RU2755338C1 - Waveguide-slot radiator - Google Patents

Abstract

FIELD: antennas.

SUBSTANCE: invention relates to antenna technology, particularly, to antenna apparatuses for directed radiation of an ultra high frequency signal, and can be used in development of meteorological, with a synthetic aperture, detection, tracking, weapon control radio location stations. The waveguide-slot radiator is comprised of parallel sections of rectangular waveguides, coupled in pairs by the outer wide walls thereof, and rectangular prisms. In one of the narrow walls of all sections of rectangular waveguides, radiating slots are made in form of a combination of an inclined slot and additional slots. Each of the inclined slots corresponds with two additional slots located at an angle to the inclined slot and on opposite sides thereof. Each of the ends of the inclined slot matches the end of one of the additional slots. The additional slots are parallel to the wide walls of the rectangular waveguide sections, providing lower sensitivity of the waveguide-slot radiator less to manufacturing errors. The rectangular prisms are placed between the radiating slots on the surface of the waveguide-slot radiator formed by the outer surfaces of the narrow walls of the rectangular waveguide sections. The faces of the rectangular prisms are perpendicular to the wide walls of the rectangular waveguide sections. On the face of the rectangular prisms parallel to the outer surfaces of the narrow walls of rectangular waveguide sections but not matching them, a flat radio-transparent fairing can be installed in form of a sheet of dielectric material with a low dielectric loss tangent value to protect the waveguide-slot radiator from external affecting factors.

EFFECT: technical result is the creation of a waveguide-slot radiator, the design whereof ensures reduced dependence of characteristics thereof on forming errors during manufacture and obtained characteristics close to theoretically possible.

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Description

The invention relates to antenna technology, in particular to waveguide-slot antenna arrays (WSCA) of directional radiation of a microwave signal, and can be used in the development of radar stations (radars) meteorological, with a synthetic aperture, detection, tracking, weapons control.

Among the antennas of the microwave range, a special place is occupied by waveguide-slot antenna arrays, which are used both as independent receiving and transmitting antenna systems, and as emitters of complex antenna devices. VSCHAR found numerous applications in radar, radio navigation and communication systems. The increased interest of developers of antenna technology in VSCHAR is due to the following advantages:

- the absence of protruding parts and compactness, which makes it possible to combine the emitting surface of the VSCHAR with the outer contours of the aircraft bodies, without introducing additional aerodynamic resistance;

- the possibility of relatively easy implementation of the required amplitude-phase distributions by regulating the connection of the radiating slots with the waveguide;

- high achievable level of instrumentation-efficiency, where instrumentation is the coefficient of surface utilization, efficiency is the coefficient of efficiency.

The most common types of radiating slits in a rectangular waveguide are: an inclined slit on a narrow waveguide wall, a longitudinal slit on a wide waveguide wall offset from its centerline, an inclined slit on a wide waveguide wall, a transverse slit on a wide waveguide wall offset from its centerline [ 1]. As a rule, the length of the radiating slots of the VSCAR is chosen in such a way that the slot is a purely active resistance and does not affect the phase velocity in the waveguide. The length of such a slit is called resonant. The electrical properties of inclined slots on a narrow wall of the waveguide are less dependent on frequency than other types of radiating slots; however, the decisive factor in choosing the type of radiating slots is the required polarization of the electromagnetic wave emitted and received by the antenna.

Known VSCHAR, in which to obtain the resonant length, the ends of the inclined slots on the narrow wall of the rectangular waveguide cover the waveguide [1]. To suppress the parasitic component of the field of the inclined slit in the narrow wall of the waveguide (polarized transversely to the waveguide), choke traps on the narrow walls of the waveguide or metal dividing blocks placed between the emitting slits can be used. The disadvantage of this technical solution is the impossibility of realizing such slots in a VSCHAR containing rectangular waveguides adjacent to each other.

The closest in technical essence to the proposed invention (prototype) is VSCHAR [2], which is a set of segments of rectangular waveguides, coupled in pairs with external wide walls. The emitting slits of this VSCHAR are located on one of the narrow walls of the sections of rectangular waveguides. Each of the emitting slits is made in the form of a combination of an inclined slit and two additional slits. Additional slots are located at right angles to the inclined slot and on opposite sides of it. Each of the ends of the inclined slot coincides with the end of the additional slot. On the outer surface of the narrow walls of rectangular waveguide segments, rectangular prisms are placed between the inclined slots, designed to suppress the parasitic component of the field of the emitting slots.

The conductivity of the radiating slit located on the narrow wall of the rectangular waveguide segment, which has the shape proposed in [2], is characterized by a significant steepness of the curve describing the dependence of the conductivity of the radiating slit on the angle of its inclination, which leads to an increased sensitivity of the waveguide-slit radiator to manufacturing errors, which is expressed in a significant deviation of its parameters from theoretically possible. The VSCHAR design described in [2] does not include a flat radio-transparent fairing designed to protect the waveguide-slotted radiator from external influencing factors. If such protection is necessary, flat radio-transparent fairings are usually used, installed in the near zone of the waveguide-slotted radiator. To reduce the effect on the external and internal characteristics of the waveguide-slotted radiator in the operating frequency range, in the simplest case, the flat radio-transparent fairing is made in the form of a single-layer dielectric structure with a small dielectric loss tangent of half-wave thickness or a thickness significantly less than the wavelength [3]. In the short-wavelength part of the centimeter range, and even more so in the millimeter wavelength range, it is not possible to manufacture a flat radio-transparent radome with an electrically small thickness. Due to a number of technological limitations (inhomogeneity of the dielectric properties of the fairing material in its volume, manufacturing errors), the presence of supporting structures and range properties, a flat radio-transparent fairing with a half-wave thickness inevitably degrades the characteristics of the waveguide-slotted radiator.

