阅读说明：本技术 基于飞行载体的四源非均匀线阵反向交叉眼干扰方法 (Four-source non-uniform linear array inverse cross eye interference method based on flight carrier ) 是由 王海军 徐忠富 刘海业 李金梁 贺正求 杨志飞 韩国强 刘一兵 任丙印 王继祥 于 2020-04-02 设计创作，主要内容包括：本发明属于雷达电子对抗技术领域,公开了一种基于飞行载体的四源非均匀线阵反向交叉眼干扰方法,是采用四个非均匀分布的阿基米德螺旋天线,组成线性的阵列天线,线性的阵列天线采用反向结构,在飞行载体的狭小空间上产生交叉眼干扰,其步骤一：采用阿基米德螺旋天线作为交叉眼干扰机天线；步骤二：单个干扰环路采用收发单天线的两源反向交叉眼干扰机结构；步骤三：确定两个干扰环路的干扰基线比；步骤四：对正视方向的单脉冲雷达进行交叉眼干扰。本发明可以有效干扰单脉冲测角雷达,为飞行体、无人机等小型飞行器突防提供有效防护,为交叉眼干扰技术的实用化应用提供支撑。对采用伴随式干扰的飞行器形成有效防护,有效提高了飞行器的突防能力。(The invention belongs to the technical field of radar electronic countermeasure, and discloses a four-source non-uniform linear array reverse cross eye interference method based on a flight carrier, which adopts four Archimedes spiral antennas which are non-uniformly distributed to form a linear array antenna, wherein the linear array antenna adopts a reverse structure, and cross eye interference is generated in a narrow space of the flight carrier, and the method comprises the following steps: an Archimedes spiral antenna is adopted as a cross-eye jammer antenna; step two: the single interference loop adopts a two-source reverse cross eye interference machine structure of a receiving and transmitting single antenna; step three: determining an interference baseline ratio of the two interference loops; step four: and performing cross-eye interference on the monopulse radar in the viewing direction. The invention can effectively interfere the monopulse angle measurement radar, provides effective protection for the sudden defense of small aircrafts such as a flying body, an unmanned plane and the like, and provides support for the practical application of the cross-eye interference technology. The aircraft adopting the adjoint interference is effectively protected, and the penetration capability of the aircraft is effectively improved.)

1. A four-source non-uniform linear array back-crossing eye interference method based on a flight carrier is characterized in that: a four-source non-uniform linear array inverse cross eye interference method for a monopulse angular radar based on a flight carrier adopts four non-uniformly distributed Archimedes spiral antennas to form a linear array antenna, the linear array antenna adopts a reverse structure, cross eye interference is generated in a narrow space of the flight carrier, and the method comprises the following steps:

the method comprises the following steps: an Archimedes spiral antenna is adopted as a cross-eye jammer antenna;

the method is characterized in that cross-eye interference is implemented in a narrow space of an aircraft platform, the main problem is the arrangement problem of cross-eye interference machine antennas, the isolation between the antennas is required to be ensured so as to reduce mutual interference, and a larger interference loop baseline ratio is required to obtain a large cross-eye interference gain; the cross-eye jammer antenna adopts an Archimedes spiral antenna, has wide frequency band, circular polarization, small size and convenient embedding in a frequency band range of 100 MHz-50 GHz, and has stable directional diagram, axial ratio and input impedance on the frequency band;

step two: the single interference loop adopts a two-source reverse cross eye interference machine structure of a receiving and transmitting single antenna;

the reverse cross-eye jammer is a cross-eye jammer adopting a reverse antenna structure, a reverse antenna array consists of a plurality of paired antennas, and signals are transmitted in two directions; the reverse antenna has the self-phase-adjusting characteristic, has two paths of interference signals with approximately equal amplitudes and opposite phases, and can interfere the monopulse radar;

the reverse antenna has a phase difference exceeding the tolerance of system parameters in a self-compensating interference loop, and the adoption of the reverse antenna array is a necessary condition of a cross-eye jammer;

the four-source non-uniform linear array inverse cross eye jammer is provided with two jamming loops, and a single jamming loop adopts a two-source inverse cross eye jammer structure of a transmitting and receiving single antenna; the two paths of interference signals are subjected to power attenuation and phase delay introduced by the same transceiving antenna, circulator, feeder line, component and feeder line, and the parameter matching between the two paths of interference signals is not influenced, so that the length of the feeder line is selected at will;

step three: determining an interference baseline ratio of the two interference loops;

the interference loop baseline ratio is the ratio of the lengths of the interference loop 2 baseline and the interference loop 1 baseline, and the ratio is not more than 1; the interference loop baseline ratio reflects the nonlinear distribution condition of array elements in a linear array, and the four-source back cross eye gain is as follows:

