RU2488135C1 - Method of measuring radar cross-section of large objects in anechoic chamber - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: method, which involves irradiating a large object mounted on a rotary support and determining power of the reflected signals (P_refl) when the large object rotates about a vertical axis, further includes calibration when the large object is stationary at a moment in time when the projection of the large object on the irradiation side is closed by a radar absorbent screen and residual reflection is compensated for; a reference reflector with a known radar cross-section (EPR - σ_ref) is mounted in front of the radar absorbent screen and power P_ref, of the signal reflected from the reference reflector with a known radar cross-section (EPR - σ_ref) is determined and the radar cross-section of the large object is calculated using the formula: $${\sigma }_{refl}={\sigma }_{ref}\frac{P_{refl}}{P_{ref}}.$$

EFFECT: high measurement accuracy owing to one-time installation of the object in an anechoic chamber and performing calibration without removing the measurement object from the anechoic chamber.

1 dwg

Description

The invention relates to radar, in particular to radar measurements, and can be used in laboratory conditions using measuring systems with an anechoic chamber (BEC).

The measurement of the effective scattering surface (EPR) of large-sized massive objects (aircraft engines, small rockets, etc.) in an anechoic chamber is characterized by a large amount of preparatory work, one of which is installing the object on a rotary support device in the BEC working volume, its orientation relative to the direction radiation. For example, installing an aircraft engine takes 4 to 8 hours. Moreover, during the ESR measurements of the object, it must be periodically removed from the working volume and replaced with a reference reflector for calibrating the receiving path.

According to the requirements for the measurement, the time between the removal of the measurement object and replacing it with a reference reflector should be reduced to a minimum.

A known method of measuring the effective scattering area (EPR) of an object (Stager EA "Scattering of radio waves by complex bodies", M. "Radio and communication", 1986, p. 10, formula (1.8)), based on the use of a reference reflector with a known EPR (σ _et ). The essence of the method is that a probe signal is emitted, the power of the received signal reflected from the reference reflector (P _et ) with a known EPR (σ _et ) is measured, the power of the received signal reflected from the object whose EPR is to be determined (P _neg ) is measured also the distance to the reference reflector (R _e ) and the object (R). The ESR (σ) of the object is calculated by the formula

. $$\sigma ={\sigma }_{\mathrm{uh}t}\frac{R_{\mathrm{about}tR}R}{R_{\mathrm{uh}t}{R}_{\mathrm{uh}}}$$

.

The disadvantage of this method is the lack of measurement accuracy due to the alternate measurement of the EPR of the object and the EPR of the standard.

There is also a known measurement method selected for the prototype (TIIER, 1965, t.53, No. 8, p.1051), in which at either time either the measurement object or the reference reflector is irradiated. For this, the rotation device is made so that it can be installed on it the measurement object and the reference reflector at the same time. In this case, the measurement object and the reference reflector alternately fall into the service area.

The disadvantage of this method of measuring the EPR of objects is the low accuracy of the measurements.

The technical result of the claimed invention "Method for measuring the effective scattering surface of large-sized massive objects in an anechoic chamber" is to increase the accuracy of measurements due to a single installation of the object in an anechoic chamber and introducing standardization without removing a large-sized massive (CM) object from the anechoic chamber.

To achieve a technical result in the known method for measuring the EPR of CM objects (σ _neg ) in an anechoic chamber (BEC), including irradiation of the CM object installed on the rotary support device (OPU) and determining the power of the reflected signals (P _neg ) when the CM rotates around the vertical axes, additionally carry out standardization when the CM object is stopped at the moment when the projection of the CM object on the back wall of the BEC is minimal, for which the object from the irradiation side is closed with a radio-absorbing screen and compensate the residual Agen then set the reference reflector with a known ESR (σ _fl) before radioabsorbing screen and determine the signal power (P _fl) reflected from the reference reflector with a known ESR and the ESR calculated (σ _Neg) KM object BEC formula

. $${\sigma }_{\mathrm{about}tR}={\sigma }_{\mathrm{uh}t}\frac{R_{\mathrm{about}tR}}{R_{\mathrm{uh}t}}$$

.

The method of measuring the EPR of large-sized massive objects in the BEC is implemented by a device, a diagram of which is shown in the drawing.

