JPH07336135A - Antenna device - Google Patents

Abstract

PURPOSE:To provide an antenna device capable of tracking an object with stable high sensitivity over a wide range. CONSTITUTION:This device is provided with a beam formation control circuit 9 to be connected to a digital beam formation circuit 5. The digital beam formation circuit 5 is controlled so as to make two beams used for a monopulse processing be different for a fixed angle over the entire directions by the beam formation control circuit 19. By providing the beam formation control circuit 9, the object is tracked with the stable high sensitivity over the wide range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conformal array antenna composed of a plurality of element antennas mounted on a predetermined position on the surface of an aircraft or a ship.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional antenna of this type. In FIG. 8, reference numeral 1 denotes a conformal array antenna having a plurality of antenna elements provided on a hemisphere, and 2 denotes the conformal antenna 1. Hemispherical structural substrate,
3 ₁ to 3 _n is the n mounted along said structure antenna elements, 4 ₁ to 4 _n is the antenna element 3 ₁ to 3
_n signal lines 5 connected to n are the signal lines 4 ₁ to 4 _n
, 6 _{1 to} 6 _m are m output terminals of the digital beam forming circuit 5, 7 is a monopulse pattern forming circuit connected to the output terminals 6 _{1 to} 6 _m , 8 ₁ to 8 _k are k output terminals of the monopulse pattern forming circuit 7. FIG. 9 is a configuration diagram of the antenna elements 3 _{1 to} 3 _n forming the conformal array antenna 1, showing the antenna element 3 ₁ as an example, 14 ₁ is an element antenna, 15 ₁ is a low noise amplifier, 16 ₁ is an analog-digital converter.

Next, the operation will be described. The microwave signals received by the element antennas 9 _{1 to} 9 _n of the antenna elements 3 _{1 to} 3 _n attached to the structural substrate 2 of the conformal array antenna 1 are amplified by the low noise amplifiers 15 ₁ to 15 _n . The microwave signals amplified by the low noise amplifiers 15 ₁ to 15 _n are directly or IF (Intermediary).
ate Frequency), and its output is converted by the analog-digital converters 16 _{1 to} 16 _n into a digital signal containing phase and amplitude information. The digital signals are discrete Fourier transform in digital beam forming circuit 5 is transmitted through the signal line 4 ₁ to 4 _n, fast Fourier transform,
Beam combining is performed as a digital signal using a technique such as Winograd Fourier transform. The digital signals corresponding to the m beams are calculated via the output terminals 6 _{1 to} 6 _m in the monopulse pattern forming circuit 7 to calculate the sum and difference of each of the two signals to form a monopulse pattern. pattern output terminal 8 ₁ ~8 _k
Is output from.

[0004]

Since the conventional antenna device is constructed as described above, the beam of the antenna can be arbitrarily constructed over the half space. However, when selecting two beams, the beam crossing Since the amount, that is, the level of the intersection with respect to the peak level of the beam is not constant, it is impossible to stably obtain the maximum sensitivity.

The present invention has been made in order to solve the above problems, and obtains an antenna device which can stably obtain the maximum sensitivity and can track a target with high sensitivity over a wide angle. With the goal.

[0006]

In the antenna devices according to the first to fourth embodiments of the present invention, when the digital signals are combined by the digital beam forming circuit 5, the amount of intersection of any two beams is determined. It is provided with a circuit for controlling it to be constant.

[0007]

In the present invention, as described in the radar technology (edited by Takashi Yoshida, published by The Institute of Electronics, Information and Communication Engineers), the beam forming control circuit is designed so that the amount of beam crossing is 1.1 db in order to obtain the maximum sensitivity. Control can be performed and a monopulse pattern can be synthesized by using an arbitrary pattern between two beams synthesized by the digital beam forming circuit, so that maximum sensitivity can be stably obtained, and all elements can be effectively used over a wide space. This enables the formation of a monopulse pattern that can be used for highly sensitive target tracking of radar.

[0008]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to FIG. Conformal array antenna 1 is provided with a plurality of elements on the hemisphere in FIG. 1, 2 structural substrate hemispheres constituting the conformal antenna 1, 3 ₁ to 3
_n is an n number of antenna elements attached along the structure, 4 ₁ to 4 _n is an n number of signal lines connected to the antenna elements 3 _{1 to} 3 _n , and 5 is the above signal lines 4 ₁ to 4 _n Connected to the digital beam forming circuit, 6 _{1 to} 6 _m are m output terminals of the digital beam forming circuit 5, 9 is a beam forming control circuit connected to the digital beam forming circuit 5, and _{1 1} to 10 _j are the above. The j control signal lines of the beam forming control circuit 9, 7 are monopulse pattern forming circuits connected to the output terminals 6 _{1 to} 6 _m , and 8 ₁ to 8 _k are k output terminals of the monopulse pattern forming circuit 7. is there.