wherein, F₂Is the interference loop baseline ratio; the factor influencing the gain from the expression of cross-eye gain is the interference loop baseline ratio(ii) a The length of the base line of the interference loop 2 is arbitrarily valued within the total base line length; for a two-source reverse cross-eye jammer, under the premise that other parameters are not changed, the longer the antenna array baseline of the jammer is, the larger the angle measurement error of the monopulse radar caused by cross-eye interference is, and the antennas of the jammer system are arranged on two sides of a wing or a ship board so as to maximize the length of the antenna array baseline; according to the cross eye gain formula, under the condition of the determined signal amplitude phase relation, the larger the interference loop baseline ratio is, the larger the cross eye gain is, the linear relation is formed between the interference loop baseline ratio and the cross eye gain, and the parameter tolerance of the interference machine is looser at the moment;

for an Archimedes helical antenna, the relationship between the antenna aperture and the operating frequency band is taken as d_p2.5 λ, when kd > 1 is satisfied, two-antenna spacing requirements with sufficient isolation are obtained:

since the archimedean spiral antenna is a circular planar antenna, the requirement of the above formula is understood as that the distance between the edges of two adjacent antennas is greater than 10 times λ/(2 π), and then the minimum distance between the centers of the adjacent antennas is:

to reduce mutual interference between antennas, take d_min3 λ; three important conclusions are obtained according to the obtained minimum setting distance of the antenna:

the four-source non-uniform linear array inverse cross eye jammer adopts a flight carrier of an Archimedes spiral antenna, and the minimum setting distance of adjacent antennas is 3 times of wavelength;

the minimum application platform diameter of the flight carrier four-source line array inverse cross eye interference machine adopting the Archimedes spiral antenna is 9 lambda;

thirdly, the maximum interference baseline ratio adopted by the interference machine is as follows:

wherein d is_2maxLongest base line value used for interference loop 2, d_cThe length of a base line of the jammer antenna array is the base line value of the jammer loop 1;

step four: performing cross-eye interference on the monopulse radar in the viewing direction;

in the aircraft penetration stage, when the aircraft is irradiated by a monopulse detection tracking radar in the front view direction, the cross-eye jammer interferes the aircraft;

the four-source non-uniform linear array inverted cross eye jammer can effectively interfere with a monopulse radar by needing two paths of interference signals with approximately equal amplitudes and opposite phases; the amplitude ratio of two paths of interference signals in two interference loops is controlled within the range of (0.8,1.2), the phase difference is controlled within the range of (170 degrees and 190 degrees), so that the phase and difference monopulse radar angle measurement generates errors, even the target is unlocked, accurate aircraft angle information cannot be given, and effective defense can not be carried out on an oncoming aircraft.

Technical Field

The invention belongs to the technical field of radar electronic countermeasure, and provides a four-source non-uniform linear array back-crossing eye interference method based on a flight carrier based on available narrow space on a flight body, which is mainly used for preventing interference to the direction-finding performance of a monopulse radar in a penetration.

Background

The precise guided weapon becomes the most important hard killer weapon in a battlefield, has great advantages in the aspects of preventing an aerial flight body from suddenly and striking large-scale water surface facilities, and needs to implement effective interference on a detection tracking radar in order to ensure the tracking striking capability of the flight body.

At present, the monopulse angle measurement technology has the advantages of high angle measurement precision, strong anti-interference capability and the like, and is widely applied to the fields of target tracking and the like, and the monopulse technology is generally adopted by advanced tracking guidance radars. The interference monopulse radar once becomes a research hotspot and difficulty in the field of electronic warfare. The interference patterns of the monopulse radar mainly include towed decoy interference, cross polarization interference, cross eye interference and the like, wherein the cross eye interference is considered as the most effective interference pattern for interfering the monopulse radar. The cross-eye interference is an interference pattern capable of effectively resisting monopulse angular radar, belongs to a coherent interference system, has the advantages of high reliability, short system response time, long effective interference time, low life cycle cost and the like, and is widely concerned by domestic and foreign scholars in recent years.

The cross-eye interference is that by emitting two or more interference signals with approximately equal amplitude and 180-degree phase difference, the monopulse radar can be directed to a deviated target, and even the monopulse radar is out-of-lock in tracking. Cross-eye interference was first proposed in 1958 and has now been dominated by two-source and multi-source cross-eye interference over half a century of development. With the introduction of digital radio frequency memories and inverse antenna arrays with self-phasing characteristics, cross-eye interference techniques are implemented in engineering applications.

At present, the cross-eye interference technology is applied to the fields of anti-radiation flight body hitting of foundation radar, single pulse radar detection of airplane targets and the like, and the ground radar and the airplane are effectively protected. This is because ground-based radars and aircraft, when used as carriers, can provide a length of installation base line greater than 10m, and can meet the space requirements for effective implementation of two-source cross-eye interference. However, limited by the harsh parameter tolerances of conventional two-source cross-eye interference techniques, allows for flying objects such as: the limited cross-eye interference can not be realized by narrow space carriers such as unmanned aerial vehicles, small-sized airplanes and guided missiles, and the application of the cross-eye interference technology is limited. For example, when the aircraft is just performing the penetration of the monopulse detection radar, the cross section diameter of the cross-eye interference equipment which can be arranged is generally not more than 1m, which is far less than the use requirement of the traditional two-source cross-eye interference equipment. Aiming at the urgent need of small-sized flight body defense applications, the research on cross-eye interference technology with characteristics of multi-source, short baseline, non-uniform linear array distribution and the like is urgently needed. The array antenna structure is adopted to increase the number of antenna pairs, improve the degree of freedom of cross eye interference, obtain a gain larger than the traditional two-source cross eye interference, and reduce the requirement on parameter tolerance. The non-uniform linear array distribution can obtain larger cross-eye gain than uniform distribution under the condition of a certain source number, and the interference effect is enhanced.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a four-source non-uniform linear array reverse cross eye interference method for a monopulse angular radar based on a flight carrier.

