RU-1841400-C - Reflector antenna

Abstract

FIELD: antenna technology. SUBSTANCE: invention relates to antenna technology, in particular to antenna reflector mirrors intended for use in the centimeter and decimeter bands, and can be used both in radar station antennas and as receiving and transmitting antennas of communication lines. The claimed reflector of the mirror antenna is made in the form of a grid of parallel conductors placed on a frame made of a low-reflection material. The grid conductors are made in the form of cylindrical spirals of tightly wound wire, and the axes of the cylindrical spirals are parallel to the electric vector of the incident field, and the wire diameter d and the diameter of the cylindrical spirals α are related by the ratio 6d≤α≤0.05 λ max , where λ max is the largest wavelength of the working range. EFFECT: technical result is the creation of an antenna mirror having small reflecting properties outside the antenna working band, both in the area of small and in the area of large wavelengths, which increases the effectiveness of protecting the object on which the antenna with such a mirror is placed. 1 cl, 2 dwg

Inventors

• Egorychev Boris Aleksandrovich
• Nesterenko Mikhail Konstantinovich
• SMIRNOV NIKOLAJ NIKOLAEVICH

Assignees

• Акционерное общество "Центральный научно-исследовательский радиотехнический институт имени академика А.И. Берга"

Dates

Publication Date

20260506

Application Date

19770408

Claims (1)

1. A reflector antenna made in the form of a grid of parallel conductors placed on a frame made of low-reflecting material, characterized in that, in order to reduce the radar visibility of the reflector antenna outside the operating range, the grid conductors are made in the form of cylindrical spirals of tightly wound wire, wherein the axes of the cylindrical spirals are parallel to the electric vector of the incident field, and the diameter of the wire d and the diameter of the cylindrical spirals α are related by the ratio 6d ≤ α ≤ 0.05 λ max , where λ max is the longest wavelength of the operating range.

Description

The invention relates to antenna technology, in particular to antenna reflector mirrors intended for use in the centimeter and decimeter ranges. The invention can be used both in radar station antennas and as transmitting and receiving antennas for communication lines. Reflector antennas, containing mirrors and an irradiator, are widely known; they employ various types of mirrors with a surface in the form of a paraboloid of revolution, a parabolic cylinder, etc. (see G.N. Kocherzhevsky "Antenna-feeder devices", Moscow, 1972, E.Yu. Sheredko "Propagation of radio waves and antenna-feeder devices", Moscow, 1976). Also known are reflector antennas, in which the mirror surfaces are made in the form of solid or perforated metal sheets, grids of metal strips, a mesh of conductors, etc. (see Kuhn, “Microwave Antennas,” Shipbuilding, 1967, § 7.2.3). Typically, reflector antennas have a sufficiently large reflector surface area to ensure a given beamwidth, and therefore a large radar cross section. The use of such reflectors on various objects significantly increases their radar cross section (RCS) and reduces the effectiveness of measures taken to reduce their radar signature (applying a radar-absorbing coating, choosing a special shape that ensures low radar reflection). While it is fundamentally impossible to avoid large amounts of energy reflected from the antenna reflector within its operating range, it is quite possible to reduce the RCS of the antenna reflector outside its operating frequency band. For example, at wavelengths shorter than the operating wavelength, such a reduction in RCS can be achieved by using mesh mirrors with an appropriate mesh size. However, no methods or means are known for reducing the RCS of an antenna reflector at wavelengths greater than the maximum in the operating band. The aim of the proposed invention is to create an antenna mirror that has low reflective properties outside the antenna's operating band, both in the region of short and long wavelengths, which increases the protection efficiency of the object on which an antenna with such a mirror is located. The stated goal is achieved by the fact that the antenna mirror is made in the form of a grid of spiral-cylindrical conductors of solid (dense) winding, the diameter of which is selected depending on the length of the operating wave, from the condition of ensuring the reflection of electromagnetic waves in the operating range of the antenna. To explain the operating principle of the invention, the following drawings are attached: Fig. 1 shows the dependence of the effective scattering surface of a spiral-cylindrical conductor, related to the RCS of a linear conductor of the same length, as a function of the ratio of the spiral diameter to the wavelength; Fig. 2 shows a general view of a spiral-cylindrical conductor; Fig. 3 shows a diagram of the proposed antenna mirror. The following designations are used in the drawings and text: 1 - spiral-cylindrical conductor; 2 - low-reflective frame of the antenna mirror; 3 - reflective array of spiral-cylindrical conductors. The proposed device consists of a low-reflective mirror frame 2, made, for example, from a radio-transparent material or a radio-absorbing material, and spiral-cylindrical conductors 1 fixed to it, forming a reflective grating 3. The device's operation is based on the effect of anomalous reflection from spiral-cylindrical conductors, discovered and studied at the applicants' organization. The essence of this effect is as follows. Helically cylindrical conductors with a solid winding (turn tightly adjacent to turn) for certain ratios between the diameter of the spiral wire, the diameter of the spiral itself, and the wavelength can have a RCS many times lower than a linear conductor of the same diameter. As can be seen from the graph shown in Fig. 1, for the case where the spiral diameter α is approximately 6 times greater than the wire diameter d, already at values A spiral-cylindrical conductor has an ESR two orders of magnitude lower than a linear conductor made of wire of the same diameter. That is, at λ values 200 or more times greater than the spiral diameter, the latter reflects virtually no electromagnetic energy. As the wavelength decreases, the reflectivity of a spiral-cylindrical conductor, as can be seen in Fig. 1, increases, approaching, at values and EPR of a linear conductor. Reducing the RCS at wavelengths shorter than the operating range is achieved by using the sparse grid effect. As the wavelength decreases, the mirror's reflective grating becomes increasingly sparse, transmitting an increasing amount of incident energy. The combined use of the sparse grid effect and helical-cylindrical conductors allows for a mirror's RCS to peak at the operating point and fall off quite rapidly at longer and shorter wavelengths. The use of the invention will make it possible to significantly reduce the RCS of antenna mirrors, and consequently the objects on whic