-dimensional (2-D) random code PSS modulation to dynamically control the reflected signal. As a result, the generated target image is defocused and turned into some strip-shaped or square-shaped areas when modulated signal is received and processed by the victim radar system. The target feature is transformed greatly and cannot be detected by radar. Moreover, the shape of the generated area can be flexibly controlled by the code width and inter-pulse modulating frequency. Simulations and experimental results are utilized to verify the effectiveness of the proposed method.

Improved synthetic aperture radar micro‐Doppler jamming method based on phase‐switched screen

Target micro-motions such as rotation and vibration introduce phase modulation, termed as micro-Doppler (m-D) effect, onto synthetic aperture radar (SAR) signals. This causes ghost targets in the reconstructed SAR images. Inspired by this unique characteristic, a passive-jamming method based on m-D was developed for SAR. The m-D jamming method utilised a rotating reflector to intentionally generate ghost targets as jamming strips on the SAR image so as to protect certain areas. The m-D jamming method based on a single rotating reflector can only generate a long jamming strip along the azimuth direction but located in a finite number of range cells, which restricts the region of protected scene. In this study, an improved m-D jamming method based on phase-switched screen (PSS) is proposed, which combines the advantage induced by the PSS modulation and the usefulness of the m-D jamming. By controlling the modulating frequency and waveform of the PSS, the jamming strip is enlarged along the range direction. Theoretical analyses and simulation results verify the validity of the proposed method.

Matched‐filter properties of linear‐frequency‐modulation radar signal reflected from a phase‐switched screen

The phase-switched screen (PSS) imposes phase modulation onto the radar-reflected signal so that its energy is redistributed into sidebands that lie outside the receiver pass-band. However, when illuminated by a wideband linear frequency modulation (LFM) radar, the modulated reflected signal may still occupy the radar pass-band if the LFM signal bandwidth is greater than the modulating frequency. Previous research about the reflectivity performance of a PSS against LFM radar illumination focuses mainly on the frequency spectrum characteristics. In this study, an investigation has been carried out to determine the matched-filter properties of an LFM radar signal modulated by a PSS. Theoretical analyses and simulation results have proven that even though the radar receiver bandwidth has been corrupted to aliasing by component of the reflected signal, the PSS is shown to be equally effective in shielding a target and additionally provide a multiple-decoy capability.

High-Resolution Range Profile Deception Method Based on Phase-Switched Screen

High-resolution range profile (HRRP) has been useful in the support of target characterization and thus receives intensive attention. It is still a challenging task to design a deception method capable of both generating false-target HRRPs and concealing the real-target HRRP. In this letter, an HRRP deception method based on phase-switched screen (PSS) is proposed. This method utilizes PSS to impose phase modulation onto the radar reflected signal so that multiple false targets with verisimilar HRRP characteristics appear symmetrically around the real-target position. Meanwhile, the real-target HRRP is concealed and may not be detected by radar. Experimental results are used to verify the correctness of the analyses.

Dielectric phase-switched screen

Conventional radar absorbent materials rely on the absorption and conversion into heat of the electromagnetic energy incident upon them. In an alternative approach, the phase-switched screen (PSS) uses a switchable resistive layer to apply binary phase modulation to the reflected signal so that its energy is redistributed into sidebands that lie outside the receiver passband. Here, the characteristics of an alternative type of PSS, whose efficacy depends on periodic changes in the permittivity or permeability of a dielectric layer, are considered. This leads to the concept of the pseudo-multi-layer dielectric PSS, which mimics the performance of a multi-layer absorber but comprises of only a single layer.

SSB-Type Frequency Scattering From a Single-Layer PSS With Interlaced Element Modulation

Experimental results are been presented to show that when a phase-switched screen (PSS) is configured so that alternate rows of the its active surface are modulated with independent square-wave signals, single side-band (SSB)-type frequency modulation can be imposed onto signals scattered from the PSS surface. By adjusting the phase-offset between the two modulating signals, selective suppression of individual upper and lower sidebands can be achieved

RCS reduction of spiral patch antenna using a PSS boundary

The use of a phase-switched screen (PSS) boundary to control the radar cross-section (RCS) of a spiral patch antenna is investigated. A theoretical analysis based on a transmission line analogue is used to examine the concept and to provide basic design criteria. The design of an experimental system that includes a novel dual polarised active PSS boundary is described. Measured results are presented, which show that the demonstrator system provides active RCS control between 11 GHz and 13 GHz.