In order to achieve the purpose, the invention adopts the following technical scheme:

a four-source non-uniform linear array back-crossing eye interference method based on a flight carrier is a four-source non-uniform linear array back-crossing eye interference method aiming at a monopulse angular radar based on the flight carrier, four Archimedes spiral antennas which are non-uniformly distributed are adopted to form a linear array antenna, the linear array antenna adopts a reverse structure, and cross eye interference is generated in a narrow space of the flight carrier, and the method comprises the following steps:

the method comprises the following steps: an Archimedes spiral antenna is adopted as a cross-eye jammer antenna;

the method is characterized in that cross-eye interference is implemented in a narrow space of an aircraft platform, the main problem is the arrangement problem of cross-eye interference machine antennas, the isolation between the antennas is required to be ensured so as to reduce mutual interference, and a larger interference loop baseline ratio is required to obtain a large cross-eye interference gain; the cross-eye jammer antenna adopts an Archimedes spiral antenna, has wide frequency band, circular polarization, small size and convenient embedding in a frequency band range of 100 MHz-50 GHz, and has stable directional diagram, axial ratio and input impedance on the frequency band;

step two: the single interference loop adopts a two-source reverse cross eye interference machine structure of a receiving and transmitting single antenna;

the reverse cross-eye jammer is a cross-eye jammer adopting a reverse antenna structure, a reverse antenna array consists of a plurality of paired antennas, and signals are transmitted in two directions; the reverse antenna has the self-phase-adjusting characteristic, has two paths of interference signals with approximately equal amplitudes and opposite phases, and can interfere the monopulse radar;

the reverse antenna has a phase difference exceeding the tolerance of system parameters in a self-compensating interference loop, and the adoption of the reverse antenna array is a necessary condition of a cross-eye jammer;

the four-source non-uniform linear array inverse cross eye jammer is provided with two jamming loops, and a single jamming loop adopts a two-source inverse cross eye jammer structure of a transmitting and receiving single antenna; the two paths of interference signals are subjected to power attenuation and phase delay introduced by the same transceiving antenna, circulator, feeder line, component and feeder line, and the parameter matching between the two paths of interference signals is not influenced, so that the length of the feeder line is selected at will;

step three: determining an interference baseline ratio of the two interference loops;

the interference loop baseline ratio is the ratio of the lengths of the interference loop 2 baseline and the interference loop 1 baseline, and the ratio is not more than 1; the interference loop baseline ratio reflects the nonlinear distribution condition of array elements in a linear array, and the four-source back cross eye gain is as follows:

wherein, F₂Is the interference loop baseline ratio; the factor influencing the gain from the expression of the cross-eye gain is the interference loop baseline ratio; the length of the base line of the interference loop 2 is arbitrarily valued within the total base line length; for a two-source reverse cross-eye jammer, under the premise that other parameters are not changed, the longer the antenna array baseline of the jammer is, the larger the angle measurement error of the monopulse radar caused by cross-eye interference is, and the antennas of the jammer system are arranged on two sides of a wing or a ship board so as to maximize the length of the antenna array baseline; according to the cross eye gain formula, under the condition of the determined signal amplitude phase relation, the larger the interference loop baseline ratio is, the larger the cross eye gain is, the linear relation is formed between the interference loop baseline ratio and the cross eye gain, and the parameter tolerance of the interference machine is looser at the moment;

for an Archimedes helical antenna, the relationship between the antenna aperture and the operating frequency band is taken as d_p2.5 λ, when kd > 1 is satisfied, two-antenna spacing requirements with sufficient isolation are obtained:

since the archimedean spiral antenna is a circular planar antenna, the requirement of the above formula is understood as that the distance between the edges of two adjacent antennas is greater than 10 times λ/(2 π), and then the minimum distance between the centers of the adjacent antennas is:

to reduce mutual interference between antennas, take d_min3 λ; three important conclusions are obtained according to the obtained minimum setting distance of the antenna:

the four-source non-uniform linear array inverse cross eye jammer adopts a flight carrier of an Archimedes spiral antenna, and the minimum setting distance of adjacent antennas is 3 times of wavelength;

the minimum application platform diameter of the flight carrier four-source line array inverse cross eye interference machine adopting the Archimedes spiral antenna is 9 lambda;