The aim of the present invention is to create a waveguide-slotted radiator of a technological design, which allows obtaining parameters close to theoretically possible, and, if necessary, equipped with a flat radio-transparent fairing, which provides reliable protection of the waveguide-slotted radiator from a wide range of both climatic and mechanical external factors. ...

The proposed slit-waveguide emitter contains parallel sections of rectangular waveguides, pairwise conjugated by their outer wide walls, and rectangular prisms. In one of the narrow walls of all sections of rectangular waveguides, radiating slits are made in the form of a combination of an inclined slit and additional slits. Each of the inclined slots corresponds to two additional slots, which are located to the inclined slot at an angle and on opposite sides of it. Each of the ends of the inclined slot coincides with the end of one of the additional slots. Additional slots are parallel to the wide walls of rectangular waveguide segments. Rectangular prisms are placed between the emitting slots on the surface of the waveguide-slotted radiator formed by the outer surfaces of the narrow walls of the rectangular waveguide segments. The faces of the rectangular prisms are perpendicular to the wide walls of the rectangular waveguide segments.

On the edges of rectangular prisms, parallel to the outer surfaces of the narrow walls of rectangular waveguide segments, but not coinciding with them, a flat radio-transparent fairing can be installed to protect the waveguide-slot radiator from external influencing factors, which is a sheet of dielectric material with a low value of the dielectric loss tangent.

When calculating the geometry of the proposed waveguide-slotted radiator, the conductivity of the radiating slots in the form of a combination of inclined slots and additional slots is determined based on the solution of Maxwell's equations by one of the known numerical methods (methods of finite domains or finite differences) or experimentally, taking into account the dimensions of rectangular prisms located between inclined slots, and the presence and dielectric properties of the material of the flat radio-transparent fairing. Taking these parameters into account makes it possible to obtain the characteristics of the waveguide-slotted radiator, which are close to theoretically possible.

FIG. 1 shows a general view of one of the embodiments of the proposed slotted waveguide emitter. In the narrow walls of pairwise conjugate sections of rectangular waveguides 1, radiating slits are made in the form of a combination of inclined slits 2 and additional slits 3. Rectangular prisms 4 are placed between the radiating slits on the surface of the waveguide-slotted radiator formed by the outer surfaces of the narrow walls of rectangular waveguides. The faces of the rectangular prisms are perpendicular to the wide walls of the rectangular waveguide segments. On the edges of rectangular prisms, parallel to the outer surfaces of the narrow walls of rectangular waveguide segments, but not coinciding with them, a flat radio-transparent fairing 5 can be installed.

In the transmission mode, an electromagnetic wave from the radar transmitting device, which is not part of the claimed waveguide-slotted emitter, through the diagram-forming radar device, which is not part of the claimed waveguide-slotted emitter, enters the inputs of the rectangular waveguide segments 1. Propagating along the rectangular waveguide segments 1, an electromagnetic wave excites emitting slits, consisting of a combination of an inclined slit 2 and additional slits 3. Further, an electromagnetic wave through the slots formed by rectangular prisms 4, and, if present, a flat radio-transparent fairing 5, is emitted into free space. Rectangular prisms 4 are designed to suppress the parasitic component of the field of the radiating slits.

In the receiving mode, the electromagnetic wave reflected from the target, having passed, if available, through a flat radio-transparent fairing 5 and emitting slots consisting of a combination of inclined slots 2 and additional slots 3, excites sections of rectangular waveguides 1 and through the radar diagram-forming device, which is not included in the composition of the inventive slotted waveguide emitter is fed to the input of the radar receiver, which is not part of the inventive slotted waveguide emitter.

FIG. 2 shows the graphs of the dependence of the normalized conductivity of a resonant radiating slot located on a narrow wall of a rectangular waveguide segment on the tilt angle for the shape of the radiating slot proposed in [2] (prototype) and in the present invention for a rectangular waveguide segment with a section of 13 × 6.5 mm. This dependence for a radiating slot having the shape proposed in the present invention has a significantly lower slope, which provides a lower sensitivity of the waveguide-slot radiator to manufacturing errors.

Sources of information

1. Rudolf Kühn. Microwave antennas: Responsible (scientific) editor M.P. Dolukhanov. - L .: Shipbuilding, 1967.

2. RF patent No. 2566644 dated 27.10.2015.

3. V.A. Capon. Radomes for microwave antennas (Radio engineering calculation and design). - M .: Sov. Radio, 1974.

Claims (2)

1. A waveguide-slotted radiator containing parallel sections of rectangular waveguides, pairwise conjugated by their outer wide walls, and in one of the narrow walls of the sections of rectangular waveguides, radiating slots are made in the form of a combination of an inclined slot and additional slots, each of the sloped slots corresponds to two additional slots , which are located to the inclined slot at an angle and on different sides of it, with each of the ends of the inclined slot coincides with the end of one of the additional slots, and rectangular prisms located on the surface of the waveguide-slot radiator formed by the outer surfaces of the narrow walls of rectangular waveguide segments , in which the radiating slots are made, between the radiating slots, and the edges of the rectangular prisms are perpendicular to the wide walls of the rectangular waveguide segments, characterized in that the additional slots are parallel to the wide walls of the rectangular waveguide segments. 2. The waveguide-slotted radiator according to claim 1, characterized in that on the edges of the rectangular prisms, parallel to the outer surfaces of the narrow walls of the rectangular waveguide segments, but not coinciding with them, a flat radio-transparent fairing is installed.

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