RU2514128C2 - Mirror-horn antenna - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to antenna engineering. The mirror-horn antenna has a planar reflector in form of top, bottom and middle metal plates mounted parallel to each other, and a parabolic cylinder made of metal and mounted between the bottom and top plates and has ohmic contact with said plates, and its axis is perpendicular to the planes of said plates; the middle plate has an edge situated between the parabolic cylinder and its focus, wherein the gap between the edge and the parabolic cylinder has a constant width; a feed element mounted between the top and middle plates and made in form of at least one exciter and a wall made of metal and situated between the bottom and middle plates, perpendicular to said plates; the wall is also perpendicular to the plane of symmetry of the guide of the parabolic cylinder; the top and middle plates have straight edges which are perpendicular to the plane of symmetry of the guide of the parabolic cylinder and lie at a distance from the peak of the guide of the parabolic cylinder which is greater than the focal distance thereof; a radiator in form of two rectangular metal plates whose edges are joined to the straight edges of the top and middle plates, wherein the planes of the rectangular plates have an intersection line lying between the top and middle plates.

EFFECT: high efficiency and resolution of the mirror-horn antenna.

10 cl, 20 dwg

Description

The invention relates to antenna technology and can be used as an antenna of a radar or communication system.

Mirror antennas are widely used in various radio systems. Their advantages include simplicity of design, high coefficient of performance (COP), the possibility of realizing a high gain (KU), and the possibility of realizing radiation patterns of a special shape. These are cosecant shaped patterns, fan patterns, as well as total difference patterns, which are widely used in radar systems.

Known mirror antennas based on a mirror having the shape of a paraboloid of revolution and an irradiator located in the vicinity of the focus of the paraboloid (US Patent No. D409622, 1999, Parabolic antenna, Shigemi Inoue). The irradiator in the transmitting mode of operation of the antenna forms in the aperture of the mirror the amplitude-phase distribution (AFR) of the field necessary to create the desired shape of the pattern. The bottom of the irradiator should be chosen so that the energy does not "overflow" beyond the edges of the mirror, and the amplitude distribution has a given shape. The requirement of suppressing radiation outside the mirror minimizes power loss and increases the efficiency of the antenna as a whole. The shape of the amplitude distribution determines such an important quality indicator (PC) of the antenna as the level of the side lobes (UBL) of the beam.

An important class of mirror antennas are antennas with a fan beam. They are widely used in survey type radar systems. Such MDs have a main beam with substantially different widths in two orthogonal planes. In linear polarization antennas, these planes are often called the planes of vectors of electric and magnetic fields, or the planes of vectors E and N. For the implementation of a fan beam, the antenna mirror must have an unequal width in two planes, and therefore the irradiator must also have a beam with a significantly different width in indicated planes for optimal irradiation of the mirror surface. The greatest difficulty is the creation of an irradiator with a narrow beam, since for this its radiating aperture must have large electrical dimensions.

Most often, a horn with small aperture angles is used as the irradiator of the mirror antenna. If the radiating aperture of such a horn increases, then its length inevitably increases. As a result, the use of such a horn in a mirror antenna becomes ineffective, since it greatly obscures the mirror, which leads to a decrease in KU and an increase in SLL.

Additional difficulties arise when creating mirrored antennas with total-differential DNs. Such MDs are also widely used in radar to increase the accuracy of direction finding of a target. In antennas with a fan beam, the difference beam is used in a plane in which the width of the main beam is large. In this plane, the size of the irradiator is also large. The creation of differential DN is achieved by the use of two or more closely spaced irradiators (US Patent No. 7834803). The placement of two irradiators with large electrical dimensions further increases their negative impact on the bottom of the reflector antenna.

A mirror antenna is known in which a mirror having the shape of a parabolic cylinder is used (US Pat. No. 2,589,433). The mirror is placed between two parallel metal plates. In the vicinity of the focus is the irradiator. Thus, the irradiator does not radiate energy into free space, but into the region between two metal plates. Reflecting from the surface of the mirror, a cylindrical electromagnetic wave generated by the irradiator is converted into a plane wave. Parallel metal plates perform the function of a plane waveguide along which the wave propagates. At its edge, radiation occurs in free space. In this case, the breakage of a plane waveguide plays the role of a radiator of a mirror antenna. In an antenna of this type, a mirror forms a beam pattern in only one plane, in which the main beam has a smaller width. In the orthogonal plane, in which the main beam is wider, the beam pattern is formed by the emitter. Thus, the irradiator irradiates a mirror with large electrical dimensions. Therefore, it should have a wide DN and small size.

The disadvantage of this antenna is that it has a shading mirror irradiator. The size of the irradiator in this case is significantly smaller than the size of the irradiator antenna with a mirror in the form of a paraboloid of revolution, however, the area of the mirror in the form of a parabolic cylinder is also significantly smaller. Therefore, the ratio of the area of the irradiator and the mirror, which determines the degree of shading, remains at a high level, which leads to an increase in the SLL and a decrease in the CI.

The closest technical solution to the claimed mirror-horn antenna is an antenna (S.E. Bankov. Design and experimental study of the array of slot emitters. // Radio engineering and electronics, 2004, v. 49, No. 6, p. 701-706), containing a planar mirror, an irradiator and a radiator, the planar mirror being made in the form of upper, lower and middle metal plates that are installed parallel to each other, and a parabolic cylinder, which is made of metal, is installed between the lower and upper plates and has them galvanic contact, and its axis is perpendicular to the planes of the metal plates, the middle metal plate is installed between the upper and lower metal plates and has an edge located between the parabolic cylinder and its focus, and the gap between the edge and the parabolic cylinder has a constant width, the irradiator is installed between the lower and middle metal plates. The irradiator is made in the form of a flat horn, and the emitter is in the form of a flat slotted grating excited by a planar mirror.