thirdly, the maximum interference baseline ratio adopted by the interference machine is as follows:

wherein d is_2maxLongest base line value used for interference loop 2, d_cThe length of a base line of the jammer antenna array is the base line value of the jammer loop 1;

step four: performing cross-eye interference on the monopulse radar in the viewing direction;

in the aircraft penetration stage, when the aircraft is irradiated by a monopulse detection tracking radar in the front view direction, the cross-eye jammer interferes the aircraft;

the four-source non-uniform linear array inverted cross eye jammer can effectively interfere with a monopulse radar by needing two paths of interference signals with approximately equal amplitudes and opposite phases; the amplitude ratio of two paths of interference signals in two interference loops is controlled within the range of (0.8,1.2), the phase difference is controlled within the range of (170 degrees and 190 degrees), so that the phase and difference monopulse radar angle measurement generates errors, even the target is unlocked, accurate aircraft angle information cannot be given, and effective defense can not be carried out on an oncoming aircraft.

Due to the adoption of the technical scheme, the invention has the following advantages:

the invention provides a four-source non-uniform linear array inverse cross eye interference method for a monopulse angular measurement radar. The invention can effectively interfere the monopulse angle measurement radar, provides effective protection for the sudden defense of small aircrafts such as a flying body, an unmanned plane and the like, and provides support for the practical application of the cross-eye interference technology.

According to the simulation result, the four-source non-uniform linear array inverted cross eye jammer of the flight carrier can form effective interference on a monopulse angle measuring radar, effectively protect an aircraft adopting the concomitant interference, effectively improve the penetration capability of the aircraft, and has important engineering application value.

Drawings

Fig. 1 is a schematic view of an aircraft structure.

Figure 2 is a schematic diagram of a four-source non-uniform linear array inverse cross-eye jammer mounted on a front cross-section of an aircraft.

Fig. 3 is a schematic diagram of a two-source inverted-cross-eye jammer transceiver single antenna configuration.

Fig. 4 shows a suitable scenario of the present invention, that is, a scenario in which an aircraft cross-eye jammer interferes with a monopulse radar.

Fig. 5 is a graph of cross-eye gain of a four-source inverse cross-eye jammer versus the amplitude ratio of interfering loop 2 with typical values for interfering loop 1 parameters.

Fig. 6 is a graph of cross-eye gain of a four-source inverse cross-eye jammer versus phase difference of interfering loop 2 for typical values of interfering loop 1 parameters.

Figure 7 is a graph of the cross-eye gain of the missile-borne four-source non-uniform linear array inverse cross-eye jammer and the amplitude ratio of the jamming loop 2 under the condition that the parameters of the jamming loop 1 are typical values when the jamming base line ratio is 0.775.

Fig. 8 is a diagram of the relationship between the cross-eye gain of the missile-borne four-source non-uniform linear array inverse cross-eye jammer and the phase difference of the jamming loop 2 under the condition that the parameters of the jamming loop 1 are typical values when the jamming base line ratio is 0.775.

FIG. 9 is a diagram showing the relationship between the monopulse radar angle measurement error and the induced bias distance caused by the missile-borne four-source non-uniform linear array reverse crossing eye interference and the amplitude ratio of the interference loop 2 when the interference base line ratio is 0.775 and the interference loop 1 parameter is a typical value.

FIG. 10 is a diagram showing the relationship between the monopulse radar angle measurement error and the induced offset distance caused by the reverse cross-eye interference of the missile-borne four-source non-uniform linear array and the phase difference of the interference loop 2 when the interference base line ratio is 0.775 and the parameters of the interference loop 1 are typical values.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1 to 10, a four-source non-uniform linear array back-crossing eye interference method based on a flight carrier is a four-source non-uniform linear array back-crossing eye interference method for a monopulse angular radar, and adopts four non-uniformly distributed archimedes helical antennas to form a linear array antenna, and the linear array antenna adopts an inverse structure to generate cross eye interference in a narrow space of an aircraft, and the method comprises the following steps:

the method comprises the following steps: an Archimedes spiral antenna is adopted as a cross-eye jammer antenna.

The method has the advantages that cross-eye interference is realized in a narrow space of an aircraft penetration platform, the main problem is the arrangement problem of cross-eye interference machine antennas, the requirement of isolation between the antennas is guaranteed, mutual interference is reduced, the interference loop baseline ratio is guaranteed to be as large as possible, and large cross-eye interference gain is obtained. The Archimedes spiral antenna has the advantages of wide frequency band, circular polarization, small size, capability of being embedded and the like in the frequency band range of 100 MHz-50 GHz, and has stable directional diagram, axial ratio and input impedance in a wide frequency band, so the Archimedes spiral antenna is used as the cross-eye jammer antenna of the flight carrier.

Step two: the single interference loop adopts a two-source reverse cross eye jammer structure of a transmitting and receiving single antenna.

