JP2019203786A - Antenna device and induction device - Google Patents

Abstract

To provide an antenna device capable of preventing deterioration in capability of being less detected without depending on a frequency even when the reflection characteristic of an antenna part has frequency selectivity.SOLUTION: An antenna device includes: a first reception unit 20 for receiving a first radar signal transmitted from an opposite radar; a calculation unit 30 for calculating a first frequency which is the frequency of the first radar signal; an active antenna 11 for radiating a second radar signal used for tracking a target into a space; a reflection control plate 8 disposed on a front surface of the active antenna 11 with an inclination; and a control unit 40 for controlling the inclination angle of the reflection control plate 8 on the basis of the first frequency calculated by the calculation unit 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna device having a reduced radar reflection cross-section (Radar Cross Section: RCS) and a guidance device equipped with the antenna device.

  When the guidance device tracks the target, it is necessary to point the antenna unit of the antenna device in the target direction in order to secure transmission power. However, when the antenna unit is directed in the target direction, much of the power of the radar signal transmitted from the counterpart radar device (hereinafter referred to as “partner radar”) returns to the direction of the counterpart radar. For this reason, there is a problem that the detectability detected by the partner radar is high, and in other words, there is a problem that the low detectability (LPI) is deteriorated.

  Patent Document 1 listed below discloses a technique for reducing RCS by arranging a metallic reflector having frequency selectivity with an inclination on the front surface of an antenna as a method for improving low detectability. .

Japanese Patent Application Laid-Open No. 61-084904

  However, since the reflection characteristic of the reflector arranged with the front surface of the antenna inclined has frequency selectivity, the value of RCS varies depending on the frequency of the radar signal transmitted from the partner radar. As a result, the technique of Patent Document 1 has a problem that the low detectability deteriorates depending on the frequency of the radar signal of the counterpart radar. For this reason, there is a need for a technique that can suppress the degradation of low detectability even when the reflection characteristics of the antenna section have frequency selectivity.

  The present invention has been made in view of the above, and suppresses the deterioration of low detectability without depending on the frequency even when the reflection characteristic of the antenna portion has frequency selectivity. An object is to obtain an antenna device that can be used.

  In order to solve the above-described problems and achieve the object, an antenna device for reducing RCS according to the present invention includes a first receiving unit that receives a first radar signal transmitted from a counterpart radar, A calculation unit that calculates a first frequency that is a frequency of the radar signal. The antenna device also includes an active antenna that radiates a second radar signal used for target tracking into space, and a reflection control plate that is disposed with an inclination on the front surface of the active antenna. The antenna device further includes a control unit that controls the inclination angle of the reflection control plate based on the first frequency calculated by the calculation unit.

  The antenna device according to the present invention has an effect that it is possible to suppress the deterioration of low detectability without depending on the frequency even when the reflection characteristic of the antenna unit has frequency selectivity.

The block diagram which shows the structure of the guidance device which concerns on embodiment The figure which shows typically the structure of the antenna part in the antenna device which concerns on embodiment The figure which uses for description of the reflection in the antenna part of the antenna device which concerns on embodiment The figure with which it uses for description of the RCS characteristic in the antenna part of the antenna device which concerns on embodiment The figure with which it uses for description of the RCS reduction effect in the antenna part of the antenna device which concerns on embodiment The block diagram which shows an example of the hardware constitutions which implement | achieve the function of the passive process part and target tracking part in embodiment The block diagram which shows the other example of the hardware constitution which implement | achieves the function of the passive process part in an embodiment, and a target tracking part The flowchart which shows the flow of the process in the control method of the antenna device which concerns on embodiment

  Hereinafter, an antenna device and a guidance device according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

Embodiment.
FIG. 1 is a block diagram illustrating a configuration of the guidance device according to the embodiment. The guidance device 1 according to the embodiment includes a first reception unit 20, a calculation unit 30, a control unit 40, a transmission / reception unit 50, an antenna unit 60, and a target tracking unit 70. The guidance device 1 is mounted on a flying body (not shown). The configuration of the first receiving unit 20, the calculating unit 30, the control unit 40, the transmission / reception unit 50, the antenna unit 60, and the target tracking unit 70 is a functional category, and differs from FIG. 1 due to the change of the functional category. A configuration may be adopted.