The disadvantages of such an antenna include:

- a narrow band of operating frequencies, which is due to the dependence of the position of the main beam of the beam on the frequency arising from the phenomenon of frequency scanning inherent in gratings with sequential excitation;

- high UBL in the plane of the vector H is determined by the amplitude distribution of the horn wave and cannot be reduced below the level of - (18-20) dB, which is insufficient for many practical applications;

- the impossibility of creating a fan pattern with a large ratio of the width of the main beam in two planes due to a decrease in its efficiency in this case.

The present invention is aimed at obtaining a technical result, expressed in the expansion of the operating frequency band, in reducing the UBL of the beam, the formation of fan-shaped beam with a large ratio of the width of the main beam in two orthogonal planes, as well as the creation of total-difference beam in two orthogonal planes. The technical result obtained is expressed in an increase in efficiency and an increase in the resolution of the horn-mirror antenna.

The proposed mirror-horn antenna, comprising a planar mirror, an irradiator and a radiator, wherein the planar mirror is made in the form of upper, lower and middle metal plates that are mounted parallel to each other, and a parabolic cylinder, which is made of metal and installed between the lower and upper plates, and has galvanic contact with them, and its axis is perpendicular to the planes of these plates, the middle plate is installed between the upper and lower plates and has an edge located between the parabolic cylinder and its focus, and the gap between the edge and the parabolic cylinder has a constant width, the irradiator is installed between the lower and middle plates. A feature of the invention is the solution of the following tasks:

- extension of the working frequency band;

- reduction of UBL DN;

- the formation of a fan-shaped pattern with a large ratio of the width of the main beam in two orthogonal planes;

- the creation of total-difference MD in two orthogonal planes.

These problems are solved due to the fact that in order to reduce the level of the side lobes of the radiation pattern and to create a fan-like radiation pattern with a large ratio of the width of the main beam in two orthogonal planes, the irradiator is made in the form of at least one pathogen and a wall made of metal and installed between the lower and middle plates perpendicular to them, the wall is also installed perpendicular to the plane of symmetry of the guide of the parabolic cylinder, the upper and middle plates are made with straight edges perpendicular to the plane of symmetry of the guide of the parabolic cylinder and located at a distance from the top of the guide of the parabolic cylinder exceeding its focal length, the emitter is made in the form of two rectangular plates made of metal, the edges of which are connected with the straight edges of the upper and middle plates, and the plane rectangular plates have a line of intersection located between the upper and middle plates.

Additional options for the implementation of the mirror-horn antenna. In an additional embodiment, in order to improve its coordination, the pathogen is made in the form of a pin, which is made of metal and installed between the lower and middle plates perpendicular to it without galvanic contact with the indicated plates and the length of the transmission line, a concentrated capacitor is included in the gap between the middle plate and the pathogen, the transmission line has an inner end connected by a central conductor to a pin through an opening in the bottom plate, and an outer end forming the antenna output, the cut-off screen transmitting a SRI galvanic contact with the bottom plate.

In an additional embodiment, which provides increased convenience for mounting the antenna, the irradiator is made with one exciter in the form of two tapes and a segment of the transmission line, the tapes are made of metal and have galvanic contact with each other, their axes are located at right angles to each other, and the axis of one tape located parallel to the wall and perpendicular to the plates and connected to the upper plate through a capacitor, and the axis of the other tape is perpendicular to the wall and does not have galvanic contact with it, the segment of the transmission line has an internal the end connected by the central conductor to the tape, the axis of which is perpendicular to the wall, through an opening in the specified wall, and the outer end, which forms the antenna output, and the screen of the transmission line segment has galvanic contact with the wall.

In an additional embodiment, in order to expand the functionality, the irradiator is made with two pathogens, and these pathogens are located symmetrically relative to the plane of symmetry of the guide of the parabolic cylinder, and the outer ends of the segments of the transmission lines of the pathogens form two antenna outputs.

In an additional embodiment, in order to reduce side lobes in the plane of the magnetic field vector, an in-phase power divider is introduced into the irradiator into two equal parts, the lateral shoulders of which are connected to the outer ends of the segments of the transmission lines of pathogens.

In an additional embodiment, in order to form a sum-difference radiation pattern in the plane of the electric field vector, a hybrid connection and an additional planar mirror, an additional irradiator and an additional radiator identical to the planar mirror, irradiator and radiator and located symmetrically with respect to the plane of symmetry which is parallel to the plates a planar mirror, and the total-differential outputs of the hybrid connection are connected to the central inputs rows inphase power divider into two equal parts of basic and additional irradiators.

In an additional embodiment, in order to reduce the level of side lobes in the plane of the electric field vector, the first and second additional rectangular plates are introduced respectively into the main and additional emitters symmetrically with respect to the plane of symmetry parallel to the planar mirror plates, the two edges of the first additional rectangular plate are parallel to the straight edges of the middle and the upper plates, one of these edges being located between the middle and upper plates, and the other the edge is located in a plane passing through the edges of rectangular plates that are not connected to the middle and upper plates.

