JPS5914922B2 - lens antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens antenna using the Luneberg lens principle, and more particularly to a lens antenna in which mutually opposing lens surfaces are formed into flat surfaces.

The antenna of the present invention uses the Luneberg lens principle, and the Luneberg lens generally refers to a lens made of a dielectric material with a refractive index distribution that satisfies the following formula.

n: refractive index of derivative ε: dielectric constant of dielectric γ.

: Radius of spherical or cylindrical dielectric γ: Distance from center or central axis of dielectric
A thin cylindrical Luneberg lens has the property of concentrating parallel light rays incident in any diametrical direction of a dielectric material on the diametric end opposite to the direction of arrival.

FIG. 1 is a cross-sectional view of the Luneberg lens.

L is a spherical or cylindrical Luneberg lens whose rotation axis is perpendicular to the plane of the paper, and when parallel light rays or radio waves W strike this lens, the light rays or radio waves are concentrated in the same phase at point 01 on the opposite side to the direction of arrival.

Utilizing this property, it is possible to construct a transmitting/receiving antenna or a direction finding antenna that has sharp directivity in any direction.

The well-known wire grid lens antenna shown in FIGS. 2 and 3 is one example.

The principle of this wire grid lens antenna is that when a Luneberg lens is constructed of two wire meshes and the wire meshes are arranged parallel to each other at a predetermined interval sufficiently small for the wavelength of the radio wave used, the two wire meshes The equivalent dielectric constant ε=n2 of this lens for radio waves propagating between wire meshes is 2, and the equivalent permittivity ε-n2 when the wire meshes are arranged parallel to each other at large intervals relative to the wavelength of the radio waves used is based on the fact that 1.

It is known that this principle holds true regardless of whether the mesh shape of the wire mesh is a regular triangle, a square, or a regular hexagon.

In the wire grid lens antennas illustrated in FIGS. 2 and 3, each wire mesh has a diameter AB
One of the main lenses 2 is supported by a pole 4 as appropriate, and the other can be replaced with any ground surface 6.

The distance between the two wire meshes at the center of the lens 2 is narrow, and the distance increases toward the periphery, thus obtaining the dielectric material necessary for the Luneberg lens.

Further, a group of conductive wires 1 extending along the generatrix of the double cone of the lens 2 constitutes an electromagnetic horn that has the function of receiving and receiving incoming radio waves 5 and effectively transmitting the radio waves 5 to the lens portion.

The wire grid lens antenna operates so that all incoming radio waves 5 consisting of parallel beams are concentrated on the opposite diameter end 3 of the lens 20 in the same phase.

Therefore, since the reception field strength at this diameter end 3 is extremely large, by appropriately arranging a pick amplifier antenna there, the radio waves 5 can be received satisfactorily.

The above phenomenon is true regardless of the direction of the incoming radio waves 5, so by arbitrarily arranging multiple Ml pickup antennas in the peripheral area corresponding to the focal point of the lens 2, it is possible to effectively receive radio waves arriving from any direction. .

In other words, it functions as a radio wave direction finder.

By the way, in the above-mentioned wire grid lens antenna, in order to construct an antenna that has a wide band for short waves, a large gain, and sharp directivity characteristics, both the lens 2 and the electromagnetic horn 1 must be adjusted considerably. It is necessary to configure it with a large diameter.

Therefore, if you build such an antenna on the ground,
This is an extremely large-scale device.

In addition, the work required to properly adjust the distance between the lens parts 20 depending on the construction site and to fully demonstrate the performance of the Luneberg lens becomes considerably difficult as the antenna scale increases. Construction of such antennas requires a huge amount of money.

An object of the present invention is to provide a lens antenna that solves the above-mentioned drawbacks.

Another object of the present invention is to provide a lens antenna that can easily construct a transmitting/receiving antenna with an excellent lens function and also has a good antenna function.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

In FIG. 4, 6a is a required depth from the ground surface 6, and is, for example, a semi-underground surface excavated horizontally in a circular shape.

The peripheral part of this semi-underground surface 6a is formed so as to transition to the ground surface 6 through an inclined surface section 6b having an appropriate inclination, making it convenient for maintenance of the equipment and other operations at the inclined surface section 6b.

Reference numeral 7 denotes a lens section installed on the semi-underground surface 6a so as to be close to the height of the ground surface 6, and this lens section has a diameter larger than the wavelength of the radio waves used.

As shown in FIGS. 5 and 6, this lens portion 7 is
A circular lower lens body 7b is provided, which is formed by appropriately metallizing the semi-underground surface 6a itself or the surface 6a by covering it with a wire mesh or a thin plate.