  As shown in FIG. 1, the first receiving unit 20 includes a passive antenna 3 and a passive receiving unit 4. The calculation unit 30 includes a frequency calculation unit 5. The control unit 40 includes an inclination angle correction unit 6 and an inclination angle control unit 7. The transmission / reception unit 50 includes an oscillation unit 9, a transmission unit 10, a transmission / reception switching unit 12, an active reception unit 13, and an analog-digital (Analog Digital: AD) conversion unit 14. The antenna unit 60 includes a reflection control plate 8 and an active antenna 11. The target tracking unit 70 includes a target detection unit 15 and a tracking processing unit 16. In the transmitting / receiving unit 50, the active receiving unit 13 and the AD converting unit 14 constitute a second receiving unit 50a. Moreover, the 1st receiving part 20, the calculation part 30, the control part 40, and the antenna part 60 comprise the antenna apparatus which reduces RCS which concerns on embodiment.

  Next, the function of each part which comprises the guidance apparatus 1 is demonstrated. In FIG. 1, the target 2 is a target object to be tracked. The target 2 includes a fixed target. Further, the target 2 may be a radar signal source, or a guidance device (not shown) that guides the target 2 may be a radar signal source.

  The passive antenna 3 receives the first radar signal transmitted from the opponent radar. The passive receiving unit 4 generates a signal obtained by frequency-converting and amplifying the first radar signal received by the passive antenna 3. The frequency calculator 5 calculates a first frequency that is the frequency of the first radar signal based on the signal output from the passive receiver 4. The tilt angle correction unit 6 calculates the tilt angle of the reflection control plate 8 for reducing the RCS of the antenna unit 60 based on the first frequency. Instead of calculating the tilt angle itself, a correction value of the tilt angle when controlling the tilt angle, that is, a change value from the current tilt angle may be calculated. The inclination angle control unit 7 transmits the calculated value or correction value of the inclination angle output from the inclination angle correction unit 6 to the reflection control plate 8.

  FIG. 2 is a diagram schematically illustrating the structure of the antenna unit in the antenna device according to the embodiment. As shown in FIG. 2, the reflection control plate 8 is disposed on the front surface of the active antenna 11 with an inclination of an inclination angle θ. Note that the front surface is a surface of the active antenna 11 on the side of the radio wave radiation direction. The reflection control plate 8 is a control plate that transmits or passes a signal in a specific frequency band and reflects a signal other than the specific frequency band in another direction. Examples of the reflection control plate 8 include a metal plate having a slot provided on the plate surface, or a frequency selection plate configured by stacking members having different transmission characteristics. In the reflection control plate 8, the tilt angle θ is controlled based on the tilt angle command output from the tilt angle control unit 7.

  Returning to FIG. 1, the oscillator 9 generates a second radar signal used for tracking the target 2. The second radar signal is given to the transmission unit 10. The second radar signal is generated using a reference signal generated inside the oscillation unit 9. The reference signal generated inside the oscillation unit 9 is given to the active reception unit 13 as a local signal.

  The transmission unit 10 amplifies the second radar signal and outputs it to the transmission / reception switching unit 12. The active antenna 11 radiates the second radar signal amplified by the transmission unit 10 to space. The active antenna 11 receives the reflected wave of the second radar signal reflected by the target 2. The transmission / reception switching unit 12 performs path switching between the second radar signal transmitted from the active antenna 11 and the second reception signal received by the active antenna 11. That is, when the second radar signal is radiated from the active antenna 11, the transmission / reception switching unit 12 electrically or mechanically connects the active antenna 11 and the transmission unit 10 and receives the target 2 received by the active antenna 11. When receiving the reflected signal from the active antenna 11, the active antenna 11 and the active receiver 13 are electrically or mechanically connected.

  The active reception unit 13 down-converts, that is, frequency-converts, the second reception signal received by the active antenna 11 by the local signal output from the oscillation unit 9. The active receiver 13 amplifies the frequency-converted signal and outputs the amplified signal to the AD converter 14. The AD conversion unit 14 converts the analog signal output from the active reception unit 13 into a digital signal and outputs the digital signal to the target detection unit 15 of the target tracking unit 70.