In an additional embodiment, in order to form a total-difference radiation pattern in the plane of the magnetic field vector, a hybrid connection is introduced into it, the total-difference outputs of which are connected to the external ends of the segments of the transmission lines of pathogens.

In an additional embodiment, in order to form a total-difference radiation pattern simultaneously in the plane of the vectors of electric and magnetic fields, an additional planar mirror, an additional irradiator and an additional radiator identical to the planar mirror, irradiator and radiator and located symmetrically with respect to the plane of symmetry which is parallel to the plates are inserted in the directional antenna planar mirror, also in the directional antenna introduced diagram-forming circuit, which EET four sum-difference output and at least three inputs, a sum-difference outputs are connected to the outer ends of the transmission line segments pathogens irradiator and additional illuminator.

Figure 1-3 shows one of the possible embodiments of a mirror horn antenna. Figure 1 presents a General view of a mirror-horn antenna in two projections. The horn-mirror antenna contains an irradiator (1), a planar mirror (2) and an emitter (3). In Fig.2 is a section A-A ′ of a mirror-horn antenna, and in Fig.3 is a section B-B ′. From figure 2, 3 it is seen that the planar mirror (2) is made in the form of an upper plate (4), a lower plate (6) and a middle plate (5), which are made of metal and mounted parallel to each other, and a parabolic cylinder (7 ), which is made of metal, is installed between the lower plate (4) and the upper plate (6) and has galvanic contact with them, and its axis is perpendicular to the planes of the plates (4, 5 and 6), the middle plate (5) is installed between the upper plate (4) and bottom plate (6). The irradiator (1) is made in the form of a pathogen (8) and a wall (9) made of metal and installed between the lower plate (4) and the middle plate (5) perpendicular to it, the wall (9) is also installed perpendicular to the plane of symmetry of the guide of the parabolic cylinder ( 7). The emitter (3) is made in the form of two rectangular plates (10) and (11), the edges of which are connected with the straight edges of the upper plate (6) and the middle plate (5), and the planes of the rectangular plates (10), (11) have an intersection line located between the upper plate (6) and the middle plate (5). The middle plate (6) has an edge (12) located between the parabolic cylinder (7) and its focus F, and the gap (13) between the edge (12) and the parabolic cylinder (7) has a constant width.

Consider the operation of a horn antenna. Since the antenna is a reciprocal device, it can be equivalently analyzed in the transmitting and receiving modes. Consider the operation of the antenna in transmitting mode.

, где k - волновое число свободного пространства, a ε - относительная диэлектрическая проницаемость среды внутри ПВ. В нашем случае она равна единице. Т-волна может распространяться в любом направлении в плоскости ПВ. Поэтому возбудитель (8) возбуждает внутри ПВ спектр Т-волн, формирующих поле внутри волновода. Это поле, имеющее характер цилиндрической волны, можно описать по аналогии с излучением в свободное пространство с помощью ДН D(θ), которая является функцией угла θ (см. фиг.4).In this case, the signal from an external source is supplied to the input of the irradiator (1), which contains the pathogen (8) and the wall (9). Together, they form an antenna that radiates electromagnetic energy into the space between the bottom plate (4) and the middle plate (5). The structure formed by two parallel plates of metal, in the microwave technique, is called a plane waveguide (PV). If the PV height h is less than half the wavelength in the medium filling it, then one wave propagates in it, having a single component of the electric field perpendicular to the plates forming the PV. This wave is called the T-wave. Its propagation constant γ is

, where k is the wave number of free space, and ε is the relative dielectric constant of the medium inside the PV. In our case, it is equal to unity. T-wave can propagate in any direction in the plane of the PV. Therefore, the pathogen (8) excites inside the PV the spectrum of T-waves that form the field inside the waveguide. This field, which has the nature of a cylindrical wave, can be described by analogy with radiation into free space with the help of a beam D (θ), which is a function of the angle θ (see Fig. 4).

The pathogen pathway (8) depends on the distance to the metal wall (9). Approximately it can be described as a bottom hole of a linear source located near a metal screen [1]

The phase center of the DN lies at the origin, which is located on the surface of the metal wall (7).

There is no radiation in the region | θ |> π / 2, since its penetration into this region is prevented by the wall (7). Thus, all the energy emitted by the pathogen propagates along the PV in the direction of the edge (12) of the middle plate (5). The gap (13) between the edge (12) and the parabolic cylinder (7) has a constant value near any point on the guide of the parabolic cylinder (7). The gap (13) plays the role of a coupling element that provides energy transfer from the region between the lower plate (4) and the middle plate (5) to the region between the middle plate (5) and the upper plate (6). The specified area is also the PV, which is located above the PV formed by the lower plate (4) and the middle plate (5). We call these PV upper and lower.

The width of the gap (12) is selected so that the reflection coefficient in the lower MF would be minimal. It was shown in [2] that the correct choice of the gap (12) ensures good coordination of the coupling element.