The reverse cross-eye jammer is a cross-eye jammer adopting a reverse antenna structure, a reverse antenna array consists of a plurality of paired antennas, and signals can be transmitted in two directions. The reverse antenna has the self-phase-adjusting characteristic, the phase difference in an interference signal propagation loop is not needed to be considered, the radar position is not needed to be obtained in advance, and the single-pulse radar can be effectively interfered only by ensuring that the amplitudes of two paths of interference signals are approximately equal and the phases are opposite. Because the requirements of the cross-eye jammer on the amplitude ratio and the phase difference tolerance of the system parameters are very strict, the reverse antenna can perfectly self-compensate the phase difference exceeding the tolerance of the system parameters in the interference loop. Therefore, the adoption of the reverse antenna array is a necessary condition for the practical implementation of the cross-eye jammer.

The four-source non-uniform linear array inverse cross eye jammer is provided with two jamming loops, and a single jamming loop adopts a two-source inverse cross eye jammer structure of a transmitting and receiving single antenna. The two interference signals pass through the same transceiving antenna, circulator, feeder line, component and feeder line, and the power attenuation and phase delay introduced by the feeder line do not affect the parameter matching between the two interference signals, so the length of the feeder line can be selected at will. The interference machine with the structure has higher requirement on the transmitting and receiving isolation of the circulator, but is more suitable for practical application due to the excellent consistency characteristic.

Step three: an interference baseline ratio of the two interfering loops is determined.

The interference loop baseline ratio is the ratio of the length of the interference loop 2 baseline to the interference loop 1 baseline, and the ratio is not greater than 1. The interference loop baseline ratio reflects the nonlinear distribution condition of array elements in a linear array, and the interference performance of a cross-eye jammer can be influenced. The four-source inverse cross eye gain is:

wherein, F₂Is the interference loop baseline ratio. From the expression of cross-eye gainThe main factor affecting the gain level is the interference loop baseline ratio. The base length of the interference loop 2 can be any value within the total base length. For a two-source reverse cross-eye jammer, under the premise that other parameters are not changed, the longer the antenna array baseline of the jammer is, the larger the angle measurement error of the monopulse radar caused by cross-eye interference is, which is also the reason that the jammer system usually arranges antennas at two sides of a wing or a ship board so as to maximize the length of the antenna array baseline. According to the cross eye gain formula, under the condition of a determined signal amplitude phase relation, the larger the interference loop baseline ratio is, the larger the cross eye gain is, and the linear relation is formed between the interference loop baseline ratio and the cross eye gain, and at the moment, the parameter tolerance of the jammer is looser.

For an Archimedes helical antenna, the relationship between the antenna aperture and the operating frequency band is taken as d_p2.5 λ, when kd > 1 is satisfied, two-antenna spacing requirements with sufficient isolation are obtained:

since the archimedean spiral antenna is a circular planar antenna, in general, the requirement of the above formula can be understood as that the distance between two adjacent antenna edges is greater than 10 times λ/(2 π), and then the minimum distance between the center points of the adjacent antennas is:

for the convenience of theoretical analysis and practical application and for sufficiently reducing mutual interference among antennas, take d_min3 λ. Three important conclusions can be obtained according to the obtained minimum setting distance of the antenna, wherein firstly, the missile-borne four-source non-uniform linear array inverted cross eye jammer adopting the Archimedes spiral antenna has the minimum setting distance of the adjacent antenna being 3 times of wavelength; the diameter of the minimum application platform of the missile-borne four-source line array inverted cross eye jammer adopting the Archimedes spiral antenna is 9 lambda; thirdly, the maximum interference baseline ratio which can be adopted by the jammer is as follows:

wherein d is_2maxLongest baseline value usable for interference loop 2, d_cIs the baseline length of the jammer antenna array, i.e. the baseline value of the jammer loop 1.

Step four: and performing cross-eye interference on the monopulse radar in the viewing direction.

In the stage of the flying body defense, when the single-pulse detection tracking radar in the front-view direction irradiates, the cross-eye jammer interferes the single-pulse detection tracking radar.

The four-source non-uniform linear array inverse cross eye jammer designed by the invention can effectively interfere with the monopulse radar by only ensuring that the amplitudes of two paths of interference signals are approximately equal and the phases are opposite without considering the phase difference in an interference signal propagation loop and acquiring the radar position in advance. The amplitude ratio of two paths of interference signals in two interference loops is controlled within the range of (0.8,1.2), the phase difference is controlled within the range of (170 degrees and 190 degrees), errors are generated in the angle measurement of a phase and difference monopulse radar, even the target is unlocked, accurate flying body angle information cannot be given, and effective defense can not be carried out on a flying body.

The electronic interference equipment carried by the flight body has the cross-eye interference capability, and effectively interferes the detection radar of the opposite side, so that the flight position can not be accurately detected, and even the flight target can not be locked.

As shown in fig. 1, the structure of the flight object is schematically illustrated. The length of the flight body is generally about 4m, the width of the wing is 1-2 m, and the diameter is generally within 1 m. The cross-eye jammer can be arranged at two positions, namely, the forward circular section of the flight body is generally arranged in the head radome of the flight body and is used for interfering the radar in the front view direction; the other is the side surface of the flying body, which is used for interfering the detection radar in the side-looking direction and the interceptor of side-attacking. Aiming at the first condition, the invention carries out cross-eye interference on the monopulse detection radar in the viewing direction.

