RU2699079C1 - Direction finding method and broadband direction finder for realizing said method - Google Patents

Abstract

FIELD: radio engineering and communication.

SUBSTANCE: invention relates to radio engineering and can be used in systems for monitoring radio environment in a complex or as an independent device. Method of direction-finding during space survey includes radiation and reception of wave from target, determination of phase shift between these waves, conversion of phase shift into control signal, which is proportional to angular position of target in each position of beam of radar station antenna, wherein a linearly polarized wave is emitted with an electric field vector lying in the direction-finding plane, passing through the dielectric material plate located at the Brewster angle relative to the wave coming from the target, for the electric vector lying in the plane of incidence, and the phase shift is determined between the wave from the target passing through the plate from the dielectric material and the wave reflected from it. Broader direction finder implementing the method comprises a generator connected through a switch with a receiving-transmitting antenna, located on a platform rotating in the direction finding plane, with a drive and a turning angle sensor, a phase shift meter between signals from the antenna output, connected to the target position angle computer, wherein at the centre of the platform there is a plate of dielectric material at Brewster angle relative to the wave emitted by the linearly polarized transceiving antenna, wherein its polarization plane is oriented such that the antenna electric field vector lies in the direction-finding plane coinciding with the falling wave incident plane from the target onto the dielectric material plate, and the linearly polarized receiving antenna receiving the reflected wave from the plate is fixed on the platform rigidly relative to the plate at twice the Brewster angle relative to the incident wave from the target.

EFFECT: high accuracy of angular direction-finding in a wide frequency band.

2 cl, 6 dwg, 2 tbl

Description

The invention relates to radio engineering and can be used in monitoring systems for the radio environment in the complex or as a stand-alone device.

Known amplitude method of direction finding (US 5541608 G01S 5/04, 07/30/1996, US 2427029, 04/10/1942). The disadvantage of the amplitude method of direction finding is that it does not allow to obtain high accuracy direction finding in a wide range of angles.

A known phase-finding method in which to achieve high accuracy requires a large number of bases and channels in the receiving device (US 5541608 G01S 5/04, 07/30/1996, US 2427029, 04/10/1942).

The disadvantage of the phase method of direction finding is that it does not allow to obtain high accuracy direction finding in a wide frequency range.

It is possible to combine (combine) these methods and achieve high accuracy in a wide range of angles with a small number of bases and channels and, therefore, with minimum weight and overall ratios of the radio direction finder. In the patent US 6061022, G01S 5/04, 05/09/2000, describes a device that implements the amplitude-phase method of direction finding.

The disadvantage of this method of direction finding is that it does not allow to obtain high accuracy direction finding in a wide frequency range.

Closest to the proposed is the method of phase direction finding (Leonov A.I., Fomichev K.I. Monopulse radar. M., due to "Soviet Radio"., 1970, 392 pp. (Pp. 6-7, 20-23 )), in which the signal from the target is received by the receiving antenna, and the phase shift between the signals at the output of the partial antennas varies depending on the direction of deviation of the target relative to the equal signal direction. This signal is directly used to control the position of the antenna system in the process of direction finding or in the process of automatically tracking the target. The quality of the direction-finding properties of the system is determined by the steepness of the direction-finding characteristic. For an ideal direction finder, a change in the phase shift within ± 90 degrees relative to the equal-signal direction should occur with the greatest possible slope.

The disadvantage of the presented solution is that for the high accuracy of determining the angular position of the target, it is necessary to realize a high slope of the direction-finding characteristic of the antenna system, which requires a high degree of identity of the partial diagrams of the direction-finding antenna unattainable in a wide frequency band when using two antenna systems combined into one direction finder.

The objective of the invention is to improve the accuracy of direction finding, expanding the frequency range, increasing the noise immunity of the direction finder.

The task is achieved by the fact that it is proposed:

1. The direction finding method during the space survey, including emission and reception of a wave from a target, determining a phase shift between these waves, converting the phase shift to a control signal proportional to the angular position of the target in each position of the beam of the radar antenna, characterized in that it is linearly polarized wave with an electric field vector lying in the direction-finding plane passing through a plate of dielectric material located at a Brewster angle relative to the wave coming from ate for the electric vector lying in the plane of incidence and the phase shift between the wave is determined from the target passing through a plate of a dielectric material and the wave reflected from it.