. Величина угла падения зависит от угла θ: φ=φ(θ). В указанной выше работе показано, что выбор зазора (12) обеспечивает коэффициент отражения R в нижний ПВ для всех углов падения на уровне, меньшем -20 дБ в широкой полосе частот. На фиг.6 показана частотная зависимость модуля коэффициента отражения R, полученная для ПВ высотой 5 мм при ширине зазора 3 мм. Кривая 1 соответствует нормальному падению волны, а кривая 2 - падению под углом 30°.The cylindrical wave created by the pathogen (8) at a sufficiently large distance from the origin can be represented in the approximation of geometric optics as a system of rays emanating from the phase center of the MD located at the origin. The incidence of one of these rays on the edge (12) is shown in Fig.5. Since the gap between the edge (12) and the parabolic cylinder (7) does not change along the edge, the edge (12) has a shape close to a parabola. Therefore, the beam falls on it at a certain angle φ between the beam and the normal to the edge

. The angle of incidence depends on the angle θ: φ = φ (θ). In the aforementioned work, it was shown that the choice of the gap (12) provides the reflection coefficient R in the lower MF for all incidence angles at a level less than -20 dB in a wide frequency band. Figure 6 shows the frequency dependence of the modulus of the reflection coefficient R obtained for a PV with a height of 5 mm with a gap width of 3 mm. Curve 1 corresponds to the normal incidence of the wave, and curve 2 to the incidence at an angle of 30 °.

The energy transfer to the upper PV from the lower is characterized for each beam by a transmission coefficient T, which, by virtue of the energy conservation law, is modulo close to unity. Its phase weakly depends on the angle of incidence φ. Therefore, the phase distribution of the field in the upper MF is determined mainly by the shape of the edge (12), as well as by the location of the focus F of the parabolic cylinder (7) relative to the phase center of the pathogen pathway (8). In the best case, they should match.

Thus, it can be seen that the edge (12) together with the parabolic cylinder (7) transforms the PV waves in the same way as a parabolic mirror located in free space converts plane waves. The only difference is that simultaneously with the reflection of the PV waves, they are transmitted from the lower PV to the upper. It is known [1] that a parabolic mirror converts a diverging source wave into a plane wave. In the case under consideration, a cylindrical wave in the lower MF created by the pathogen (8) is converted into a plane wave of the upper MF, which runs towards the emitter (3) (see Fig. 1), that is, along the 0y axis.

The phase of the field in the direction perpendicular to the direction of propagation, that is, along the 0x axis, is constant. The amplitude distribution U (x) along this axis is known [1]

From relation (2) it can be seen that at the edges of the parabolic cylinder (7) with m = x _m = 2F, the amplitude distribution vanishes, since at these points the vanishing coefficient of the displacement (1) vanishes.

The wave in the upper MF enters the emitter (3), which is made in the form of two rectangular plates (10) and (11), which are connected to the middle plate (5) and the upper plate (6). Thus, the rectangular plates form a flat horn connected to the upper MF and excited by a wave formed in this MF. The line of intersection of the rectangular plates (10) and (11) should be between the upper plate (5) and the middle plate (6) so that the horn expands with distance from the airfoil.

The wave of PV is converted into a wave of a flat horn. In this case, the AFR along the 0x axis remains unchanged. Only the AFR of the field V (z) varies along the 0z axis. It coincides with the distribution of the horn wave field. 7 shows the emitter (3) with a symmetrical arrangement of a rectangular plate (9) and a rectangular plate (10). For him, the AFR of the field V (z) in the output plane С-С ′ of the flat horn, which is located at a distance Z from the line of intersection of the rectangular plates (10) and (11), has the following form:

where 2z _{m is the} size of the output section of the flat speaker. From relation (3) it can be seen that the phase distribution is described by a quadratic law typical of horn waves. The amplitude distribution is close to uniform under the condition z _m << L, which is usually satisfied.

From relations (2) and (3) it can be seen that AFR in the vertical and horizontal planes are formed independently of each other. In the horizontal plane, it is created by a planar mirror (2) and an irradiator (1), and in the vertical plane, by an emitter (3). This method of forming AFR allows you to create a fan pattern with an arbitrary ratio of the width of the main beam in different planes. The ratio of the width of the main beam in the horizontal plane (plane of the vector H) Δθ _h to the width of the beam in the vertical plane Δθ _ν (plane of the vector E) is approximately determined by the ratio of the dimensions of the output plane of the emitter (3)

All elements of the horn-antenna, forming the phase distribution most critical to frequency changes, are frequency-independent devices. Therefore, the direction of the main beam of its beam is constant and does not change with frequency. It is always oriented along the 0y axis. Due to this, an extension of the working range of the horn-antenna is achieved.

Horn Mirror Horn D_a in the horizontal plane depends on the distance between the pathogen (8) and the wall (7) d. On Fig shows the calculated daylight in the horizontal plane. The curve is obtained at F = 500, x_m= 1000, d = 10. All dimensions are given in millimeters. The frequency is 1.3 GHz. It can be seen that the UBL reaches an acceptable value for many practical problems of -25 dB. Thus, a reduction in the SLL of the horn antenna is achieved.

A fragment of the first additional embodiment of the mirror-horn antenna is shown in Fig.9. In it, the pathogen (8) is made in the form of a pin (14) made of metal and installed between the lower plate (4) and the middle plate (5) perpendicular to it without galvanic contact with the indicated plates and the segment (16) of the transmission line, in the gap between the middle plate (5) and the pin (14) include a concentrated capacitor (15), the segment (16) of the transmission line has an inner end connected by a central conductor to the pin (14) through an opening in the lower plate (4), and an external end forming an outlet antennas, the screen of the segment of the transmission line has galv contact with the bottom plate (4).

