RU2332758C2 - Combined irradiator - Google Patents

Abstract

FIELD: physics; electricity.

SUBSTANCE: combined irradiator contains low-frequency round wave guide in which the polariser is mounted, and high-frequency round wave guide attached to low-frequency wave guide, high-frequency wave guide axis being perpendicular to low-frequency wave guide axes. The polariser is designed as selective screen inclined in wave guide and consisting of thin dielectric plate with dense lattice made of resonant dipole elements with frequency tuned to high-frequency range. The polariser contour is ellipse-shaped. Polariser dipoles are oriented perpendicular to low-frequency wave guide axes and at an angle of 45 degrees to electric field vector plane of a low-frequency wave. Electric field vector of high-frequency wave is parallel to dipoles. The irradiator generates low-frequency waves of circular polarisation and high-frequency waves of linear polarisation. High-frequency wave travels down on gradient junction formed by the polariser and low-frequency wave guide wall.

EFFECT: improved efficiency due to reduction of amplitude distribution and orientation diagram distortions.

2 cl, 8 dwg

Description

The invention relates to radio engineering and can be used in antenna technology, in particular in communications and satellite television.

Known waveguide polarizer, made in the form of a circular waveguide, in which a thin dielectric plate is placed, on the surface of which a thick lattice of dipoles is made [1].

The disadvantage of this polarizer is that it is located in a plane passing through the axis of the circular waveguide, and cannot be used as an additional device, for example, as a selective screen.

Known combined irradiator mirror antenna, consisting of two horns operating in different frequency ranges and irradiating a common selective screen located at an angle of 45 degrees with respect to horns [2]. The selective screen is made in the form of a lattice of dipoles tuned to the frequency of one of the ranges.

The disadvantage of this device is that the selective screen cannot be used as an additional device, for example, as a polarizer.

Known combined irradiator mirror antenna, consisting of two coaxial circular waveguides operating in different frequency ranges and embedded in each other [3]. To form the radiation pattern of the combined irradiator of the required width, an reflector is used to effectively irradiate the mirror antenna, and a polarizer is used to form a field with circular polarization.

The disadvantages of this irradiator are the design complexity, a significant longitudinal dimension and low efficiency due to the mutual influence of the waveguides. In the low-frequency range, the internal waveguide is transcendent, significantly distorting the amplitude distribution in the aperture of the external waveguide. And the directivity pattern of the internal waveguide is significantly distorted by the external waveguide.

The present invention is based on the task of creating a combined irradiator, which simplifies the design.

The problem is solved in that in a combined irradiator containing a circular low-frequency waveguide in which the polarizer is located, as well as a round high-frequency waveguide, according to the invention, the high-frequency waveguide is fixed to the side of the low-frequency waveguide wall, the polarizer being made in the form of a selective screen, located obliquely inside the low-frequency waveguide and consisting of a thin dielectric plate on which a dense grating is made from resonant elements, for example dipoles, tuned to the frequency of the high-frequency range. Additionally, an axisymmetric scattering lens is made in the low-frequency waveguide from the aperture, for example, in the form of a segment of the low-frequency waveguide with a dielectric cylindrical rod located in it.

This embodiment of the combined irradiator allows to simplify its design and increase efficiency.

The invention is illustrated by drawings, where:

- figure 1 shows a variant of a combined feed for an offset mirror;

- figure 2 shows embodiments of the polarizer;

- figure 3 shows a variant of the combined feed for an axisymmetric mirror;

- figure 4 shows a scattering lens and its radiation pattern.

электрического поля волны 13 низкочастотного диапазона в месте расположения пластины-перехода 3. Вектор

электрического поля волны 14 высокочастотного диапазона параллелен диполям 12. Между апертурой 15 волновода 1 и поляризатором 4 выполнен регулярный участок 16 волновода 1. Поляризатор 4 приклеен к стенке круглого волновода 1.In practice, combined irradiators are used to provide circular polarization in the low-frequency C-band (3.4 ... 4.2 GHz) and linear polarization in the high-frequency Ku-band (10.5 ... 12.75 GHz). The combined irradiator shown in Fig. 1 contains a round waveguide 1 of the low frequency range, a connecting flange 2, a dielectric transition plate 3 for a rectangular cross section, a polarizer 4 and a reflector 5 with a protective cover 6. A round waveguide 7 of the high frequency range is connected to the side of the waveguide 1 with flange 8. The axis 9 of the waveguide 7 is located, for example, perpendicular to the axis 10 of the waveguide 1. The polarizer 4 is inclined inside the waveguide 1 and is made in the form of a selective screen. Polarizer 4 is depicted in FIG. 2a and is a thin dielectric plate 11, on the surface of which a lattice made of resonant reflecting elements, for example parallel dipoles 12, is made by printing. The contour of polarizer 4 is an ellipse. The dipoles 12 of the polarizer 4 are oriented perpendicular to the axis 10 of the waveguide 1 and at an angle of 45 degrees with respect to the vector

the electric field of the wave 13 of the low frequency range at the location of the transition plate 3. Vector

the electric field of the wave 14 of the high-frequency range is parallel to the dipoles 12. Between the aperture 15 of the waveguide 1 and the polarizer 4, a regular section 16 of the waveguide 1 is made. The polarizer 4 is glued to the wall of the circular waveguide 1.