The device includes:

1 - microwave antenna collimator;

2 - transmitting collimator irradiator;

3 - receiving irradiator of the collimator;

4 - mounting and alignment unit of the collimator irradiators;

5 - transmitting device;

6 - receiving device;

7 - slewing ring;

8 - electromechanical rotation system of a slewing ring;

9 - hook for hanging a reference reflector;

10 - control computing complex;

11 - anechoic chamber;

12 - reference reflector with known EPR;

13 - radar absorbing screen;

14 - large-sized massive (KM) object.

A KM object 14 is mounted on a rotary support device 7, a radio-absorbing screen 13 is mounted on the back of the KM object 14, a reference reflector with a known EPR 12 is hung in front of the screen, which is mounted using a nylon thread on a hook for hanging a reference reflector with a known EPR 9. Reception 3 and transmitting 2 illuminators of the collimator 1 are fixed to the attachment and adjustment unit of the irradiators of the collimator 4. The transmitting irradiator of the collimator 2 is connected to the transmitting device 5, the receiving irradiator of the collimator 3 is connected to the receiving device 6, the pivoting device 7 is connected mechanically to the electromechanical rotation system of the pivoting device 8. The transmitting device 5, the receiving device 6 and the electromechanical rotation system of the pivoting device 8 are connected to the control computer complex 10 and are located outside the anechoic chamber 11. the elements are located in the anechoic chamber 11.

A device that implements a method of measuring the EPR of large-sized massive objects, works as follows.

A KM object 14 is mounted on a rotary support device 7 in an anechoic chamber 11. A KM object 14 is irradiated by an antenna microwave collimator 1, which, in turn, is irradiated by a transmitting irradiator of the collimator 2, to which a microwave signal from a transmitting device 5 is supplied. The electromechanical rotation system is turned on slewing device 8. reflected from the rotating object CM signal P is received _Neg collimator microwave antenna 1 and then receiving collimator irradiator 3, the signal of which enters into a receiving e device 6 and is stored in the control computer complex 10. The control computer system 10 controls the operation of the transmitting device 5 and the operation of the electromechanical rotation system of the slewing ring 8. After a complete revolution of the KM object 14, the KM object stops at the moment of the minimum projection area of the KM object 14 on the back wall of the anechoic chamber 11. A radio-absorbing screen 13 is installed, residual reflections are compensated, a reference reflector is installed with the known EPR 12 and recording the signal (P _et ) reflected from the reference reflector with the known EPR 12 is received, and in the control computer complex 10 the EPR (σ _neg ) of the CM of the object is calculated by the formula:

. $${\sigma }_{\mathrm{about}tR}={\sigma }_{\mathrm{uh}t}\frac{R_{\mathrm{about}tR}}{R_{\mathrm{uh}t}}$$

.

The installation technology of the CM object has been tested, the devices used during installation are available and, therefore, the method of measuring the effective scattering surface of large-sized massive objects in an anechoic chamber meets the patentability condition “industrial applicability”.

Comparison of the claimed technical solution with the prior art in scientific, technical and patent documentation in the main and related sections reveals a technical solution that has the same characteristics as all the features contained in the claims proposed by the applicant, that is, the set of essential features of the claimed technical solution was not previously known, therefore, meets the condition of patentability "novelty."

Analysis of the known technical solutions in the art showed that the proposed method does not follow explicitly from the prior art for specialists, since technical solutions have not been identified that have features that match the distinctive features of the claimed invention and the influence of the distinctive features on the technical specified in the application is not confirmed. result. That is, the claimed technical solution has features that are not in the known technical solutions, and their use in the claimed combination of essential features makes it possible to obtain a new technical result.

Therefore, the proposed technical solution can be obtained only through a creative approach and is not obvious to a specialist in this field, that is, it has an "inventive step".

Claims (1)

A method for measuring the effective scattering surface (EPR) of large-sized massive (CM) objects in an anechoic chamber (BEC), comprising irradiating a CM installed on a rotary support device and determining the power of the reflected signals (P _OT ) when the CM is rotated around the vertical axis, characterized in that additionally carry out standardization when the CM object is stopped at the moment when the projection of the CM object on the back wall of the BEC is minimal, for which the CM object is closed from the irradiation side with a radio-absorbing screen and compensates residual reflection, then set the reference reflector with a known ESR (σ _fl) before radioabsorbing screen and determine the signal power (P _fl) reflected from the reference reflector with a known ESR (σ _fl), and calculating the ESR (σ _Neg) KM object by the formula :
$${\sigma }_{\mathrm{about}tR}={\sigma }_{\mathrm{uh}t}\frac{P_{\mathrm{about}tR}}{P_{\mathrm{uh}t}}$$

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