Figure 2 is a schematic diagram of a four-source non-uniform linear array inverse cross eye jammer. The interference machine comprises two interference loops, four sources in total, and feeder lines of the two interference loops have the same length. The Archimedes spiral antenna is used as a single receiving antenna and a single transmitting antenna, and four interference machine antennas are distributed on the diameter of the cross section of the flying body so as to obtain the maximum base length of the interference loop 1.

Fig. 3 is a schematic diagram of a two-source inverted-cross-eye jammer transceiver single antenna configuration. A single loop of the four-source non-uniform linear array inverse cross eye jammer adopts a two-source inverse cross eye jammer structure of a transmitting and receiving single antenna. The two interference signals pass through the same transceiving antenna, circulator, feeder line, component and feeder line, and the power attenuation and phase delay introduced by the feeder line do not affect the parameter matching between the two interference signals, so the length of the feeder line can be selected at will. The interference machine with the structure has higher requirement on the transmitting and receiving isolation of the circulator, but is more suitable for practical application due to the excellent consistency characteristic.

FIG. 4 shows a four-source non-uniform linear array inverse cross eye jammer interference ratio monopulse radar scene. The jammer is composed of 4 array elements, the antenna array elements 1 and 4 form a group of transceiving antenna pairs called as an interference loop 1, and the antenna array elements 2 and 3 form an interference loop 2. The signal flow of the interference loop 1 is as follows: the radar signal received by the antenna array element 1 is modulated by the signal and is sent out by the antenna array element 4; the radar signal received by the antenna array element 4 is sent out by the antenna array element 1 after being modulated, and the signal flow of the interference loop 2 is the same as the signal flow. r is the distance from the center of the radar antenna to the center of the jammer, namely the interference distance; d_pIs a phase comparison monopulse radar antenna aperture; theta_rThe turning angle of the radar visual axis relative to the center of the jammer, namely a radar turning angle; theta_cThe turning angle of the jammer relative to the center of the radar, namely the turning angle of the jammer; theta_eThe half opening angle of the jammer antenna array relative to the radar sight line; theta₂Is the half opening angle of the interference loop 2 relative to the radar line of sight; d_cIs the length of the antenna array base line of the jammer; d₂Is the interference loop 2 array element interval. In order to ensure that the lengths of the feeders of each loop are equal in the reverse structure of the antenna array, the existing documents are basically researched based on the equal-interval distribution of the array elements, but the equal interval of the array elements is difficult to ensure in practical use, and the non-uniformly distributed linear arrays have better performanceHas practical application value. The monopulse radar adopts a sum-difference angle measurement system, a sum channel is used for transmitting signals and receiving signals and normalizing echoes of a difference channel, and the difference channel is used for receiving the echoes and generating error signals.

Half opening angle theta of antenna array relative to radar line of sight_eGiven by the geometric relationship:

considering that the cross-eye jammer is in the far field of radiation of the monopulse radar antenna, i.e. r > d_cFor cross-eye jammers, r is generally more than or equal to 1km, d_cLess than or equal to 5m, and the approximation in the above formula is reasonable. Half opening angle theta of interference loop 1, 2 relative to radar line of sight₁、θ₂Comprises the following steps:

defining a factor F₂＝d₂/d_cIs the interference loop baseline ratio, the physical meaning is the ratio of the interference loop 2 baseline to the total antenna array baseline length, and F₂Less than or equal to 1. The interference loop baseline ratio reflects the nonlinear distribution condition of array elements in a linear array, and the interference performance of a cross-eye jammer can be influenced.

According to the interference scene shown in fig. 4, the included angles between the radar visual axis and the two array elements 1 and 4 of the interference loop 1 are respectively theta_r±θ₁Then the phase comparison single pulse radar sum channel and difference channel are in theta_r±θ₁The normalized gains in direction are respectively:

wherein P is_rFor radar antenna beams, P_r(θ_r±θ₁) For radar beam at theta_r±θ₁The gain in the direction, β, is the free space phase constant, β ═ 2 π/λ, λ is the wavelength.

According to the triangle addition formula, the following results are obtained:

wherein k is_s1And k is_c1Respectively as follows:

the normalized sum and difference channel gains can be simplified to:

suppose the amplitude ratio of the two directional signals in the interference loop 1 is a₁Phase difference of phi₁Then, the monopulse radar and the channel and difference channel echoes are respectively:

wherein P is_cFor jammer antenna beams, at θ_c±θ₁The beam gain in the direction is P_c(θ_c±θ₁)。

Definition ofBringing formula (14) into formula (15) yields:

wherein P is₁＝P_r(θ_r-θ₁)P_c(θ_c-θ₁)P_r(θ_r+θ₁)P_c(θ_c+θ₁)。

When two interference loops work simultaneously, the sum channel echo is:

the total difference channel echo is:

the single-pulse processor normalizes the difference channel echo by using the sum channel echo, and the derived single-pulse ratio is as follows:

whereinIn order to take the imaginary part of the operation,is the real part operation.

