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The increasingly complex electromagnetic environment of modern warfare and the proliferation of intelligent jamming threaten to reduce the survival rate of radio fuzes on the battlefield. Radio frequency (RF) stealth technology can fundamentally improve the anti-interception and reconnaissance capabilities of radio fuzes, thereby lessening the probability of them being intercepted, recognized, and jammed by the enemy. In this paper, an RF stealth waveform based on chaotic pulse-position modulation is proposed for ultra-wideband (UWB) radio fuzes. Adding a perturbation signal based on the Tent map ensures that the chaotic sequences have sufficiently long periods despite hardware byte limitations. Measuring the approximate entropy and sequence period shows that the Tent map with the addition of perturbation signals can maintain good randomness under byte constraints, closely approximating the Tent map with ideal precision. Simulations verify that the proposed chaotic mapping used to modulate the pulse position of an ultra-wideband radio fuze signal results in superior detection, anti-interception, and anti-jamming performance. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasingly complex electromagnetic environment of modern warfare and the proliferation of intelligent jamming threaten to reduce the survival rate of radio fuzes on the battlefield. Radio frequency (RF) stealth technology can fundamentally improve the anti-interception and reconnaissance capabilities of radio fuzes, thereby lessening the probability of them being intercepted, recognized, and jammed by the enemy. In this paper, an RF stealth waveform based on chaotic pulse-position modulation is proposed for ultra-wideband (UWB) radio fuzes. Adding a perturbation signal based on the Tent map ensures that the chaotic sequences have sufficiently long periods despite hardware byte limitations. Measuring the approximate entropy and sequence period shows that the Tent map with the addition of perturbation signals can maintain good randomness under byte constraints, closely approximating the Tent map with ideal precision. Simulations verify that the proposed chaotic mapping used to modulate the pulse position of an ultra-wideband radio fuze signal results in superior detection, anti-interception, and anti-jamming performance.

Different from the phased-array with the same carrier frequency for all elements providing only angle-dependent beampattern, frequency diverse array (FDA) using a small frequency offset across its array elements offers new application capabilities due to its both angle and range dependent beampattern, which allows auto beam-scanning capability even without the employment of phase shifters, which are required in phased-array. This paper studied FDA auto-scanning beam characteristics and several potential radar applications. The FDA auto-scanning beam characteristics including range and angle coupling, beam auto-scanning rate and integral array again are analyzed. To fully utilize FDA specific auto-scanning beam characteristics, several potential applications such as radio frequency (RF) stealth or RF localization deception, range-ambiguous clutter suppression and mainlobe interference suppression are discussed. Moreover, several discussions about space-time adaptive processing and possible future investigations are provided. This paper is formulated from a top-level system description, which aims to introduce this promising FDA technique to radar community so that more investigations can be facilitated.

Frequency diverse array (FDA) produces an angle range dependent and time-varying transmit beampattern due to the small frequency increment across its array elements, which provides potential applications for secure communications and radio frequency stealth. In this article, we study the low probability of intercept (LPI) properties of FDA transmitted signals under typical passive reconnaissance techniques. First, the passive reconnaissance property of direction-of-arrival estimation for FDA transmitted signals under phase interferometry measurement is evaluated, together with the corresponding Cramér–Rao bound analysis. Second, the passive reconnaissance property of time difference of arrival and frequency difference of arrival estimation for FDA transmitted signals are also evaluated for moving platforms. Both theoretical analysis and numerical results demonstrate that FDA transmitted signal indeed achieves significantly better LPI performance than phased-array transmitted signals, which is particularly useful for military applications. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the continuous development of modern electronic confrontation technology and military equipment, the detection ability of passive detection system to aircraft and its active electronic equipment has been significantly improved. The survivability and penetration ability of aircraft in modern combat environment are seriously threatened. Aircraft radio frequency (RF) stealth technology is an important technical way to improve aircraft battlefield survivability by controlling the RF radiation of airborne radar, data link, altimeter, electronic confrontation and other active electronic equipment, and plays an important role in today7 s battlefield. In this paper, the research of aircraft RF stealth technology is overviewed. Firstly, the basic concept and research status of RF stealth technology are described, and the basic principle and realization way of RF stealth technology are introduced. Then, the research achievements in the field of RF stealth technology are reviewed from the aspects of RF stealth performance evaluation system, minimum radiation power control, low sidelobe digital beamforming of design RF stealth signal waveform, multi-sensor cooperation and management, etc. Finally, based on the summary and analysis of the existing research achievements, aiming at the problems existing in the development of RF stealth technology, the future development trend of aircraft RF stealth technology is prospected. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to counter passive direction-of-arrival (DOA) reconnaissance for unintended eavesdroppers, this letter proposes the use of frequency diverse array (FDA) to counteract passive DOA reconnaissance using a virtual baseline interferometer. FDA applies a small frequency offset across its array elements to generate an angle-range-dependent and time-variant transmit beampattern, which provides a potential capability to achieve radio frequency (RF) stealth and localization deception for eavesdropping receivers. We analyzed the DOA localization deception of FDA transmitting signal, together with simulation examples. The results show that, while compared to conventional phased-array transmitting signal, RF localization deception of DOA estimation is indeed achieved for the FDA transmitted signals, which provides promising potentials for future secure radar and communication applications. [ABSTRACT FROM AUTHOR]

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The feasibility of using plasmatized exhaust to reduce engine rear bistatic radar cross section (RCS) is studied. The possible range of plasma density inside a jet engine when alkaline additives are used in fuel is analyzed via the Saha equation, and the results show that there should be high density plasma. Next, the S-band rear bistatic RCS of a jet engine with or without the vector thrust nozzle is simulated using a finite-difference time-domain code. Then, the RCS when exhaust is plasmatized is simulated to make comparison. The results show that even with low density plasma, the effective shape of the vector thrust nozzle is changed, and the RCS is reduced. As the plasma density becomes higher, the reflection becomes stronger and the radar wave penetration into the plasmatized exhaust becomes less. The change in RCS is strongly related to the direction and shape of the jet exhaust, besides the plasma density. [ABSTRACT FROM PUBLISHER]

Inspired by a cognitive radar in exploiting its environment to update current operation parameters and frequency diverse array (FDA) in offering a range-dependent beampattern due to the employment of frequency increments across the elements, this paper proposes a moving-target tracking approach to achieve cognitive radio frequency stealth using an FDA antenna for surveillance applications. Since surveillance systems are highly visible to intercept receivers, a traditional high-gain phased-array antenna beam is replaced by a series of low-gain FDA beams with spoiled frequency increments to reduce the system visibility, without degrading the surveillance system performance. Moreover, a cognitive closed-loop update scheme is presented to update the operation parameters in real time for improved moving-target tracking performance. All of the proposed methods are verified by simulation results. [ABSTRACT FROM AUTHOR]

For the power control problem of defensive electronic countermeasures (DECM) in the condition of radio frequency (RF) stealth, the characteristic of blanketing jamming and deception jamming of DECM is analyzed. The relationship between effective jamming and RF stealth of DECM is discussed and models of RF stealth characteristic of DECM are established. The power control methods of blanket ratio effective boundary and signal jamming ratio effective boundary are presented. According to the mutual closed loop feature of electronic countermeasures, the RF stealth factor of DECM is established, which is the radio of intercept ranges before and after using power control methods. Simulation proves that power control methods of DECM are effective. [ABSTRACT FROM AUTHOR]