JPH0430608A - Conformal array antenna - Google Patents

Abstract

PURPOSE:To improve the degree of freedom of the antenna design by taking a fixed point O onto a ground plate being a curved face, taking an orthogonal XY coordinate on a tangent plane at the fixed point O and arranging each element antenna on the surface of the ground plate being a cured face respectively at a point P at a distance (r) from the fixed point O on a geodestic line which is tangential to the plane in a direction theta with respect to the X axis while taking the fixed point as a start point. CONSTITUTION:At first, a fixed point O is taken onto a ground plate 1 being a cured face and an orthogonal XY coordinate is taken on a tangent plane 5 at the fixed point O. Then the fixed point O on the curved face ground plate 1 as a start point and a geodestic line 4 which is tangential to the direction tilted by an angle theta with respect to the X axis and to the direction tilted by an angle theta between a line O'P' and the X' axis shown in figure 2(a) is drawn from the start point. Then a point P at a distance (r) from the fixed point O on the geodestic line 4 is taken and the point is used as an arranged position of the element antenna 2. Similarly, the position P for all the element antennas 2 on the curved face ground plate is decided by repetitively mapping the position P' of each element antenna arranged at a prescribed period defined on the X'Y' plane onto the point of the curved face ground plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a conformal array antenna in which a plurality of element antennas are arranged on the surface of a curved ground plane.

[Conventional technology]

Conventionally, as a conformal array antenna.

J., 5aito, L., Haichele, T.
Numazaki, N., Orime.

T, Katagi,, 'Comparison o
f element arrangements of
a 5 pherical array', 1987
IEEE AP-3 International S
Symposium Digest, vol. 1. A
There is one shown in PO4-4. FIG. 5 is an element antenna arrangement diagram of the conformal array antenna shown above.

In the figure, (1) is a spherical ground plate, and (2) is an element antenna.

FIG. 5(a) shows element antennas arranged at equal intervals on latitude and longitude lines. In FIG. 5(b), the spherical surface is replaced with an equilateral triangular polyhedron, and element antennas are arranged at the vertices of the polyhedron. In FIG. 5(C), the spherical surface is replaced with an equilateral triangular polyhedron, and element antennas are arranged at the center of the polyhedron.

[Problem to be solved by the invention]

Conventional conformal array antennas have an arrangement of element antennas as shown above.

When attempting to arrange element antennas at a constant arrangement period on the surface of a ground plane whose shape is a curved surface that is not spherical, there is a problem that conventional arrangement configurations cannot be applied. The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to obtain a conformal array antenna with small arrangement period error of element antennas even on a ground plane having a curved surface other than 9-spherical surfaces.

[Means to solve the problem]

In order to achieve the above purpose, in a conformal array antenna in which multiple element antennas are arranged on the surface of a ground plane consisting of nine curved surfaces, each element is arranged at a constant periodicity defined in advance at orthogonal X'Y' coordinates on a plane. Antenna position P'
are expressed in polar coordinates (rθ), and orthogonal XY coordinates are determined on the tangential plane at fixed point 0 and fixed point O on the ground plane made of the above-mentioned curved surface.

When a geodesic line is defined that starts at fixed point 0 and touches the direction of θ from the It is something.

In addition, in a conformal array antenna in which a plurality of element antennas are arranged on the surface of a ground plate made of a curved surface symmetrical to the XZ plane, the ground plate made of the above curved surface and the XZ
When a plurality of points in a constant periodic arrangement are set on the line of intersection with the surface (central cross-sectional curve) and geodesics that are orthogonal to the XZ plane are defined using these points as starting points, the surface of the ground plate consisting of the above curved surface is Each element antenna is arranged on a constant periodic array of points on the geodesic line.