Next, the operation will be described. The digital signals output from the antenna elements 3 _{1 to} 3 _n attached to the structural substrate 2 of the conformal array antenna 1 are transmitted through the signal lines 4 ₁ to 4 _{n and} are subjected to individual Fourier transform and fast Fourier transform in the digital beam forming circuit 5. Conversion, Winog
Beam combining is performed as a digital signal using a technique such as rad Fourier transform. At this time, that is, when beam combining is performed, control is performed via the control signal lines 10 ₁ to 10 _j so that the amount of intersection of any two beams becomes 1.1 db in the beam forming control circuit 9. Synthesized m
The digital signals corresponding to the beam of the book are output terminals 6 ₁ ...
The sum and difference of the respective signals are calculated in the monopulse pattern output circuit 7 via 6 _m to form a monopulse pattern, which is output from the monopulse pattern output terminals 8 ₁ to 8 _k . Therefore, the maximum sensitivity can be stably obtained, and all the elements can be effectively used over a wide space to enable highly sensitive target tracking of the radar.

Embodiment 2. Next, a second embodiment of the present invention will be shown. FIG. 2 shows Example 2 and 1 to 10 _j are the same as those shown in FIG. Reference numeral 11 denotes a biaxial beam forming control circuit connected to the digital beam forming circuit 5.

In addition to the effects shown in the first embodiment, the antenna device constructed as described above has an amount of intersection of two arbitrary beams of 1.1 db in the directions of two orthogonal axes.
Since it is possible to select the beam so as to become, it becomes possible to more effectively use all the elements and perform highly sensitive three-dimensional target tracking of the radar.

Embodiment 3. Next, a third embodiment of the present invention will be shown. FIG. 3 shows Example 3 and 1 to 10 _j are the same as those shown in FIG. Reference numeral 12 is a beam selection correction circuit connected to the beam forming circuit 9, and 13 _{1 to} 13 _l are one beam control signal line connected to the beam selection correction circuit 12. Next, the operation will be described. 4 and 5 are schematic diagrams of a conformal antenna and an antenna beam. In the antenna devices of the first and second embodiments, no matter which direction the antenna beam is directed, the amount of intersection of the two beams is 1.1 db as shown in FIG. The two beams were selected so as to be α. In the antenna device of this embodiment, the following correction is additionally performed. Assuming that the desired angle is θ from the front direction as shown in FIG. 5, the beam width θb is 1 / where the projection aperture length from the front direction of the antenna is L ₀ and the projection aperture length from the θ direction is L.
It changes in proportion to (L / L0).

Therefore, when the beams are directed in the θ direction, the beam control signal line 1 is controlled by the beam selection correction circuit 12 so that the difference β in the directivity angles of the two beams becomes equal to the expression 1.
Beam selection is performed through 3 _{1 to} 13 _l .

[0014]

[Equation 1]

In the antenna device configured as described above, not only the effect shown in the first embodiment but also the beam is selected by correcting so that the amount of intersection of the two beams in an arbitrary direction is optimized. This makes it possible to use all the elements more effectively to achieve highly sensitive target tracking of the radar.

Example 4. A fourth embodiment of the present invention will be described. FIG. 6 shows a fourth embodiment. 1 to 11 are the same as those shown in FIG. 2, and 12 to 13 _l are the same as those shown in FIG.

In addition to the effect shown in the third embodiment, the antenna device constructed as described above is corrected so that the amount of intersection of two arbitrary beams in the directions of two orthogonal axes is optimized. Since it is possible to select the beam, it is possible to more effectively use all the elements and perform highly sensitive three-dimensional target tracking of the radar.

Although the hemisphere is used as the conformal array antenna 1 in the above-mentioned embodiment, the invention is not limited to this. It may be a shape having a part of a cylinder, a spherical cone, or the like, or a part of a curved surface having a composite shape of these, or a plurality of locations. The polarized wave is not limited to the linear polarized wave, and a circular polarized wave can be used.

[0019]

As described above, according to the present invention, the following effects can be expected.

That is, according to the first embodiment, when the digital signals from the conformal array antenna 1 are combined by the digital beam forming circuit 5, the beam forming control circuit 9 optimizes two arbitrary beams. Since the control is performed and the sum signal and the difference signal are calculated by the monopulse pattern forming circuit 7, it is said that the maximum sensitivity cannot be stably obtained because the amount of beam crossing which the conventional antenna has is not constant. Issues are improved.

According to the second embodiment, when the digital signals from the conformal array antenna 1 are combined in the digital beam forming circuit 5, the biaxial beam forming control is performed so that any two arbitrary beams are optimized. Since the circuit 11 controls and the monopulse pattern forming circuit 7 calculates a sum signal and a difference signal, the maximum sensitivity can be stably obtained because the amount of beam crossing that a conventional antenna has is not constant. The problem of being unable to do so is improved.

Further, according to the third embodiment, when the monopulse beam is directed in the direction of the angle θ, when the digital signal from the conformal array antenna 1 is synthesized by the digital beam forming circuit 5, the beam selection correction circuit 12 arbitrarily determines. Make corrections so that the two beams of
Furthermore, since the beam forming control circuit 9 performs beam forming control and the monopulse pattern forming circuit 7 calculates the sum signal and the difference signal, the amount of beam crossing that a conventional antenna has is not constant. The problem that stable maximum sensitivity cannot be obtained is improved.