2. A broadband direction finder, comprising a generator connected via a switch, with a receiving and transmitting antenna, located on a platform rotating in the direction-finding plane, with a drive and a rotation angle sensor, a phase shift meter between signals from the output of the antennas connected to a target angle calculator, characterized in that a plate of dielectric material is installed in the center of the platform at a Brewster angle relative to the wave emitted by the linearly polarized transceiver antenna, and its plane of polarization and it is oriented so that the antenna’s electric field vector lies in the direction-finding plane, which coincides with the plane of incidence of the incident wave from the target onto the plate of dielectric material, and the linearly polarized receiving antenna receiving the reflected wave from the plate is mounted on the platform motionless relative to the plate at a double angle Brewster regarding the incident wave from the target.

The authors found that when a plane linearly polarized electromagnetic wave with an electric field vector lying in the plane of reflection is reflected from the dielectric plate, the angular dependence of the phase shift between the incident and reflected waves in the region of the angle of incidence close to the Brewster angle is 180 degrees (± 90 degrees) and the angular position of the “zero” phase point for an electrically thin plate does not depend on the frequency of the incident field. This angular dependence of the phase shift corresponds to the direction-finding dependence for artificially created antenna direction finders.

In FIG. Figure 1 shows the angular dependence of the phase shift between the reflected and incident waves when a plane wave is incident on a quartz ceramic plate with a dielectric constant (ε) ε = 3.4 near the Brewster angle for various losses in the material. From FIG. 1 it can be seen that, depending on the amount of losses in the material, various values of the gradient of the phase shift of the direction-finding characteristic are realized, which can be selected depending on the angle resolution and practical conditions for the direction finder implementation.

In FIG. Figure 2 shows the angular dependence of the phase shift between the reflected and incident waves upon the incidence of a plane wave on a fused silica wafer with ε = 3.81 without loss near the Brewster angle for various operating frequencies in the range from 1 to 30 GHz for a wafer thickness of one thirtieth length waves at 10 GHz. From FIG. 2 shows that the direction-finding characteristic is being formed, on the basis of which a broadband direction finder is created.

The source of angular information in this method is the angular dependence of the phase shift of the reflected wave on a plate of dielectric material near the Brewster angle.

Angular information is extracted in the process of measuring the phase shift between waves reflected from the target: incident or transmitted through the plate and reflected from the plate.

Three postulates of the conditions of monopulse radar on the formation of the direction finder are fulfilled.

The angular information is extracted as a ratio and does not depend on the absolute level of amplitudes of the received signals.

The measured value of the phase shift during the transition from positive to negative arrival of the wave changes to the opposite, since the angular dependence of the phase shift is symmetric with respect to the equal signal direction.

The angular dependence of the phase shift, as the direction-finding characteristic of the goniometric system, is an odd real function of the angle of arrival of the wave relative to the equal-signal direction, which coincides with the Brewster angle.

The reflected wave is used as the difference channel of a conventional direction finder to control the position of the antenna system during direction finding or in the process of automatic tracking.

The wave received by the transceiver antenna corresponds to the total channel of a conventional direction finder and is used not only as a reference channel, but also for target detection, as well as for measuring the distance to the target and its speed.

In FIG. 3 shows a broadband direction finder. On the platform 1, rotating in the direction finding plane, with the generator 2, a linearly polarized transceiver antenna 3 with an electric field vector lying in the direction finding plane is installed. In the center of the platform, perpendicular to the bearing plane, there is a plate of dielectric material 4, and a receiving linearly polarized antenna 5 with an electric field vector lying in the direction-finding plane and receiving the reflected wave from the plate of dielectric material is mounted on the platform motionless relative to the plate at a double angle Brewster regarding the incident wave from the target. When the detector 6 detects waves from the target, the position of the target is refined by the phase shift of the direction finder. The waves from the target through the switch 7 and from the output of the receiving antenna 5 are fed to the phase shift meter 8, from the output of which the signal proportional to the phase shift falls into the target position angle calculator, based on processor 9, in which, taking into account the data on the angular position of the platform, coming from the sensor of the angular position of the platform 10, determines the angular position on the target. The rotation of the platform is carried out by a controlled drive 11, and when tracking the target, the position of the platform is controlled by the error signal coming from the calculator of the angle of the position of the target or processor 9 U (α).

From the description of the device’s block diagram, it can be seen that it does not contain frequency-dependent or resonant devices limiting the direction finder operation in frequency, therefore it is possible to use such a measurement circuit for any frequency range, including the light.

In FIG. 4 is a block diagram of a platform with a geometric angular mutual arrangement of direction finder structural elements. A plate of dielectric material is installed in the center of the platform and is located at an angle α relative to the initial axis OX. The target is conditionally oriented at an angle β relative to the axis OX. When observing the target, the transceiver antenna A1 is fixedly fixed at a Brewster angle to the normal to the plate and at an angle of γ ₃ = α + 270-α _Br relative to the OX axis, and the receiving antenna A2 is also fixed stationary relative to the plate and receives the target signal reflected from the plate at an angle of Brewster and is located at an angle of γ ₂ = α + 90 + α _Br . When the platform rotates, the direction of the antenna A1 to the target occurs when the antenna orientation angles are equal to:

and the angle of direction to the target is β = α + 90-α _Br1 .

