RU2199824C2 - Method for radio suppression of electronic communication facilities using adaptive antenna arrays - Google Patents

Abstract

FIELD: electronic warfare. SUBSTANCE: proposed method is used for radio suppression of confronting-side electronic communication facilities where adaptive antenna arrays are used to enhance their noise immunity and may be found useful for radio suppression systems and complexes. Method involves jamming at frequency equal to reception frequency of electronic communication facility being suppressed and radiation of this radio noise to set up amplitude-phase distribution of noise currents at outputs of adaptive array antennas identical (or close to identical) to amplitude-phase current distribution of signal being suppressed from definite direction typical of adaptive antenna array. EFFECT: enhanced suppressive action of electromagnetic radiation energy on confronting-side radio communication facilities. 2 dwg, 2 tbl

Description

 The invention relates to the field of electronic warfare (EW), namely radio suppression (RP) of radio electronic means (RES) of communication, in which adaptive antenna arrays (AAR) are used to increase noise immunity, and can be used in systems and complexes of electronic suppression (REP), to achieve a higher suppressive effect of the energies of electromagnetic radiation on the communication RES of the opposing side.

 At present, for the effective operation of radio communication systems, especially in the conditions of application of optimized interference and intensive RP, various, fundamentally new scientific and technical solutions are being sought to increase noise protection, one of which is the use of adaptive antenna arrays.

 Adaptive antenna array - an antenna array whose parameters (first of all, directivity) are automatically changed in such a way as to provide the best or nearing the best conditions for receiving a useful signal against the background of changing external influences (interference).

 The use of AAR to increase the interference immunity of communication RES is based on taking into account differences in the directions of arrival of interference and a useful signal. In reality, such differences always exist, except in situations where the directions of arrival of the interference and the useful signal coincide. These differences cause a difference in the amplitude-phase distribution of the noise currents and the useful signal at the outputs of the antenna elements (AE) of the AAR spaced apart in space. In turn, the use of differences in the amplitude-phase distribution of the currents of the useful signal and interference allows the AAR to be formed in such a way that a maximum is formed in the direction of arrival of the useful signal, and minimums ("zeros") of its DN are correspondingly in the directions of arrival of interference .

 At the same time, the informational confrontation also requires the development of fundamentally new scientific and technical solutions for radio suppression methods, the use of which will lead to difficulties and, ultimately, to disruption of the functioning of communication RES, including communication RES using AAA.

 Currently known methods of RP.

 The method of RP communication RES, in general, and communication RES using AAR, in particular, the essence of which is described in the book by A. Paly. Electronic warfare. M .: Military Publishing House, 1989, p. 28. This method involves setting two or more flickering synchronous radioelectronic interference with frequencies coinciding with the frequencies of the reception of the “useful signal” (hereinafter, under the term “useful signal” we will consider only the useful radio signal for of the suppressed communication RES, and radio-electronic interference with frequencies equal to the frequencies of the reception of the useful signal suppressed by the communication RES, we will call the interference) of the suppressed communication RES.

 However, this method has disadvantages: the need for 2 or more REP stations spaced on the ground, and the need to synchronize their work in time.

 There is also known a method of radio suppression of communication RES using AAR, the essence of which is described in the book Monzingo R.A., Miller T.U. Adaptive antenna arrays. Introduction to the theory. M .: Radio and communications, 1986, p. 36. This method involves setting L spatially separated interference, where L> (N-1), here N is the number of antenna elements (AE) in the AAR (N-element AAR can form N-1 independently controlled zeros of the beam).

 However, this method has a drawback, namely the need for a large number of REP stations. Indeed, if an AAR with N = 3 is used to increase the noise immunity, then this AAR is capable of generating two independent zeros of interference paths, and, accordingly, for radio suppression of a communication RES using such an AAR, at least three REP stations are required.

 The closest in its technical essence to the claimed method of RP is the method of radio suppression of communication RES, in general, and communication RES using AAR, in particular, described in the book Paliy A.P. Electronic warfare. M.: Military Publishing House, 1989, p. 51. This prototype method provides for the creation of interference with a power exceeding the power of the useful signal at the input of the AAR, i.e. the ratio of the interference power falling into the passband of the radio receiver of the communication RES to the useful signal power will exceed a certain minimum necessary value.

 However, this prototype method has a drawback: the need to create powerful interference, and, accordingly, a high-power REP station, since the AAR is able to create a “zero” beam with a depth of 20-25 dB or more in the direction of arrival of the interference, depending on the signal-noise environment and characteristics directly to the AAR itself.

 The problem to which the claimed invention is directed is to develop a RP method that improves the efficiency of electronic warfare systems, namely, provides a higher suppressing effect of electromagnetic field energy on the communication RES of the opposing side using AAR, in the case where the frequency, direction of arrival of the useful signal, defined relative to the normal to the AE location line, the location and characteristics of the antenna array (AR) itself are known.

 The problem is solved using the proposed method, which consists in the creation of electronic interference, the frequency of which is equal to the frequency of reception of the suppressed RES radio communications, and its radiation from a specific direction typical for AAR. Moreover, in contrast to the known prototype method, the interference power at the input of the adaptive antenna array may not exceed the power of the useful signal.

 A distinctive feature of the proposed RP method is the choice of the direction of the interference radiation, which allows you to create the amplitude-phase distribution of the interference currents at the outputs of the antenna elements of the AAR, identical (or close to identical) the amplitude-phase distribution of the currents of the suppressed signal (useful signal), and, accordingly, the interference will not only accepted, but also strengthened by AAR along with a useful signal.