  The signal output from the AD conversion unit 14 includes signals other than the reflected signal from the target 2 to be tracked. For this reason, the target detection unit 15 detects a target signal including a reflection signal from the target 2 from the digital signal subjected to AD conversion. The tracking processing unit 16 calculates a target position, a target speed, and a target direction based on the target signal. The tracking processing unit 16 generates a guidance signal for guiding a flying object (not shown) guided by the guidance device 1 toward the target 2 based on information on the target position, target speed, and target direction in the target 2. .

  Next, the operation of the main part in the present embodiment will be described with reference to the drawings in FIGS. FIG. 3 is a diagram for explaining the reflection in the antenna unit of the antenna device according to the embodiment. FIG. 4 is a diagram for explaining the RCS characteristics in the antenna unit of the antenna device according to the embodiment. FIG. 5 is a diagram for explaining an RCS reduction effect in the antenna unit of the antenna device according to the embodiment.

  FIG. 3 shows a view of the antenna device shown in FIG. 2 viewed from the X direction. In FIG. 3, W1 indicates a path of an incident signal incident on the upper end portion of the reflection control plate 8, and W2 indicates a path of an incident signal incident on the lower end portion of the reflection control plate 8. Both incident signals incident on the paths W1 and W2 are incident signals incident from the front direction of the active antenna 11 from the direction orthogonal to the antenna surface 11a of the active antenna 11.

  Here, the length between the upper end portion and the lower end portion of the reflection control plate 8 is defined as d. At this time, the following phase difference φ occurs in one way between the path W1 and the path W2.

φ = (2π / λ) dsinθ
= (2πf / c) dsinθ
= Kfsin θ (1)

  In the above equation (1), c is the speed of light, λ is the wavelength of the incident signal, and f is the frequency of the incident signal. In the last formula modification, the coefficient “2πd / c” is set to “K”.

  As described above, there is a phase difference of φ in one way and 2φ in the reciprocation between the route W1 and the route W2. For this reason, the reflection control plate 8 exhibits a frequency characteristic in which the RCS changes depending on the frequency of the incident signal. FIG. 4 shows a situation where the incident signal and the reflected signal are strengthened and weakened according to the frequency of the incident signal.

  In FIG. 4, the solid line is the reflection characteristic when the inclination angle of the reflection control plate 8 is θ1, and the broken line is the reflection characteristic when the inclination angle of the reflection control plate 8 is θ2 (θ1 <θ2). . For example, the peak A of RCS when the tilt angle is θ1 is in the vicinity of 10.2 [GHz], and the peak B of RCS when the tilt angle is θ2 is near the frequency of 10.0 [GHz]. is there.

  As shown in FIG. 4, the reflection characteristic of the reflection control plate 8 has a shape in which peaks and valleys are formed depending on the frequency. Further, the phase difference φ due to the path difference changes depending on the inclination angle θ of the reflection control plate 8. For this reason, even at the same frequency, the RCS characteristic varies greatly depending on the inclination angle θ. In the present embodiment, these two properties are utilized so that the reflected signal on the reflection control plate 8 overlaps with the incident signal in the opposite phase in accordance with the frequency of the incident signal, so that most of the reflected signal is the other radar. The inclination angle θ of the reflection control plate 8 is controlled so as not to return to the side.

  In FIG. 5, the frequency characteristic of “with tilt angle control” is indicated by a solid line, and the frequency characteristic of “without tilt angle control” is indicated by a broken line. The frequency characteristic of “with inclination angle control” is the frequency characteristic when the inclination angle θ of the reflection control plate 8 is controlled in accordance with the inclination angle control according to the present embodiment, that is, the frequency of the incident signal. On the other hand, the frequency characteristic “without tilt angle control” is a frequency characteristic in which the tilt angle θ of the reflection control plate 8 is not fixed and the tilt angle θ of the reflection control plate 8 is fixed.