Further, according to the fourth embodiment, when the monopulse beam is directed in the angle θ direction, when the digital signal from the conformal array antenna 1 is synthesized by the digital beam forming circuit 5, the beam selection correction circuit 12 arbitrarily determines. Make corrections so that the two beams of
Furthermore, since the beam forming control is performed by the biaxial beam forming control circuit 11 and the sum signal and the difference signal are calculated by the monopulse pattern forming circuit 7, the amount of beam crossing that the conventional antenna has is constant. Therefore, the problem that the maximum sensitivity cannot be stably obtained because of not being satisfied is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an antenna device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing an antenna device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing an antenna device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram of a conformal antenna and an antenna beam when a monopulse beam is directed in a 0 ° direction.

FIG. 5 is a schematic diagram of a conformal antenna and an antenna beam when a monopulse beam is directed in the θ direction.

FIG. 6 is a configuration diagram showing an antenna device according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional antenna device.

FIG. 8 is a configuration diagram of an antenna element of a conventional antenna device.

[Explanation of symbols]

 1 Conformal Antenna 2 Structural Base 3 Antenna Element 4 Signal Line 5 Digital Beam Forming Circuit 6 Output Terminal 7 Monopulse Pattern Forming Circuit 8 Monopulse Pattern Output Terminal 9 Beam Forming Control Circuit 10 Beam Data Output Terminal 11 Two-axis Directional Beam Forming Control Circuit 12 beam selection correction circuit 13 beam control signal line 14 element antenna 15 low noise amplifier 16 analog-digital converter

Claims (8)

[Claims] 1. A conformal array antenna comprising a plurality of element antennas mounted at a predetermined position on the surface of an aircraft or a ship, and a digital beam forming circuit for combining outputs from the element antennas to form a plurality of beams. An antenna device comprising a monopulse forming circuit using any two beams synthesized by the digital beam forming circuit, and a beam forming control circuit for controlling the formation of the plurality of beams. 2. The beam forming control circuit sets an angular difference α such that the level of the intersection of the two beams is lowered by 1.1 db from the peak level of the beam in the direction in which the reception gain is maximized. The antenna device according to claim 1, wherein the antenna device is controlled so that the angular difference between the two beams is constant at α even when the monopulse beam is directed in an arbitrary direction. 3. A digital beam forming circuit for forming a plurality of beams by combining outputs from the element antennas in a conformal array antenna composed of a plurality of element antennas mounted at predetermined positions on the surface of an aircraft or a ship. A monopulse forming circuit using arbitrary two beams synthesized by the digital beam forming circuit, a beam forming control circuit for controlling formation of the plurality of beams, and the two beams depending on the direction of the monopulse beam. An antenna device comprising a beam selection correction circuit that corrects the angle difference between the two. 4. The beam selection / correction circuit uses the directivity angle difference between arbitrary two beams depending on the directivity direction of the monopulse beam as the α and the projection aperture length L ₀ from the direction in which the reception gain becomes maximum and the arbitrary angle. 4. The antenna device according to claim 3, wherein correction is performed so as to be α × (L ₀ / L) according to the projection aperture length L from the direction. 5. A conformal array antenna comprising a plurality of element antennas mounted at a predetermined position on the surface of an aircraft or a ship, and a digital beam forming circuit for combining outputs from the element antennas to form a plurality of beams. A monopulse forming circuit using arbitrary two beams synthesized by the digital beam forming circuit, and a biaxial beam for controlling not only the formation of the plurality of beams but also the orthogonal two axes. An antenna device comprising a formation control circuit. 6. The biaxial beam forming control circuit includes:
The level at the intersection of the two beams is 1.1d higher than the peak level of the beam in the direction that maximizes the reception gain.
6. An angle difference α that decreases by b is obtained in advance, and control is performed so that the angle difference between the two beams is constant at α even when the monopulse beam is directed in an arbitrary direction. The antenna device described. 7. A digital beam forming circuit for forming a plurality of beams by combining the outputs from the element antennas in a conformal array antenna composed of a plurality of element antennas mounted at predetermined positions on the surface of an aircraft or a ship. A monopulse forming circuit using arbitrary two beams synthesized by the digital beam forming circuit, and a biaxial beam for controlling not only the formation of the plurality of beams but also the orthogonal two axes. An antenna device comprising a formation control circuit and a beam selection correction circuit that corrects the angular difference between the two beams depending on the directivity direction of the monopulse beam. 8. The beam correction / selection circuit is configured so that a directivity angle difference between two arbitrary beams depending on a directivity direction of a monopulse beam is α, and a projection aperture length L ₀ from a direction in which a reception gain is maximum and an arbitrary value. 8. The antenna device according to claim 7, wherein the projection aperture length L from the angular direction is corrected to be α × (L ₀ / L).