When the platform rotates, the point of intersection of the direction from the A1 antenna to the target with the plate may depart from the center of the platform, but the authors found that near the direction of direction finding to the target and at a significant distance from the center of the platform to the target, this deviation is insignificant and cannot affect the accuracy of angular determination target position.

When a wave is reflected from the target, the input from the phase 8 shift meter receives waves from the target: the transmitted wave and reflected from the plate 4. The direction to the target is specified by changing the phase shift between these waves.

Changes in the phase shift of the reflected wave in the region of the Brewster angle for a plate with a thickness of d = 3 mm made of quartz glass with a dielectric constant ε = 3.81 and air permeability ε _in = 1.00058, equal to α _Br = 62.8665 ang. deg, at a frequency of F = 10 GHz for various values of material losses are presented in FIG. five.

м для частоты F=10 ГГц.Table 1 defines the slopes for each of the angular dependencies of the phase shift change of FIG. 3 (S, (phase. Hail. / Ang. Hail.)), For which, based on the phase shift resolution of Δϕ = 2 deg, for different values of the tangent of the dielectric loss angle of the material at ranges RR, the resolving power was calculated

m for a frequency of F = 10 GHz.

From table 1 it is seen that with a decrease in the dielectric loss of the material of which the plate is made, the steepness of the phase characteristic of the direction finder increases and its resolution increases. To increase the accuracy of determining the angular position of the target, a dielectric material with minimal losses is selected, that is, with a minimum tangent of the dielectric loss angle, for which the maximum slope of the angular dependence of the phase shift of the reflected wave is realized as a direction-finding characteristic.

Changes in the phase shift of the reflected wave in the region of the Brewster angle for a plate with a thickness of d = 3 mm made of quartz glass with a dielectric constant ε = 3.81 and air permeability ε _in = 1.00058, equal to α _Br = 62.8665 ang. hail for material loss equal to tanδ = 0.00005 for various frequencies is shown in FIG. 6.

From FIG. Figure 6 shows that for different frequencies of the incident wave, the phase difference of the reflected wave in the vicinity of the Brewster angle is unchanged.

Table 2 defines the slopes for each of the angular dependences of the phase shift of FIG. 4 (S, (phase. Deg. / Ang. Deg.)), Phase for the Brewster angle and electric plate thickness in the region of the Brewster angle of the incident wave for different frequencies.

From table 2 it is seen that the steepness of the phase characteristic in the region of the Brewster angle for various frequencies varies slightly, and the phases of these dependences for the Brewster angle with the calculated error coincide with the value of the electric thickness calculated by the formula:

where f is the signal frequency,

c is the speed of light

d is the thickness of the plate of dielectric material,

ε is the dielectric constant of the plate of a dielectric material,

α _Br - the angle of incidence of the wave equal to the Brewster angle for the dielectric constant ε of the plate of a dielectric material.

Thus, the direction finding method and the broadband device, made according to the proposed technical solution, can improve the accuracy of the angular detection of the target when working in a wide range of frequencies.

Claims (2)

1. The method of direction-finding during the survey of space, including radiation and reception of a wave from the target, determining the phase shift between these waves, converting the phase shift into a control signal proportional to the angular position of the target in each position of the beam of the antenna of the radar station, characterized in that it emits linearly polarized wave with an electric field vector lying in the direction-finding plane passing through a plate of dielectric material located at a Brewster angle relative to the wave coming from target, for an electric vector lying in the plane of incidence, and the phase shift is determined between the wave from the target passing through the plate of dielectric material and the wave reflected from it. 2. A broadband direction finder, comprising a generator connected via a switch to a receiving and transmitting antenna, located on a platform rotating in the direction-finding plane, with a drive and a rotation angle sensor, a phase shift meter between signals from the output of the antennas connected to a target angle calculator, characterized the fact that a plate of dielectric material is installed in the center of the platform at a Brewster angle relative to the wave emitted by the linearly polarized transceiver antenna, and its plane of polarization oriented so that the antenna’s electric field vector lies in the direction-finding plane coinciding with the plane of incidence of the incident wave from the target onto the plate of dielectric material, and the linearly polarized receiving antenna receiving the reflected wave from the plate is mounted on the platform motionless relative to the plate at twice the Brewster angle relative to the incident wave from the target.

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