[Effect]

In a conformal array antenna in which a plurality of element antennas are arranged on the surface of a ground plane made of a curved surface configured as described above, the position of each element antenna in a constant periodic array defined in advance at orthogonal X'Y' coordinates on a plane. P' are each represented by polar coordinates (r, θ), and orthogonal XY coordinates are set on the ground plane made of the above curved surface at a fixed point O and on a tangent plane at the fixed point 0, and the geodesic coordinates are set from the fixed point 0 as the starting point and tangent in the direction of θ from the X axis. When the line is defined, each element antenna on the surface of the ground plane made of the above curved surface is located at a point P at a distance of r from the fixed point 0 on the above geodesic line.
By arranging them respectively, the geodetic coordinates of the element antenna arrangement position P' on the plane with the origin 0' as the pole match the geodetic coordinates of the element antenna arrangement position P' on the curved surface with the fixed point O as the pole. can be done.

In addition, in a conformal array antenna in which a plurality of element antennas are arranged on the surface of a ground plate made of a curved surface symmetrical to the XZ plane, the ground plate made of the above curved surface and the XZ
When a plurality of points in a constant periodic arrangement are set on the line of intersection with the surface (central cross-sectional curve) and geodesic lines perpendicular to the XZ plane are defined using these points as starting points, the surface of the ground plate made of the above curved surface is By arranging each element antenna on a point in a constant periodic arrangement on the geodesic line, the arrangement period of the element antenna on a plane and the arrangement period on the central cross-sectional curve and in the direction of the geodesic line orthogonal to the central cross-sectional curve can be adjusted. can be matched.

〔Example〕

Claim 1. and Claim 2 An embodiment of each will be described with reference to the drawings.

1st conjunction a - requirement 1. 1 is a schematic configuration diagram showing one embodiment of the present invention. (1) is a metal or dielectric ground plate consisting of a curved surface, (
2) is an element antenna arranged on the surface of the ground plate (1), and shows a case of a cross dipole type.

FIG. 3 is a diagram showing one position P' of an array of element antennas defined on a second plane. P' is the arrangement position of the element antenna (2), and (4) is a geodesic line connecting the origin O' and the arrangement position P' of the element antenna (2). Note that on the plane, the geodesic line (4) determined by the origin 0' and the placement position P' is this 2
It is a straight line connecting points.

It is a figure explaining how to decide the arrangement of the element antenna on the curved surface ground plate (1), (4) is the curved surface ground plate (1).
A geodesic line that is uniquely determined by giving the fixed point 0 above and the direction at the fixed point 0 [the direction that makes the angle θ with the X axis of the orthogonal XY coordinates defined on the tangential plane (5)], (5) is a curved ground plane (1) The tangential plane 9 point P at the fixed point 0 above is the element antenna (2) at a distance r on the geodesic line from the fixed point O, which is the starting point of the geodesic line (4).
placement position.

(6) is a tangential plane at the element antenna arrangement position P on the curved ground plane (1). X is the direction 10 rotations from the tangent direction of the geodesic line (4) at one point P on the tangent plane (6).
The orientation of the element antenna (2) with respect to the orthogonal X'Y' coordinate system is defined as the element antenna (2) shown in Figure 2.
The direction corresponds to the orthogonal x'y' coordinate system.

Figures 4(a) and 4(b) show examples of constant periodic arrays of element antennas defined on a plane; (a) is a square array;
(b) is a diagram of a triangular array. Each arrangement has an arrangement period in the X' force direction and in the Y' force direction DY.

Next, the method of determining the arrangement position of the element antennas on a curved surface and the position of one element antenna arranged at a constant period are shown. A method of setting the position P' of this element antenna (2) to the distance r from the origin 0' and the straight line 0'P' to the X' axis will be explained using the third red diagram.

First, orthogonal XY coordinates are determined on the fixed point O and the tangent plane (5) at the fixed point 0 on the two-curved ground plane (1). next.

Draw a geodesic line (4) that is tangent to the direction tilted by angle θ.

Furthermore, a point P at a distance r from the fixed point 0 is determined along this geodesic line (4), and this point is designated as the arrangement position of the element antenna (2).

Similarly, by repeating the mapping of the position P' of each element antenna in a constant periodic array defined on the x'y' plane to the point P on the curved ground plane, all the element antennas (2) on the nine curved ground planes are obtained. The position P of is determined.

In this way, the geodetic coordinates of the position P' of the element antenna defined on the plane with the origin O' as the pole.