  In FIG. 5, the frequency f1 shown on the horizontal axis is the frequency of the incident signal. According to the example of FIG. 5, the RCS at the frequency f1 is at the point A1 located near the peak of the curve indicated by the broken line, and the RCS is large. On the other hand, when the tilt angle control is performed, as indicated by the solid line, the RCS at the frequency f1 is located at the null point of the reflection characteristic curve, and the RCS value Is getting smaller.

  In the example of FIG. 5, if the inclination angle of the reflection control plate 8 is controlled to be smaller than the inclination angle of the curve indicated by the broken line, the point A1 can be moved to the point B1. Moreover, if the inclination angle of the reflection control plate 8 is controlled to be larger than the inclination angle of the curve indicated by the broken line, the point A1 can be moved to the point B2. In either case, the C1 point that is the null point on the curve can be moved to the position of the frequency f1. From this, it can be seen that in order to reduce the RCS to a desired value or less, control for decreasing the inclination angle θ of the reflection control plate 8 may be performed, or control for increasing the RCS may be performed.

  Next, a hardware configuration for realizing the function of the guidance device 1 according to the embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a block diagram illustrating an example of a hardware configuration that implements the functions of the passive processing unit and the target tracking unit in the embodiment. FIG. 7 is a block diagram illustrating another example of a hardware configuration that implements the functions of the passive processing unit and the target tracking unit in the embodiment.

  When realizing the function of the guidance device 1 according to the embodiment, as shown in FIG. 6, a processor 200 that performs an operation, a memory 202 that stores a program read by the processor 200, and a signal input / output An interface 204 and a display 206 for displaying detection results may be included.

  The processor 200 may be an arithmetic unit such as an arithmetic device, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). In addition, the memory 202 includes a nonvolatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (registered trademark) (Electrically EPROM), Examples thereof include a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, and a DVD (Digital Versatile Disc).

  The memory 202 stores a program that executes the function of the guidance device 1 and a table that is referred to by the processor 200. The processor 200 exchanges necessary information via the interface 204, the processor 200 executes the program stored in the memory 202, and the processor 200 refers to the table stored in the memory 202, whereby the calculation unit described above is performed. 30, the process of the control part 40 and the target tracking part 70 can be performed. The calculation result by the processor 200 can be stored in the memory 202. Further, the processing result of the processor 200 can be displayed on the display 206. The indicator 206 may be provided outside the target tracking unit 70.

  Further, the processor 200 and the memory 202 shown in FIG. 6 may be replaced with a processing circuit 203 as shown in FIG. The processing circuit 203 corresponds to a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Note that some processing in the calculation unit 30, the control unit 40, and the target tracking unit 70 may be performed by the processing circuit 203, and processing not performed by the processing circuit 203 may be performed by the processor 200 and the memory 202.

  Next, a method for controlling the antenna device according to the embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing a process flow in the method of controlling the antenna device according to the embodiment.

  In FIG. 8, the calculation unit 30 measures the frequency of the first radar signal received through the passive antenna 3 (step S101). The control unit 40 evaluates the RCS characteristic at the measurement frequency (step S102). In the process of step S102, for example, the RCS of the reflection control plate 8 when the first radar signal enters from a direction orthogonal to the antenna surface 11a of the active antenna 11 is calculated. In order to shorten the processing time, the relationship between the frequency and the RCS is measured in advance, the minimum value of the RCS is obtained, and the obtained value is stored in the memory 202 shown in FIG. 6 as a table. Good. Further, when there is no RCS value corresponding to the measurement frequency in the table, it may be obtained by linear approximation, polynomial approximation or the like by interpolation calculation or extrapolation calculation.

  Returning to FIG. 8, the control unit 40 compares the RCS value calculated in step S102 with a threshold value (step S103). When the value of RCS is larger than the threshold value (step S103, Yes), the inclination angle control described above is performed (step S104), and the process is terminated. On the other hand, when the RCS value is equal to or less than the threshold value (No at Step S103), the inclination angle control is not performed (Step S105), and the process is terminated.

  In step S103, the case where the RCS value is equal to the threshold value is determined as “No”, but it may be determined as “Yes”. That is, when the RCS value is equal to the threshold value, the tilt angle control may be performed.