Single pulse indicating angle theta_iCan be obtained from the following relation:

theta when monopulse radar tracks a target_i＝θ_r(ii) a Theta when cross eye interference is present_i≠θ_r。

The cross eye gain is an important index for measuring the angle measurement error, and the formula (19) can be simplified according to the triangular approximation in the literature:

cos(2k_c1)＝cos[βd_pcos(θ_r)sin(θ_e)]≈1 (21)

when theta is_e＜＜βd_pThe above approximation holds true. At the same time, because of theta_n≤θ_e、r＞＞d_cThe following approximation can also be made:

the formula (21) and (22) are introduced into the formula (19), and the single pulse ratio can be simplified as follows:

wherein:

the four-source inverse cross-eye gain is defined as:

since four array elements correspond to two interference loops, the gain is G_c2. The single pulse ratio can be expressed as:

the first term of the monopulse ratio formula represents the beacon, indicating the true angle of the target, and the second term is monopulse angular error introduced by cross-eye interference. As can be seen from the equation (26), the magnitude of the angle measurement error and the cross-eye gain G_c2And half field angle theta of interference antenna_eIt is related. Theta_eIs determined by the length of the antenna base line of the jammer, and theta is determined after the length of the base line is determined according to the use requirement_eIs a fixed value. Therefore, the magnitude of the angle measurement error depends on the cross-eye gain. When the number of array elements is 2, the cross-eye gain of the two-source reverse cross-eye interference is the same, and the famous traditional cross-eye interference use condition is obtained: the two paths of interference signals are approximately equal in amplitude and opposite in phase.

Fig. 5 is a graph showing the relationship between the cross-eye gain of the four-source inverse cross-eye jammer and the amplitude ratio of the interfering loop 2 when the parameter of the interfering loop 1 is a typical value, and fig. 6 is a graph showing the relationship between the cross-eye gain of the four-source inverse cross-eye jammer and the phase difference of the interfering loop 2 when the parameter of the interfering loop 1 is a typical value. Drawing (A)5 and 6 show the gain of the uniformly distributed four-source linear array inverse cross eye jammer along with the two groups of amplitude ratio phase differences (a) of two interference loops₁,φ₁)、(a₂,φ₂) Compared with the gain of the traditional two-source cross-eye jammer under the same condition. Fig. 5 is a partial magnified view because the (1,185) curve corresponds to a cross-eye gain maximum that is too large for the other curves to be viewed. For convenience of calculation and representation, the signal amplitude ratio and cross-eye gain are both multiplied and dB form is not used. Two important conclusions can be obtained from the graph, namely, the cross eye gain of the four-source cross eye jammer is obviously larger than that of the traditional two-source cross eye jammer, and the interference intensity of the four-source cross eye jammer is larger than that of the two-source cross eye jammer; and secondly, the parameter tolerance of the four-source cross-eye jammer is superior to that of the traditional two-source cross-eye jammer, the interference parameters can be set in a wider range, and the requirement on the amplitude phase relation of interference antenna signals is not as strict as before. The four-source cross-eye jammer is more suitable for practical application than the traditional two-source cross-eye jammer due to the two characteristics, and has a better interference effect on a monopulse radar.

The four-source linear array reverse cross eye jammers which are uniformly distributed are adopted in the figures 5 and 6, simulation results show that the jamming effect is superior to that of the traditional two-source cross eye jammers, the parameter configuration is more flexible and convenient, and the four-source cross eye jammers have important practical application value. However, the conditions for uniform distribution are harsh for the carrier platform, especially for the flying object, and are difficult to guarantee strictly in the actual design. Meanwhile, a uniformly distributed linear antenna structure is not an optimal antenna structure for a multi-source linear cross-eye jammer. Therefore, the influence of the antenna distribution structure of the four-source linear cross-eye jammer on the jammer interference characteristic, namely the influence of the interference loop baseline ratio on the cross-eye interference characteristic, needs to be analyzed in depth.

Fig. 7 is a graph showing the relationship between the cross-eye gain of the four-source non-uniform linear array inverse cross-eye jammer and the amplitude ratio of the interference loop 2 when the interference baseline ratio is 0.775 and the relationship between the cross-eye gain of the four-source non-uniform linear array inverse cross-eye jammer and the phase difference of the interference loop 2 when the interference baseline ratio is 0.775 and the interference loop 1 parameter is a typical value. As can be seen from the expression of cross-eye gain, the main factor affecting the gain magnitude is the interference loop baseline ratio. The base length of the interference loop 2 can be any value within the total base length. For a two-source reverse cross-eye jammer, under the premise that other parameters are not changed, the longer the antenna array baseline of the jammer is, the larger the angle measurement error of the monopulse radar caused by cross-eye interference is, which is also the reason that the jammer system usually arranges antennas at two sides of a wing or a ship board so as to maximize the length of the antenna array baseline. According to the cross eye gain formula, under the condition of a determined signal amplitude phase relation, the larger the interference loop baseline ratio is, the larger the cross eye gain is, and the linear relation is formed between the interference loop baseline ratio and the cross eye gain, and at the moment, the parameter tolerance of the jammer is looser.

