SU862083A1 - Method of measuring effective area of frontal dispersion of objects having cylindrical shape - Google Patents

Description

The invention relates to a radar measurement technique and can be used to determine the effective scattering area (EPR) forward in the mirror direction of cylinders with a variable radius of curvature.

A known method for determining the frontal EPR of objects based on its irradiation with an electromagnetic field, receiving and measuring the reflected field, in which the irradiation to receive the reflected field is performed using two antennas spaced apart by a certain distance 1.

The presence of two antennas complicated & t the device that implements the method.

The closest in technical essence and the achieved result to the present invention is a method for determining the effective forward scattering area, based on the irradiation of an object by an electromagnetic field, receiving and measuring the reflected field using two spaced transmitting and receiving antennas, the receiving antenna being located in the plane drop wave 2.

The disadvantages of this method are low accuracy and the need to use two spaced antennas - transmitting and receiving - provided that the requirement to locate is satisfied.

receiving antenna exactly at an angle equal to the angle of incidence of the wave. For convex cylinders with an arbitrary profile, the last condition is difficult to achieve with high accuracy, and even a slight non-observance of the equality of the angles of incidence and reflection when the transmitting and receiving antennas are oriented leads to a large EPR measurement error forward, especially with sharp diagrams

10 directivity of antennas.

The purpose of the invention is to increase accuracy while simplifying the measurement apparatus by using one (receiving-transmitting) antenna.

15 To achieve this goal, when measuring the effective forward scattering area of objects of cylindrical shape using a method based on the irradiation of an object with an electromagnetic field, receiving and measuring a scattered field, the field scattered backward of a corrugated metallized field is measured.

corrugation

period

and tall

film with

less than 0, where A. is the length of the working wave located on a plane, the normal to which forms with the direction of propagation of the irradiating electromagnetic field an angle equal to the angle at which the scattering area is determined, also measure the field scattered back by the same film , but located on the object under study, and judging by the ratio of the obtained values, an effective ploilad scatters the object forward.

The drawing shows a schematic diagram of a device that implements the proposed method.

The device contains a transmitter 1 connected through an antenna switch 2 with a receiving-transmitting antenna 3; the receiver 4 connected by the input to the switch 2, and the output to the indicator 5.

The device works as follows.

Pulses of high-frequency electromagnetic energy generated by the transmitter 1, through the antenna switch 2, enter the receiving-transmitting antenna 3, which irradiates the cylinder 6 covered with a wavy film 7. The same antenna receives the electromagnetic field reflected back from the corrugation of the film and the antenna switch 2 during pauses between the probing pulses, it supplies the reflected electromagnetic energy to the receiver 4 and further to the indicator 5, the readings of which are proportional to the intensity of the received signal.

The ability to determine the EPR forward in the mirror direction of a cylinder of an arbitrary profile for a incident polarized perpendicular polarization (vector E is perpendicular to the dip plane) across the field reflected back to the source from a cylinder covered with a wavy film with resonant corrugations is based on the fact that the sex is proportional.

The relative value of the EPR forward in the mirror direction for a given angle of incidence is obtained as the ratio of the field reflected back from a cylindrical body covered with a wavy film of a given area to the field reflected back from the same film located on a plane, or:

where T) is the relative value of the EPR forward in the mirror direction; O - EPR back cylinder covered

wavy film;

Og - EPR back wavy film located on the plane; but,. Od - measured values. To obtain absolute values of the EPR forward in the mirror direction of the cylinder of an arbitrary profile, it is necessary to calibrate the indicator bar 7 based on measurements on circular cylinders of various radii whose EPR forward in the mirror direction is known from the calculation.

The dimensions of the cylindrical bodies, for which the proposed method is valid, should be no less than 3-4 K, and the minimum radius of curvature of the cylinder should not be less than 1.5 I.

Fulfillment of these conditions will provide a measurement error not exceeding 10-15%.

The formula connecting the minimum radius of curvature with the angle of incidence f of the radio wave and its length is:

l

R.

sin f

The advantages of the proposed method in comparison with the known ones are that with its help it is possible to measure the EPR forward in the mirror direction of the cylinders of an arbitrary profile on a one-station radar installation, and not on a two-position one. This eliminates the use of a separate receiving antenna and laboriously accurate orientation of the receiving antenna at a target at an angle equal to the angle of incidence, i.e., the measurement process is simplified.

In addition, the elimination of the orientation of the receiving antenna to the target at an angle equal to the angle of incidence excludes the basic measurement error, especially with sharp antenna patterns.

Claims (2)

Invention Formula A method for measuring the effective forward scattering area of cylindrical objects based on the irradiation of an object electromagnetic field, reception and measurement of the scattered field, characterized in that, in order to increase accuracy while simplifying the measuring apparatus by using one (transceiver) antenna, the field scattered backward of the corrugated metalized X is measured NOI film with a period of corrugation - and a height of less than 0.1 A., where K is the working wavelength, located on a plane, the normal to which forms with the direction of propagation of the irradiating electromagnetic field an angle equal to the angle at which the scattering area is determined and also measured the field scattered back by the same film, but located on the object under study, and judging by the ratio of the values obtained, the efficiency of the area of the object scattered forward is judged. Information sources, taken into account during the examination 1. Shtager E. A., Chaevsky E. V. Scattering of waves on bodies of complex shape. M., “Owls. Radio, 1974, p. 9. 2. Handbook of radar ed. Skolnik, M., “Owls. Radio, 1976, p. 294 (prototype).