Consider the principle of operation of the irradiator. In the low-frequency range, the component of wave 13 parallel to dipoles 12 experiences a deceleration, while the component of wave 13, perpendicular to dipoles 12, passes practically without deceleration. The number and arrangement of dipoles 12 is selected in such a way that the polarizer 4 in the low-frequency range is matched and provides a differential phase shift of 90 degrees. The reflector 5 provides the formation of the radiation pattern required for effective irradiation of the offset mirror. In the high-frequency range, the dipoles 12 of the polarizer 4 are resonant and densely arranged to provide good reflectivity. The high-frequency wave 14 is emitted by the waveguide 7 and propagates through a smooth transition formed by the polarizer 4 and the wall of the circular waveguide 1. In phase 16 of the regular section of the waveguide 1, due to the forced refraction, the wave phase front is aligned, which leads to the formation of the radiation pattern required for effective irradiation offset mirror. A planar polarizer 4 was implemented, containing a lattice of 25 rows of dipoles, the total number of dipoles is 87. The level of polarization isolation at a frequency of 3.675 GHz was 25 dB.

To ensure the operation of the device in the Ku-band on circular polarization, the dipoles 12 of the polarizer 4 can be performed with a mutually perpendicular orientation [4], for example, as shown in Fig.2B.

A variant of the irradiator for an axisymmetric mirror is shown in figure 3 and differs in the implementation of the radiating part. To form the desired wide radiation pattern in the low frequency range, a reflector 17 is installed on the circular waveguide 1, having, for example, concentric grooves. In the high-frequency range, it is necessary to expand the radiation pattern using a scattering lens. An axisymmetric lens is a section of a regular waveguide 1, in which, from the aperture side 15 of the waveguide 1, a coaxially dielectric cylindrical rod 18 is mounted, fixed, for example, directly on the protective dielectric cover 19. In this case, two wave propagation channels are formed in the waveguide 1. One channel is a cylindrical rod 18, the wave in which experiences a deceleration of 180 degrees. The other channel is formed by the remaining air-filled space. Due to the antiphase annular portion of the field, a wider radiation pattern is formed in the aperture of waveguide 1 [5]. The field in the aperture of waveguide 1 in this case is consistent with the field formed in the focal plane of the mirror antenna when a plane wave is incident on it, which leads to an increase in the irradiator efficiency. On figa, b shows the scattering lens and its radiation patterns, having a table-like appearance and suitable for effective irradiation of an axisymmetric mirror. Curve 20 corresponds to the radiation pattern in the E-plane, curve 21 - in the H-plane. The rod 18 is made of fluoroplastic with a length of 35 mm and a diameter of 16 mm. The diameter of the waveguide 1 is equal to 61 mm In this case, the cylindrical rod 18 in the C-band is a resistance transformer, providing improved matching of the aperture 15 of the waveguide 1 with the free space.

The proposed solution also opens up the possibility of equipping existing C-band irradiators with Ku-band nozzles to expand their functionality. In this case, the circular waveguides of the existing C-band irradiator and the proposed irradiator are connected without using a connecting flange 2 and a transition plate 3.

The positive effect of the proposed device is to simplify the design by combining functions, in particular, a polarizer 4 in the form of a selective screen and a low-frequency waveguide 1 are used to channelize waves of both ranges, and the rod 18 is used as a scattering lens and as a resistance transformer. Another advantage of the irradiator is to increase its efficiency by increasing the receiving aperture and a more uniform amplitude distribution in it, which leads to an increase in the gain of the mirror antenna.

The proposed technical solution can be used in various antennas for communication systems and satellite television.

INFORMATION SOURCES

1. RF patent No. 2265922, Н01Р 1/161, 2004.

2. A.S. USSR No. 141515, H01Q 15/16, 1961.

3. US patent No. 4819005, CL. 343/786, 1986.

4. Eisenberg G.Z., Yampolsky V.T., Tereshin O.N., Antennas for VHF. - Part 2. M .: "Communication", 1977, p. 175, 176.

5. Collection. Antennas, issue 1 (92), 2005, pp. 59-62.

Claims (2)

1. Combined irradiator containing a circular low-frequency waveguide in which the polarizer is located, as well as a round high-frequency waveguide, characterized in that the high-frequency waveguide is connected to the low-frequency waveguide laterally, the axis of the high-frequency waveguide being perpendicular to the axis of the low-frequency waveguide, at this polarizer is made in the form of a selective screen, located obliquely inside the low-frequency waveguide and consisting it is made of a thin dielectric plate on which a dense lattice of resonant elements is made in the form of dipoles tuned to the high-frequency range and oriented perpendicular to the axis of the low-frequency waveguide and at an angle of 45 ° with respect to the plane of the electric field vector of the low-frequency wave. 2. The irradiator according to claim 1, characterized in that a scattering lens is mounted in the low-frequency waveguide on the aperture side, made in the form of a low-frequency waveguide segment with a coaxially dielectric cylindrical rod located therein.

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