In this further embodiment of the horn antenna, an improvement in its matching is achieved. The pin (14) has a reactive inductive reactance, which is connected in series with the active resistance. The ideal matching of such a load with the segment (16) of the transmission line is impossible due to the presence of the reactive component of the input impedance. To compensate, a concentrated capacitor (15) is included in the gap between the pin (14) and the middle plate (5). It can be made in the form of a mounted circuit element or in the form of a metal board, which together with the middle plate (5) forms a flat capacitor. Depending on the frequency range and geometric dimensions of the pin (14), the need for additional capacitive elements can be eliminated, since an acceptable capacitance will arise between the flat top of the pin (14) and the middle plate (5).

A fragment of a second additional embodiment of a horn antenna is shown in FIG. 10. In it, the irradiator (1) is made with one exciter (8) in the form of two tapes (17) and (18) made of metal and a segment of the transmission line (16), tapes (17) and (18) have galvanic contact with each other, their the axes are located at right angles to each other, and the axis of one tape (17) is parallel to the wall (9) and perpendicular to the bottom plate (4) and the middle plate (5) and connected to the middle plate (5) through a capacitor (15), and the axis of the other tape (18) is perpendicular to the wall (9) and does not have galvanic contact with it, the segment (16) of the transmission line has an inner end, is connected a central conductor with a tape (18), the axis of which is perpendicular to the wall (9), through the hole in the specified wall, and the external end, which forms the antenna output, and the screen of the segment (16) of the transmission line has galvanic contact with the wall (9).

The advantage of this embodiment of the mirror-horn antenna is the convenience of mounting the pathogen, due to the orientation of the axis of the segment (16) of the transmission line parallel to the antenna plane. Most often, the segment (16) of the transmission line is made in the form of a coaxial connector, which is installed on the outer surface of the mirror-horn antenna. In this case, the antenna is connected to external devices using a coaxial cable, which has a threaded connection with the specified connector. Attaching a coaxial cable to a connector mounted on a wall (9) is in many cases more convenient than connecting to a connector mounted on a bottom plate (4).

For example, when creating antennas with a total-differential beam pattern, it is necessary to use two mirror-horn antennas located parallel to each other. When the connector is installed on the bottom plate (4), the outputs of two mirror-horn antennas are opposite each other at a small distance, as shown in Fig. 11a. Attaching cables or other devices to them is difficult, and often impossible at all, due to lack of space. When installing the connector on the wall (9) (see Fig. 11b), their connection with external devices is facilitated.

The third additional embodiment of the mirror-horn antenna without emitter (3) is shown in Fig. 12. In it, in order to expand the functionality, the irradiator (1) is made with two pathogens (19) and (20), and these pathogens (19) and (20) are located symmetrically with respect to the plane of symmetry (21) of the guide of the parabolic cylinder (7), and the external the ends of the transmission lines of the pathogens (19) and (20) form two outputs (22), (23) of the antenna.

The expansion of the functionality of the mirror-horn antenna according to the third additional option is associated with an increase in the number of its inputs, which allows, by connecting the specified inputs (22), (23) with external circuits, to change the antenna pattern in a predetermined manner.

A fourth additional embodiment of the horn antenna is shown in FIG. 13. In it, in the third additional version of the mirror-horn antenna, a common-mode power divider (24) is introduced into two equal parts, the lateral shoulders of which are connected to the outer ends of the transmission line segments of the pathogens (19) and (20), which form the outputs (22) and (23 ) In the fourth additional embodiment, the implementation of the mirror-horn antenna is achieved by reducing the UBL antenna bottom in the plane of the vector H or in the horizontal plane.

In the considered embodiment of the mirror-horn antenna, the irradiator (1) is formed by two pathogens (19) and (20). When a signal is applied to the central input (25) of the in-phase power divider (24), signals having the same phase and same amplitude appear at its side outputs connected to inputs (22) and (23). Therefore, pathogens (19) and (20) excite the lower PV in phase. The resulting MD of the radiation field in the lower MF can be written as follows:

where 2a is the distance between pathogens (19) and (20), and d is the distance from the tape (17) to the wall (9) when executing pathogens (19) and (20) in accordance with the second additional variant of the mirror-horn antenna (see Fig. 10).

The expression U (x) describing the amplitude distribution of the field along the 0x axis differs from relation (2) only in that the function D (θ) is now given by formula (5). On Fig shows the calculated MD of the horn antenna in the plane of the vector H. Curves 26-28 are obtained for F = 500, x _m = 1000, d = 30, a = 25, 30, 35, f = 1.3 GHz. It can be seen that the use of two pathogens (19), (20) and a common-mode power divider (24) allows one to significantly reduce the SLL of the MD-horn antenna compared to the case when the feed (1) contains one pathogen (8) (see Fig. 8). UBL decreases by almost 10 dB.

A fifth additional embodiment of the horn antenna is shown in FIG. In order to form a total-difference radiation pattern in the plane of the electric field vector, a hybrid connection (32), an additional irradiator (29), an additional planar mirror (30) and an additional one are introduced into the mirror-horn antenna made in accordance with the second additional option emitter (31), identical to the planar mirror (2), irradiator (1) and emitter (3) and located symmetrically with respect to the plane of symmetry (35), which is parallel to the metal plates of the planar mirror (2), sum-and-difference output (33) and (34), a hybrid junction (32) connected to the outputs (1) and (31) feed elements, and the free inputs (36) and (37) a hybrid compound (32) form inputs mirror-horn antenna.