  Moreover, it supplements about said process. For example, in the process of step S101, when there are a plurality of passive signals received via the passive antenna 3, the inclination angle θ is selected such that the RCS value at each frequency is less than the threshold value.

  In addition, when it is not possible to select an inclination angle θ such that all RCS values are less than the threshold value for a plurality of passive signals, the RCS values are averaged in units of angle by which the inclination angle θ can be controlled. A simple inclination angle θ may be selected.

  Further, instead of the processing in step S103, the inclination angle control of the reflection control plate 8 may be performed so that the measurement frequency measured in step S101 is located at the position of the minimum value in the reflection characteristic of RCS. As shown in FIG. 5, there are a plurality of positions of local minimum values. For this reason, it is preferable to perform the tilt angle control so that the measurement frequency is located at the position of the nearest minimum value in the reflection characteristic of the RCS. In this way, the control amount of the tilt angle θ can be reduced, so that the tilt angle control with high responsiveness can be performed.

  As described above, the antenna device for reducing RCS according to the present embodiment has the first receiving unit that receives the first radar signal transmitted from the opponent radar and the frequency of the first radar signal. A calculation unit that calculates a first frequency, an active antenna that radiates a second radar signal used for tracking a target to space, a reflection control plate that is disposed with an inclination on the front surface of the active antenna, and a calculation unit Based on the calculated first frequency, a control unit that controls the inclination angle of the reflection control plate is provided, thereby calculating and calculating the first frequency of the first radar signal transmitted from the opponent radar. Since the inclination angle of the reflection control plate is controlled based on the first frequency, the RCS value can be controlled to suppress fluctuations in the RCS value. Thereby, even when the reflection characteristic of the antenna unit has frequency selectivity, it is possible to suppress the deterioration of low detectability without depending on the frequency.

  Note that the configurations shown in the above embodiments are examples of the contents of the present invention, and can be combined with other known techniques, and can be combined without departing from the gist of the present invention. It is also possible to omit or change a part of.

  DESCRIPTION OF SYMBOLS 1 Guide device, 2 Target, 3 Passive antenna, 4 Passive receiving part, 5 Frequency calculation part, 6 Inclination angle correction part, 7 Inclination angle control part, 8 Reflection control board, 9 Oscillation part, 10 transmission part, 11 Active antenna 11a antenna surface, 12 transmission / reception switching unit, 13 active reception unit, 14 AD conversion unit, 15 target detection unit, 16 tracking processing unit, 20 first reception unit, 30 calculation unit, 40 control unit, 50 transmission / reception unit, 50a Second receiving unit, 60 antenna unit, 70 target tracking unit, 200 processor, 202 memory, 203 processing circuit, 204 interface, 206 display.

Claims (5)

A first receiving unit for receiving a first radar signal transmitted from a counterpart radar;
A calculation unit that calculates a first frequency that is a frequency of the first radar signal;
An active antenna that radiates a second radar signal used for target tracking into space;
A reflection control plate disposed on the front surface of the active antenna with an inclination;
A control unit that controls an inclination angle of the reflection control plate based on the first frequency calculated by the calculation unit;
An antenna device comprising: The control unit calculates a radar reflection cross section of the reflection control plate when the signal of the first frequency calculated by the calculation unit is incident from a direction orthogonal to the antenna surface of the active antenna;
The antenna apparatus according to claim 1, wherein the inclination angle is controlled so that the calculated radar reflection cross-sectional area is smaller than a threshold value. The control unit calculates a reflection characteristic of a radar reflection cross section of the reflection control plate when the signal of the first frequency calculated by the calculation unit is incident on an antenna surface of the active antenna;
The antenna apparatus according to claim 1, wherein the inclination angle is controlled so that the first frequency is located at a position of a minimum value in a reflection characteristic of the radar reflection cross section.   The antenna device according to claim 3, wherein the minimum value in the reflection characteristic of the radar reflection cross-sectional area is calculated in advance by measurement. It has an antenna device given in any 1 paragraph of Claims 1-4,
A second receiver for receiving a reflected wave from the target of the second radar signal via the active antenna;
A target tracking unit that performs tracking of the target based on a received signal of the second receiving unit;
A guidance device comprising:

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