On this lens lower surface body 7b, a lens upper surface body 7a facing the lens lower surface body 7b at a parallel interval is disposed at a height that is close to the ground surface 6 or at a height equivalent to y.

This upper lens body 7a is made of a wire mesh or a thin plate, and has the same diameter as the lower lens body 7b, and the distance between it and the lower lens body 7b is set to be smaller than the wavelength of the radio waves used.

And between these lens upper and lower surfaces 7a and 7b,
A plurality of dielectric rods 8, which are dielectric members having a dielectric constant of 5 or more and arranged in the manner described later, are appropriately interposed vertically to serve as a separator between the lens upper and lower surfaces 7a and 7b.

As an example of this method of interposing the dielectric rods 8, as shown in FIGS. ) In order to satisfy the dielectric relationship of the equation, the lens portion 7 is divided into a number of concentric annular regions, and the equivalent relative dielectric constant near the center is 2.
The arrangement density of the rods is uniformly set so that

Radius γ of the outer periphery of the lens part.

Since the amount of dielectric material required is large, it seems that the amount of dielectric material required increases significantly, but since vertically polarized waves inside the lens can propagate as TEM waves in directions parallel to both the upper and lower surfaces, even if the outer periphery of the lens is large, Since the height can be made smaller than the wavelength, the number of dielectric rods 8 used is large (although the required cost is not large).

Examples of dielectric materials include hard polyvinyl chloride, dielectric constant 2.3 to 3.1, polyethylene 2.2 to 2.4, etc.
You can select and use the appropriate one.

As a specific arrangement mode of the dielectric rod 8, for example, FR
When applying to short waves using a P rod or pipe C (diameter approximately 100 mmφ) as the dielectric rod 8, the lens upper surface body 7
Assuming that the diameters of the lens a and the lower lens body 7b are 60 m, and the height of the lens portion is 4 m, the dielectric rods 8 are arranged in close contact within a radius of 1 m from the center.

Then, in a portion with a radius of 10 m, one wire is arranged for every 10 degrees of azimuth.

In the area with a radius of 20 m, there is one wire for every 10 degrees of azimuth.
Further, in the peripheral part with a radius of 60 m, one wire is arranged for every 30 degrees of azimuth.

Also for these intermediate positions, n2==This causes the dielectric constant to change depending on the distance from the center of the lens section 7, thereby converging the incoming radio waves to the focal point of the lens section 7 in the same phase.

As a means to prevent incoming radio waves from being introduced into the lens section 7,
According to the present invention, the radio wave guiding antenna 11 consisting of a plurality of single vertical antennas arranged at equal intervals is installed on the ground surface 6 near the outer periphery of the lens portion 7 and close to the inclined surface portion 6b. It is.

Reference numeral 9 denotes an electromagnetic coupling device consisting of a coil or a loop, which is connected to the periphery of the lens portion 7 in correspondence with the installation position of the antenna 11 through a feeder line 10 connected to each of the antennas 11 separately. It is arranged.

This electromagnetic coupling device 9 functions to effectively convert the output of the antenna 11 into radio waves within the lens portion γ.

Furthermore, a plurality of pickup antennas (not shown) are installed at the focal point within the lens portion 7 in conjunction with the electromagnetic coupling device 9 using conventional means.

It is of course possible to install these pickup antennas so that they can be selectively switched as appropriate.

In the above, since the radio wave guiding antenna 11 can be of a small size, it is also possible to replace it with a wave antenna 13 extending radially from the center of the lens portion 7, as illustrated in FIG.

In such a case, these wave antennas 13 may be connected to the respective electromagnetic coupling devices 9 through the feeder lines 12 along the gently sloped surface portion 6b'.

A specific example of the radio wave induction antenna 11, the electromagnetic coupling device 9, and the pick amplifier will be explained with reference to FIG.

Reference numeral 14 denotes a vertical receiving antenna having an insulated base and having a length of about 4 m, which corresponds to the radio wave guiding antenna 11 shown in FIG.

Reference numeral 15 denotes an electromagnetic coupling device supported by an insulator 16, into which received power is introduced via a coaxial feeder line 17.

The vertical reception antenna 14 and the electromagnetic coupling device 15 include a matching box (not shown) for matching the feed line 17.

18 is a dielectric rod disposed between the lens upper surface body 7a and the lens lower surface body 7b made of a metal plate or metal mesh;
It is supported by an insulating branch line 19.