When a signal is applied to the free inputs (36) and (37) of the hybrid compound (32), signals of the same amplitude but with different phase ratios appear at its total-difference outputs (33), (34). Suppose that when a signal is applied to a free input (36), in-phase outputs (33), (34) are formed in-phase signals, and when a signal is fed to a free input (37), total-difference outputs (33), (34) are formed signals. Then, when the mirror-horn antenna is excited from the side of the free input (36), the emitter (3) and the additional emitter (31) form in the free space the radiation field with a beam, respectively, F _{1, 2} . The indicated MDs are identical in the horizontal plane, and in the vertical plane they differ only by factors

where b is the distance between the emitter (3) and the additional emitter (31), F ₀ (θ) is the DN of the solitary emitter (3). The total daylight of the entire horn antenna F _s (θ) is equal to the sum of daylight F _{1, 2}

Similarly, when a signal is applied to the free input (37), the emitter (3) and the additional emitter (31) form in the free space radiation fields with DNs F _{1, 2} that are different from the DNs (6) by the signs:

In this mode, the total MD of the horn antenna F _d (θ) is written as follows:

The DN F _s (θ) is called the total, and F _d (θ) - the differential DN of the horn antenna.

In Fig. 16, curves (38) and (39) show typical total and differential MDs of a horn-mirror antenna made in a fifth additional embodiment. The difference DN has zero in the direction θ = 0. In the same direction, it has the maximum steepness, which is effectively used to increase the accuracy of direction finding in radar systems.

A sixth additional embodiment of the horn antenna is shown in FIG. In it, in order to reduce the SLL in the plane of the electric field vector into the main emitter (1) and the additional emitter (31) of the mirror-horn antenna, made in the fifth embodiment, it is symmetrical about the plane of symmetry (35) parallel to the metal plates of the planar mirror (2), the first additional rectangular plate (40) and the second additional rectangular metal plate (41) are respectively introduced; two edges of the first additional rectangular plate (40) are parallel to the rectilinear edges the middle plate (5) and the upper plate (6), one of these edges being located between the middle plate (5) and the upper plate (6), and the other edge is located in the plane passing through the edges of the rectangular plates (10) and (11) having no connection with the middle plate (5) and the upper plate (6).

The horn-mirror antenna according to the sixth additional embodiment operates as follows. When a signal is applied to the free input (36) of the hybrid compound (32), the irradiator (1) and the additional irradiator (29) are excited in phase. Due to this, in-phase waves appear in the planar mirror (2) and the additional planar mirror (30), exciting the emitter (3) and the additional emitter (31). As a result, the mirror-horn antenna forms a total DN in the vertical plane.

In the fifth horn mirror antenna, according to the fifth additional embodiment, the field distribution in the output plane of the emitter (3) and the additional emitter (31) coincides with the horn wave field in the plane of the vector E. This field has an amplitude distribution close to uniform. This amplitude distribution corresponds to UBL, which for a beam with a width less than 30 ° reaches a level of -13 dB. Such a UBL is unacceptable for many radar applications.

In the mirror-horn antenna according to the sixth additional embodiment, the SLL is reduced by the first additional rectangular plate (40) and the second additional rectangular plate (41). Due to the symmetry of the horn antenna relative to the plane (35), it suffices to consider the amplitude distribution of the field in the output plane of the emitter (3), which changes with the help of the first additional rectangular plate (40).

In the mirror-horn antenna according to the sixth additional embodiment, the emitter (3) is a double flat horn. One of the horns is formed by a rectangular plate (10) and the first additional rectangular plate (40), and the other horn is formed by the first additional rectangular plate (40) and a rectangular plate (11). In each of the flat horns, the amplitude distribution is uniform, but the field intensity is different. It depends on the distances h _{1, 2} from the edge of the first additional rectangular plate (40) located between the middle plate (5) and the upper plate (6), to the middle plate (5) and the upper plate (6), as well as on the distances b _{1, 2} from the other edge of the first additional rectangular plate (40) parallel to the specified edge of the first additional rectangular plate (40) to the edges of the rectangular plates (10) and (11) that are not connected to the middle plate (5) and the upper plate (6 )

When the emitter (3) is excited by a planar mirror (2), the power is divided between the first and second flat horns with dimensions h ₁ , b ₁ and h ₂ , b _2, respectively, with respect to h ₁ / h ₂

where P _{1, 2} - power received in the first and second speaker. In the output plane of the emitter (3) power P _{1, 2 are} approximately expressed in terms of electric field strengths E _{1, 2} as follows:

where W ₀ = 120π - wave impedance of free space.

From relations (10) and (11) we obtain the ratio of the field strengths in the output plane

From the expression (12) it can be seen that choosing, for example, b ₁ = b ₂ and h ₂ > h ₁ ,

it is possible to concentrate the field in the second flat horn (E ₂ > E ₁ ). In this case, in the output plane of the emitter (3) and the additional emitter (31), an amplitude field distribution is formed that decreases to the edges. It is known [1] that such an amplitude distribution corresponds to MDs with reduced SLL.

On Fig shows the calculated MD obtained for the frequency f = 1.3 GHz and b ₁ = b ₂ = 50 mm, the length of the flat speaker is 200 mm. Curves (42) - (44) correspond to the ratio E ₁ / E ₁ = 1, 0.7, 0.5. From Fig. 18 it is seen that a decrease in the ratio of the field amplitudes in the output plane of the irradiator (3) and the additional irradiator (31) can significantly reduce the level of the first side lobe and bring it to a value of -30 dB, which is acceptable for most radar applications.