Position P of the element antenna (2) on the curved surface with fixed point O as the pole
The geodetic coordinates of

This can be achieved by arranging the element antenna (2) so that the direction of the straight line 0'P' and the direction of the tangent of the geodesic line (4) at the point P of the element antenna (2) match. (1) is a metal or dielectric ground plate made of a curved surface that is symmetrical with respect to the XZ plane, and (2) is an element antenna arranged on the surface of the curved ground plate (1), which is a cross dipole type. . (3) is the central cross-sectional curve of the curved ground plate (1), and (4) is the geodesic curve.

Note that the central cross-sectional curve (3) is defined as the line of intersection between the XZ plane and the surface of the curved ground plate (1) that is symmetrical with respect to the XZ plane.

The geodesic line (4) has a center section curve (2411th)
3) Arrangement position of element antenna arranged at a constant period above (7)
A point and a virtual point (8) are determined, and these points are defined as a starting point and a line on a curved surface perpendicular to the XZ plane.

It is a figure which shows the arrangement position of the element antenna on the 24th ring center cross-sectional curve (3). (7) is the central cross-section curve (3
), (8) is a virtual point defined on the central cross-sectional curve.

Arrangement position of element antenna on central cross-sectional curve (3) (7)
is defined at an interval of 2D, and a virtual point (8) is a partial enlarged view of the arrangement position of the element antenna as seen from a fixed direction as a distant point from the arrangement position (7) of the element antenna. (9
) is the arrangement position of the element antenna (2) on the geodesic line (4). The arrangement position (9) of the element antenna is a point Dy interval from the arrangement position (7) on the geodesic line (4) starting from the arrangement position (7) of the element antenna on the central cross-sectional curve (3), From the virtual point (8) on the geodesic curve (4) starting from the virtual point (8), first there are points at D7/2, and then there are points at intervals of Dy.

Figures 4(a) and 4(b) show examples of constant periodic arrays of element antennas defined on a plane; (a) is a square array;
(b) is a diagram of a triangular array. Each arrangement has an arrangement period of Dy in the X' force direction Dx and the Y' direction.

Next, a method of determining the arrangement of element antennas on a curved surface that is bilaterally symmetrical with respect to the XZ plane will be explained.

As an example of FIG. 4(b), the case where the triangular arrangement on the plane is an isosceles triangle will be explained. That is, α=the arrangement position (7) of the element antenna (2) is determined. Center cross section curve (3
) is a geodesic curve, so the array period in the X direction is perfectly preserved on this curve. Further, a point DX at a distance on the curve from the arrangement position (7) of the element antenna on the central cross-sectional curve (3) is assumed to be a virtual point (8).

Next, as shown in No. 34m, a geodesic line (4) perpendicular to the XZ plane is drawn starting from the arrangement position (7) of the element antenna on the central cross-sectional curve (3) and the virtual point (8), respectively. . There is only one geodesic curve given the starting point on the curve and the direction at the starting point.

On the geodesic line starting from the arrangement position (7) of the element antenna, from the arrangement position (7) to the Dy interval, and also from the virtual point (
On the geodesic line starting from 8), first find the virtual point (8)
The point DY/2 from is set as the placement position (9), and after that, Dy
Points set at intervals.

Moreover, when the shape of the element antenna (2) to be arranged is non-rotationally symmetric, the orientation of the element antenna (2) is as follows.

Direction with respect to the Y' axis in Figure 4(b) and each geodesic line (4)
It is only necessary to arrange it so that the directions match the direction.

According to the above inventions, since the arrangement period of the element antennas arranged on a plane is secured on the geodesic curve defined on one curved ground plane, the arrangement period error of the element antennas arranged on one curved ground plane can be reduced. can. This makes it easier to control side lobes in terms of electrical performance even in conformal array antennas with curved ground planes other than spherical, making it possible to achieve low side lobe performance over a wide angle.

Further, there is an advantage that the connection of the feeding circuit of the element antenna becomes structurally easy.