Experimental performance of a phase-switched screen against modulated microwave signals

Experimental results describing the performance of an active phase-switched screen (PSS) radar absorber operating against modulated microwave signals are presented. A planar PSS is illuminated by pulse modulated and FM modulated radar signals with a carrier frequency of 11 GHz. The measured frequency spectrum of the reflected signals from the PSS in both its active and passive states are presented and compared to theoretical predictions.

Reflectivity null tuning in multi-layer phase-switched active radar absorbers

An ‘array’ polynomial approach is used to predict the positions of the reflectivity nulls for an ideal phase-switched screen (PSS) having many active layers. Several layer-switching schemes are examined and it is found that the resulting null position diagrams exhibit bifurcation behaviour similar to that found in many dynamical systems. The chaotic state is never achieved, however, since the ideal PSS is a linear system.

A smart radar absorber based on the phase-switched screen

Although conventional (i.e., passive) radar absorbers are widely used for modifying the radar cross-section (RCS) of current military platforms, such absorbers may not have adequate performance to satisfy future requirements. Active absorbers, however, offer the potential to overcome the so-called Rozanov performance limit and to enable additional smart functionality such as monitoring damage, adaptive control of RCS or target appearance, identification-friend-or-foe, and absorb-while-scan. This paper outlines the concept and basic properties of a novel type of active radar absorber, the so-called phase-switched screen (PSS). The basic PSS topology is then modified so as to enable it to operate as a smart radar absorber when used together with an external sensor and feedback control loop. System implementation issues and the optimum choice of design parameters for a range of operational scenarios are discussed, and theoretical predictions are supported by measured performance data.

The phase-switched screen

Conventional (passive) radar-absorbent materials operate either by phase cancellation or by absorbing incident electromagnetic energy and converting it into heat. This paper examines a new type of active "absorber," called the phase-switched screen (PSS). The PSS operates quite differently from passive absorbers in that it exhibits an apparently low value of reflectivity by redistributing the electromagnetic energy incident upon it over a bandwidth that is wide enough to ensure that little reflected energy falls within the pass-band of the receiver. The discussion considers the basic temporal and spectral properties of several PSS topologies, and includes measured data on both planar and cylindrical PSS structures.

Single layer phase-switched screen using double-diode switching elements

A new form of phase-switched screen is demonstrated in which each dipole element in the active layer is loaded by an antiparallel pair of pin diodes. The advantages of this arrangement are that the diode control voltage is of sine wave, rather than square wave form, the effective switching frequency is doubled, with a consequent improvement in scattered spectral characteristics and each pin diode is inherently protected against large peak inverse voltage burnout caused by abnormally large incident electromagnetic fields.

Experimental cylindrical phase-switched screen

An experimental cylindrical phase-switched screen (PSS) is described. Design details for both TE and TM cylindrical PSS are given and the measured performance of the resulting structures is presented. Results show that both TE and TM cylindrical PSS provide deep reflectivity nulls over a significant bandwidth.

Experimental dual polarised phase-switched screen

A new experimental dual polarised phased-switched screen (PSS) is described. Measured data is used to synthesise the operation of the PSS when modulated with a periodic square wave. Results are presented to confirm the operation of the screen at normally incident polarisation angles of 0°, 45° and 90°.

Influence of switching-waveform characteristics on the performance of a single-layer-phase switched screen

Conventional microwave-absorbing materials rely on the absorption and conversion into heat, of the electromagnetic energy incident upon them. In an alternative approach, the phase-switched screen (PSS) applies phase modulation to the reflected signal so that the energy is redistributed into sidebands with, ideally, none remaining at the original incident carrier frequency f/sub c/. Hence, by adjusting the frequency and shape of the waveform that controls the PSS reflection coefficient, these sidebands may be positioned outside the pass-band of a receiver tuned to f/sub c/. An investigation has been carried out to determine how the choice of control waveform and switching frequency influence the PSS performance.