A pink-up antenna 20 is provided facing the electromagnetic coupling device 15 across the lens portion I, and has a length of about 2 m.

21 is a coaxial cable for guiding the power received by the pickup antenna 20 to a receiver (not shown) through a switching device or the like.

Received power from a plurality of pickup antennas 20 disposed around the lens portion 7 is collected at one location by a coaxial cable 21.

In this way, due to the focusing effect of the radio waves by the lens, the radio waves are most strongly received by the pickup antenna 20 provided on the opposite side of the direction of arrival of the radio waves with the lens at the center.

Therefore, by switching the reception outputs of the plurality of pickup antennas 20 arranged around the lens section 7, the magnitude of the reception power can be identified.

That is, it is possible to know the direction in which the radio waves arrive.

This works as a direction finder.

FIGS. 10 and 11 show other embodiments of the present invention, and the same parts as in FIG. 7 are given the same reference numerals and their explanations are omitted.

In this case, the lens portion 7' has a cylindrical shape, and the lens upper surface 7'a, the lens lower surface 7'b, and the side surfaces 7'c are made of a good electrical conductor.

Vertical receiving antennas 1 are installed at regular intervals around the cylindrical outer wall.
4 is arranged, and the capacitor 22 of the tuning circuit of this vertical reception antenna 14 is arranged inside the cylinder.

Coils (not shown) forming the 220 pairs of capacitors are housed in the receiver 23.

As shown in FIG. 12, these capacitors 22 act as point sources of TEM waves, generate TEM waves with wavefronts such as F in the cylinder, and concentrate the receiving power at 01.

By adjusting each antenna and receiver all at once to receive a predetermined radio wave in this way, it is possible to concentrate the power received by each antenna on the receiver located on the opposite side of the direction in which the radio wave arrives.

Since there is no concentration effect on radio waves in other directions, sharp directional reception is possible.

In the lens antenna according to the present invention, the lens upper body is stretched to the lower lens body at uniform intervals and close to the ground surface, so that the lens part can be easily constructed in combination with the use of dielectric members. In addition, it can be used as a transmitting/receiving antenna or a radio wave direction detection antenna with sharp directivity in any direction.

Further, the lens antenna of the present invention is convenient because it can be easily installed by digging into the ground, and there is no fear that it will be detected from the outside when used for direction finding.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a Luneberg lens, FIG. 2 is a conceptual plan view of a well-known circular wire grid lens antenna, FIG. 3 is a front view thereof, and FIG. 4 is a conceptual diagram of a lens antenna according to the present invention. 5 is a conceptual partial front view showing the details of the installation mode, FIG. 6 is a similar partial front sectional view showing another example of the radio wave induction antenna, and FIGS. 7 and 8 are dielectric FIG. 9 is a conceptual diagram showing specific examples of a radio wave induction antenna, an electromagnetic coupling device, and a pickup antenna. FIGS. A conceptual front view and a plan view showing another embodiment, and FIG. 12 are conceptual diagrams showing a wave front of a wave traveling within a two-dimensional Luneberg lens. 6...Ground surface, 6a...Semi-underground surface, 7
... Lens part, 7a ... Lens upper surface body, 7b ... Lens bottom surface body, 8, 18 ...
・Dielectric rod, 9, 15... Electromagnetic coupling device, 10
, 12, 17...Feeding line, 11...Radio wave induction antenna, 14...Vertical reception antenna, 20...Pickup antenna.

Claims (1)

[Claims] 1 The lens portion 7 is composed of a disk-shaped upper surface body 7a and a lower surface body 7b, which are formed of a thin metal plate or a fine metal mesh and have a diameter larger than the wavelength of the radio waves used, and these upper surfaces The body 7a and the lower body 7b are opposed to each other with an interval smaller than the wavelength of the radio waves used, and the upper and lower body 7a
A large number of thin dielectric rods 8, 18 having a relative permittivity of greater than 2 are arranged between each other, and these dielectric rods 8, 18
The central regions of the upper and lower surfaces 7a and 7b are dense and become coarser as they approach the peripheral regions to form a two-dimensional Luneberg lens, and the peripheral portions of the Luneberg lenses are arranged in a circumferential direction. Vertical receiving antenna 1 at regular intervals along
1 and 14, and elements of the tuning circuit of the vertical receiving antennas 11 and 14 are arranged between the upper and lower surface bodies 7a and 7b, and the receiving force by the vertical receiving antennas 11 and 14 is determined by the Luneberg lens. A lens antenna that focuses on a specific point.