〔Effect of the invention〕

As described above, according to the present invention, in a conformal array antenna in which element antennas are directly mounted on the surface of a ground plane consisting of nine curved surfaces, the position P' of each element antenna in a constant periodic array defined in advance on a plane is determined by polar coordinates. (r,
θ), and when we set orthogonal XY coordinates on the fixed point O and the tangential plane at the fixed point O on the above curved ground plane and define a geodesic line starting from the fixed point O and tangent from the X axis in the direction of θ, on the above curved ground plane By arranging each element antenna at a point P at a distance r from the fixed point O on the geodesic curve.

Arrangement position P of the element antenna on a plane with the origin O' as the pole
It is possible to match the geodetic coordinates of ' and the geodetic coordinates of the arrangement position P of the element antenna on the curved surface with the fixed point 0 as the pole,
As a result, the position P' of each element antenna in a constant periodic array defined on a plane is mapped to the arrangement position P of each element antenna on the curved ground plane, and even on curved ground planes other than one spherical surface, the array periodic error of each element antenna is A conformal array antenna with a small size can be obtained, and the degree of freedom in designing the conformal array antenna is increased.

In addition, in a conformal array antenna in which element antennas are directly mounted on the surface of a ground plane that is a curved surface that is symmetrical with respect to the XZ plane, a constant periodic array is arranged on the intersection line (center cross-sectional curve) between the above curved surface and the XZ plane. When multiple points are determined and geodesic lines perpendicular to the XZ plane are defined using these points as starting points.

By arranging each element antenna on the surface of the ground plane consisting of the above-mentioned curved surface at a constant periodic arrangement point on the above-mentioned geodesic curve, the arrangement period of the element antenna of the arrangement defined on the plane and the central cross-sectional curve and the central cross-sectional curve can be adjusted. The arrangement period can be matched with respect to the direction of orthogonal geodesics, and as a result, a conformal array antenna with a small arrangement period error of each element antenna can be obtained even on a curved ground plane other than a spherical surface.

This has the effect of increasing the degree of freedom in designing the conformal array antenna.

Fig. 24 is a partial enlarged view of the arrangement position of the element antenna when the curved ground plane (1) defined on the plane shown in Fig. 4 is viewed from two directions.

FIGS. 4(a) and 4(b) are diagrams showing examples of element antennas in a constant period array defined on a plane.

FIG. 5 is an element antenna arrangement diagram of a conventional conformal array antenna.

In the figure, (1) is the ground plane, and (2) is the element antenna.

(3) is the central cross-sectional curve of the ground plane, (4) is the geodesic curve, (5)
is the tangential plane at the fixed point O on the curved ground plane, (6) is the tangential plane at the fixed point P on the curved ground plane, (7) is the arrangement position of the element antenna on the central cross-sectional curve, and (8) is defined on the central cross-sectional curve. (9) is the placement position of the element antenna on the geodesic line (4) excluding the center section curve, (P) is the placement position of the element antenna on the curved ground plane, (P') is the plane This is the arrangement position of the upper element antenna.

In addition, in FIG. 9, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1) In a conformal array antenna in which a plurality of element antennas are arranged on the surface of a curved ground plane, each element antenna in a constant periodic array defined in advance at orthogonal X'Y' coordinates on a plane. Each position P' is represented by polar coordinates (r, θ), and orthogonal XY coordinates are determined on the ground plane made of the above curved surface at a fixed point O and on a tangential plane at the fixed point O, starting at the fixed point O and touching in the direction of θ from the X axis. A conformal array antenna characterized in that, when a geodesic line is defined, each element antenna on the surface of the ground plate made of the curved surface is arranged at a point P at a distance r from a fixed point O on the geodesic line. 2) In a conformal array antenna in which a plurality of element antennas are arranged on the surface of a ground plane made of a curved surface symmetrical to the XZ plane, on the intersection line (center cross-sectional curve) between the ground plane made of the above curved surface and the XZ plane. When a plurality of points are set in a constant periodic array on , and geodesic lines perpendicular to the XZ plane are defined with these points as starting points, each element antenna on the surface of the ground plane made of the above curved surface is arranged in a constant periodic array on the above geodesic line. A conformal array antenna characterized by being arranged at points.