A fragment of a seventh additional embodiment of a mirror-horn antenna is shown in Fig. 19. In order to form a sum-difference directional pattern in the plane of the magnetic field vector, a hybrid connection (32) is introduced in the mirror-horn antenna made in the third additional embodiment, the total-difference outputs (33), (34) of which are connected to the external ends segments of transmission lines of pathogens (19), (20). The free outputs (36) and (37) of the hybrid connection (32) form the outputs of the mirror-horn antenna.

The horn-mirror antenna according to the seventh embodiment operates as follows. Let the signal go to the free input (36) of the hybrid connection (32). In this case, in-phase outputs (33) and (34) form in-phase signals that are transmitted to pathogens (19) and (20). When a signal is applied to a free input (37), antiphase signals are generated at the total difference outputs (33) and (34), which also enter the exciters (19) and (20). Since the mirror-horn antenna is a linear device, its excitation can be considered separately by the pathogen (19), and then the pathogen (20). The total field created by both pathogens (19), (20) will be the sum of the fields generated by each of them.

Consider the excitation of a mirror-horn antenna by a pathogen (19), which is located at x> 0 (see Fig. 4). The analysis of the excitation of a horn antenna in this case differs from that presented above when describing a horn antenna in the main version only in that the pathogen (19) is displaced relative to the plane of symmetry (21) of the parabolic cylinder (7) a distance a . If this shift is small compared with the focal length F, then the amplitude distribution at the output of the planar mirror (2) is still described by function (2). The phase distribution Φ (x) can be approximately represented as follows:

The AFR along the x coordinate given by formulas (2) and (14) remains unchanged up to the output plane of the emitter (3). The appearance of a linearly changing phase leads to the rotation of the MD of the horn antenna in the horizontal plane by an angle α.

Similarly, when a specular-horn antenna is excited by a pathogen (20) that is displaced relative to the plane of symmetry by a distance of -a, the radiation field has a horizontal direction of the radiation pattern that is rotated by an angle of α.

Now we can write the ratio for the total and difference MDs, which are created when the mirror-horn antenna is excited simultaneously by pathogens (19) and (20), to which in-phase and antiphase signals are applied

,

,

where, as before, F _s (θ) is the total, F _d (θ) is the differential MD, and F ₀ (θ) is the MD when the pathogen is placed in the plane of symmetry (21). It is seen from formulas (15) that the difference pattern has zero at θ = 0, and the total pattern reaches its maximum at this point.

Thus, we have shown that when a specular horn antenna is excited from the free input side (36), the total beam pattern is formed in free space, and when it is excited from the free input side (37), a differential beam pattern is formed.

On Fig presents a horn-antenna made in the eighth additional option. In it, an additional planar mirror (30), an additional irradiator (29) and an additional emitter (31) identical to the planar mirror (12) are introduced into the mirror-horn antenna according to the third embodiment in order to form a total-difference radiation pattern simultaneously in the planes of the electric and magnetic field vectors 2), the irradiator (1) and the emitter (3), and located symmetrically with respect to the plane of symmetry (35), which is parallel to the metal plates of the planar mirror (2), is also introduced into the directional antenna for a diagram-forming circuit (45), which has four total-differential outputs (46) - (49) and at least three inputs (50) - (53), the total-differential outputs (46) - (49) are connected to the outer ends of the line segments transmission of pathogens of the irradiator (1) and the additional irradiator (31).

The beam-forming circuit (45) belongs to the class of beam-forming circuits of monopulse antennas and operates according to the algorithm described by its scattering matrix S

,

,

.

,

,

.

Index i corresponds to waves incident on free outputs (50) - (53), and index r corresponds to waves running from total difference outputs (46) - (49), i.e., waves reflected from them, in accordance with the terminology, adopted in the microwave technology. Each column of the scattering matrix S describes signals at the sum-difference outputs (46) - (49) when one of the free outputs (50) - (53) is excited by a signal of unit amplitude.

From the relationships (16) it can be seen that when a signal is supplied to the free output (46), all signals supplied to the exciters of the irradiator (1) and the additional irradiator (31) are in phase. In this case, as was shown above in the analysis of the functioning of horn antennas made according to the fifth and seventh additional options, the emitter (3) and the additional emitter (31) create radiation in space that has a total beam both in horizontal and in vertical planes.

When a signal is supplied to a free input (47) in accordance with formulas (16), both inputs of the irradiator (1) and the additional irradiator (31) are excited in phase, but there is a difference between the signals at the inputs of the irradiator (1) and the additional irradiator (31) phases equal to 180 °. In this case, the mirror-horn antenna forms in the free space the beam, which in the horizontal plane is total, and in the vertical plane it is differential.

When a signal is applied to a free input (48) in accordance with formulas (16), the inputs of the irradiator (1) and the additional irradiator (31) are excited in phase, but there is no difference between the signals at the inputs of the irradiator (1) and the additional irradiator (31) phases. In this case, the mirror-horn antenna forms in the free space of the beam, which in the horizontal plane is difference, and in the vertical plane total.