 When analyzing the directional patterns of the AAR, it can be seen that when the maximum of the beam is formed in the direction of arrival of the useful signal by the adaptive antenna array, at least one more will also be formed, let's call it "spurious", the maximum of the beam, oriented in the other direction. Moreover, the direction of this "spurious" maximum is strictly related to the direction of the maximum of the beam oriented in the direction of arrival of the useful signal.

As an illustration, figure 1 presents the normalized radiation pattern of AAR obtained by simulation on a computer. The following assumptions about the characteristics of the AR and the signal-noise environment were used in the simulation: antenna array (AR) linear equidistant N = 3, interelement distance d = λ / 2 (λ is the wavelength of the signal), AEs are isotropic and noninteracting; the carrier frequencies of the signal and interference are identical f _c = f _n = 300 MHz (λ = 1 m); the angle of arrival of interference (relative to the normal to the line of location of the AE) θ _p = 60 ^° ; angle of arrival of the useful signal θ _c = 30 ^° ; input signal-to-noise ratio 10lg (Pc / σ $\genfrac{}{}{0ex}{}{\text{2}}{\text{w}}$ ) = 10 dB; input noise-to-noise ratio 10lg (Pn / σ $\genfrac{}{}{0ex}{}{\text{2}}{\text{w}}$ ) = 20 dB; where σ $\genfrac{}{}{0ex}{}{\text{2}}{\text{w}}$ - dispersion of thermal noise.

As can be seen from the presented graph, in addition to the maximum of the ND oriented in the direction of arrival of the signal (θ _c = 30 ^° ), AAP forms another maximum oriented in the direction of θ _n = 150 ^° . When interfering in this direction, it will be received and amplified by AAR in the same way as a useful signal, and accordingly, the communication RES will be practically suppressed. This effect is explained by the fact that the signals arriving from the indicated directions (θ _c = 30 ^° ; θ _p = 150 ^° ) will at the outputs of the AE of the antenna array excite currents that are identical not only in frequency but also in phase, and therefore will there is no possibility of their spatial separation. In the future, the directions of arrival of signals, upon reception of which currents at the AE AAR outputs will be excited, which are identical not only in frequency but also in phase, will be called "coherent".

 In the case where the frequency, direction of arrival of the useful signal, determined relative to the normal to the line of location of the AE, the location and characteristics of the antenna array itself (AR) are known, coherent directions can be uniquely determined.

 Since it is quite problematic to obtain an analytical expression for determining "coherent" directions, depending on the frequency, directions of arrival of the useful signal, location and characteristics of the AR itself, these directions are proposed to be obtained by computer simulation.

The inventive method of RP is as follows:
1. Using a priori information about the frequency, direction of arrival of the useful signal, location and characteristic of the AR, the "coherent" directions of its beam pattern are determined.

 2. A noise is formed with a frequency coinciding with the frequency of the useful signal.

 3. Using a mobile base (automobile, helicopter, aircraft), the REP station moves to a specific place, from where the interference is emitted.

 In order to reduce the time needed to determine “coherent” directions, they can be determined in advance for various, most typical ARs, frequencies and directions of arrival of a useful signal and are tabulated.

 So, for example, an analysis of the dependence of the linear, equidistant antenna array with an optimal inter-element distance d = λ / 2 (λ is the wavelength of the useful signal) on the direction of arrival of the useful signal, made it possible to “generalize” the directions and summarize them in Table 1.

 With a change in the distance between the elements, the introduction of non-equidistance or non-linearity of the AR arrangement, in addition to the indicated directions, additional “coherent” directions appear along which interference can also be set. So, for example, when the interelement distance changes to the value d = λ, in addition to the directions presented in Table 1, at least two more “spurious” maximums of the ND (coherent directions) appear.

 The analysis of the dependence of the AAR bottom plate with an interelement distance d = λ on the direction of arrival of the useful signal, carried out by simulation, allowed the “coherent” directions to be generalized and summarized in Table 2.

 A detailed comparison of the capabilities of the proposed method and the prototype method of RP signals was carried out using the simulation method, which further confirms the possibility of its technical implementation.

As an illustration, Fig. 2 shows the dependence of the signal / (interference + noise) (SINR) relationship at the AAR output on the input noise / noise ratio obtained by simulation. In the simulation, we used the above assumptions about the characteristics of the AR and the signal-noise environment, with the exception of the direction of jamming, namely, the noise was set along the “parasitic” maximum of the beam (coherent direction) θ _n = 150 ^° (curve 1). For comparison, in the same drawing, curve 2 shows the dependence of the SINR at the output of the AAR on the input interference / noise ratio when interfering with another direction of interfering other than those proposed in the table, namely θ _p = 60 ^° .

 As can be seen from the above graphs, in the case of jamming in the so-called "coherent" direction, it is possible to suppress the communication RES using AAR, one interference with a relatively low power level.

 This advantage of the proposed method of suppressing radio lines using AAR, will increase the efficiency of electronic warfare systems.

Claims (1)

 The method of radio suppression of electronic means using adaptive antenna arrays, which consists in creating electronic interference with a frequency equal to the frequency of reception of the suppressed electronic means of communication, characterized in that the electronic interference is emitted using a priori information about the frequency, direction of arrival of the suppressed signal, location and characteristics of the adaptive antenna array in the direction of the "spurious" maximum radiation pattern of the adaptive antenna array, formed when forming the maximum of the radiation pattern of the adaptive antenna array in the direction of arrival of the suppressed signal that is rigidly connected with it and oriented in the other direction, the amplitude-phase distribution of the radioelectronic noise currents at the outputs of the antenna elements of the adaptive antenna array is identical to the amplitude-phase distribution of the currents of the suppressed signal.

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