The method has the advantages that cross-eye interference is realized in a narrow space of an aircraft platform, the main problem is the arrangement problem of cross-eye antennas, the requirement on isolation between the antennas is required to be ensured, mutual interference is reduced, the interference loop baseline ratio is ensured to be as large as possible, and large cross-eye interference gain is obtained. Assuming that the distance between two antennas is d, the two antennas can be considered to have sufficient isolation when kd > 1 is satisfied, where k ═ 2 π/λ is the wavenumber. The Archimedes spiral antenna is taken as an example for analysis, has the advantages of wide frequency band, circular polarization, small size, capability of being embedded and the like in the frequency band range of 100 MHz-50 GHz, and has stable directional diagram, axial ratio and input impedance in a wide frequency band.

The relation between the antenna aperture and the working frequency band is taken as d_p2.5 λ, when kd > 1 is satisfied, two-antenna spacing requirements with sufficient isolation are obtained:

since the archimedean spiral antenna is a circular planar antenna, in general, the requirement of equation (27) can be understood as that the distance between two adjacent antenna edges is greater than 10 times λ/(2 π), and the minimum distance between the center points of the adjacent antennas is:

for the convenience of theoretical analysis and practical application and for sufficiently reducing mutual interference among antennas, take d_min3 λ. Three important conclusions can be obtained according to the obtained minimum setting distance of the antenna, namely, a four-source non-uniform linear array inverted cross eye jammer adopting an Archimedes spiral antenna is adopted, and the minimum setting distance of adjacent antennas is 3 times of wavelength; the diameter of the minimum application platform of the four-source line array inverted cross eye interference machine adopting the Archimedes spiral antenna is 9 lambda; thirdly, the maximum interference baseline ratio which can be adopted by the jammer is as follows:

wherein d is_2maxLongest baseline value usable for interference loop 2, d_cIs the baseline length of the jammer antenna array, i.e. the baseline value of the jammer loop 1.

The length of the taking aircraft is about 4m, the wing width is 1-2 m, and the diameter is within 1 m. Setting base length d of jammer antenna array in simulation_cAnd the working wavelength is 0.03m, and when the interference is carried out on the radar which works at the frequency point of 10GHz in the X waveband, the working wavelength of the interference machine is lambda. The distance between the cross-eye jammer and the monopulse radar is 1km, and the jammer and the radar are just opposite to theta_r＝θ_c0 deg.. Under the condition, the maximum interference baseline ratio F of the interference machine can be calculated_2max＝(d_c-6λ)/d_c＝0.775。

FIGS. 7 and 8 show the 15 exemplary disturbance loop 1 parameters (a) when the disturbance to baseline ratio is 0.775₁,φ₁) Next, the cross-eye gain and interference loop 2 parameter (a)₂,φ₂) The relationship of (1). It can be seen from the figure that, near the ideal parameter conditions of constant amplitude and inverse, the cross eye gain is large, and the cross eye interference effect is obvious. The cross-eye gain base is over a wide range of parameters of amplitude ratio (0.8,1.2), phase difference (170 deg., 190 deg.)The power factor is more than 10 times, which shows that the parameter tolerance of the four-source non-uniform linear array inverse cross eye interference machine is loose and convenient for practical engineering application. Comparing with the cross-eye gain performance curves of the cross-eye jammers uniformly distributed in fig. 5 and 6, it can be seen that when the baseline ratio is 0.775, the value of the cross-eye gain is increased and the cross-eye interference effect is enhanced under the same amplitude ratio and phase difference conditions.

Fig. 9 is a graph showing a relationship between a monopulse radar angle measurement error and an induced bias distance caused by four-source non-uniform linear array reverse cross eye interference and an amplitude ratio of an interference loop 2 when an interference baseline ratio is 0.775 and a parameter of an interference loop 1 is a typical value, and fig. 10 is a graph showing a relationship between a monopulse radar angle measurement error and an induced bias distance caused by four-source non-uniform linear array reverse cross eye interference and a phase difference of the interference loop 2 when the interference baseline ratio is 0.775 and a parameter of the interference loop 1 is a typical value. Fig. 9 and fig. 10 show the angle measurement error and the induced offset distance of the monopulse radar brought by the four-source non-uniform linear array inverse cross eye jammer. It can be seen from the figure that within the large parameter tolerance range of the amplitude ratio (0.8,1.2) and the phase difference (170 ° and 190 °), the cross-eye interference can cause the angle measurement error of the monopulse radar to reach more than 0.5 ° and the induced offset distance to reach more than 8.7m, which is very significant in the protection effect caused by the cross-eye interference for the flying object with the diameter generally within 1 m.