Finally, when applying a signal to a free input (49) in accordance with formulas (16), both inputs of the irradiator (1) and the additional irradiator (31) are excited out of phase, and between the signals at the inputs of the irradiator (1) and the additional irradiator (31) there is a phase difference of 180 °. In this case, the mirror-horn antenna forms in the free space of the beam, which in the horizontal and vertical planes is differential.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed invention:

- an antenna device embodying the claimed invention is intended for use in industry, namely, in the technique of antennas, for example as a transceiver antenna of a radar;

- for the claimed device in the form described in the independent clause of the claims, the possibility of its implementation using the means described in the application is confirmed;

- the antenna device embodying the claimed invention allows to realize the following technical result: to obtain MDs with low UBL in two main planes, to create a main beam of MDs with a large ratio of the widths in two main planes, to create MDs of the total-difference type in two main planes.

Information Sources Used

1. Sazonov D.M. Antennas and microwave devices. M .: Higher school. 1988.

2. S.E. Banks. Design and experimental study of the array of slot emitters. // Radio engineering and electronics, 2004, t. 49, No. 6, p. 701-706.

Claims (10)

1. Mirror-horn antenna containing a planar mirror, irradiator and emitter, moreover, the planar mirror is made in the form of upper, lower and middle plates, which are made of metal and mounted parallel to each other, and a parabolic cylinder, which is made of metal and installed between the bottom and the upper plates and has galvanic contact with them, and its axis is perpendicular to the planes of these plates, the middle plate is installed between the upper and lower plates and has an edge located between the parabolic the cylinder and its focus, and the gap between the edge and the parabolic cylinder has a constant width, the irradiator is installed between the lower and middle plates, characterized in that the irradiator is made in the form of at least one pathogen and a wall made of metal and installed between the lower and the middle plates perpendicular to them, the wall is also installed perpendicular to the plane of symmetry of the guide of the parabolic cylinder, the upper and middle plates are made with straight edges perpendicular to the plane In order to achieve symmetry of the guide of the parabolic cylinder and located at a distance from the top of the guide of the parabolic cylinder exceeding its focal length, the emitter is made in the form of two rectangular plates made of metal, the edges of which are connected with the straight edges of the upper and middle plates, and the planes of rectangular plates have an intersection line located between the upper and middle plates. 2. Mirror-horn antenna according to claim 1, characterized in that a concentrated capacitor is included in the gap between the middle plate and the pathogen, the transmission line segment has an inner end connected by a central conductor to a pin through an opening in the lower plate, and an outer end forming an exit antennas, the screen of the segment of the transmission line has galvanic contact with the bottom plate. 3. Mirror-horn antenna according to claim 1, characterized in that the irradiator is made with one exciter in the form of two tapes and a segment of the transmission line, the tapes are made of metal and have galvanic contact with each other, their axes are located at right angles to each other moreover, the axis of one tape is parallel to the wall and perpendicular to the plates and connected to the upper plate through a capacitor, and the axis of the other tape is perpendicular to the wall and does not have galvanic contact with it, a segment of the transmission line has an inner end connected to ntralnym conductor ribbon whose axis is perpendicular to the wall through an opening in said wall, and an outer end forming the output of the antenna and the screen of the transmission line segment has a galvanic contact with the wall. 4. The mirror-horn antenna according to claim 1, characterized in that the irradiator is made with two pathogens, moreover, these pathogens are located symmetrically relative to the plane of symmetry of the parabolic cylinder guide, and the outer ends of the transmission lines of the pathogens form two antenna outputs. 5. Mirror-horn antenna according to claim 1 or 4, characterized in that an in-phase power divider is introduced into the irradiator into two equal parts, the lateral shoulders of which are connected to the outer ends of the segments of the transmission lines of the pathogens. 6. Mirror-horn antenna according to claim 1 or 3, characterized in that a hybrid connection and an additional planar mirror, an additional irradiator and an additional radiator are identical to the planar mirror, irradiator and radiator and are located symmetrically with respect to the plane of symmetry, which is parallel the planar mirror plates, and the total-differential outputs of the hybrid connection are connected to the central inputs of the common-mode power dividers into two equal parts of the main and additional light irradiators. 7. The horn-mirror antenna according to claim 1, characterized in that the first and second additional rectangular plates are respectively introduced into the main and additional radiators symmetrically with respect to the plane of symmetry parallel to the planar mirror plates, the two edges of the first additional rectangular plate are parallel to the straight edges of the middle and the upper plates, one of these edges being located between the middle and upper plates, and the other edge is located in a plane passing through the edge and rectangular plates which do not have connections with the middle and upper plates. 8. The horn-mirror antenna according to claim 6, characterized in that the first and second additional rectangular plates are respectively introduced into the main and additional radiators symmetrically with respect to the plane of symmetry parallel to the planar mirror plates, the two edges of the first additional rectangular plate are parallel to the straight edges of the middle and the upper plates, one of these edges being located between the middle and upper plates, and the other edge is located in a plane passing through the edge and rectangular plates which do not have connections with the middle and upper plates. 9. Mirror-horn antenna according to claim 1 or 4, characterized in that a hybrid connection is introduced into it, the total-differential outputs of which are connected to the external ends of the segments of the transmission lines of pathogens. 10. The horn-mirror antenna according to claim 1 or 4, characterized in that an additional planar mirror, an additional irradiator and an additional emitter identical to the planar mirror, irradiator and emitter and located symmetrically with respect to the plane of symmetry that is parallel to the planar mirror plates are inserted into the directional antenna , a diagram-forming circuit has also been introduced into the omnidirectional antenna, which has four total-differential outputs and at least three inputs, the total-differential outputs are connected to the outer ends of the transmission lines of the pathogens of the irradiator and the additional irradiator.

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