JPH08973U - Circular antenna - Google Patents

Abstract

(57) [Abstract] [Purpose] A circular antenna suitable for use as a broadcasting antenna or the like, and more particularly to a circular antenna in consideration of matching between a power feeding means and a waveguide space. [Structure] A pair of metal disks 1 and 2 separated from each other are connected by a peripheral wall 4 to form a waveguide space S, and a power radiation slot 1a is formed in one of the pair of metal disks. The other metal disk 2 has a power supply opening 2a at the center thereof.
And a conical matching body 5 is concentrically arranged in the power feeding portion connected to the opening 2a with the top of the cone facing the center of the power feeding opening 2a, and the inside of the coaxial line connected to the power feeding portion is formed. The conductor 3b is connected to the apex of the cone, and the outer conductor 3a of the coaxial line is coupled to the periphery of the power feeding opening 2a to prevent the reflection of the power at the connecting portion between the coaxial line and the waveguide space S and to supply the power. It has a feature in that it can be taken out effectively.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circular antenna suitable for use as a broadcasting antenna or the like.

[0002]

[Prior art]

 As a conventional circular antenna, various types such as a coaxial type a as shown in FIG. 1 and a waveguide type b as shown in FIG. 2 have been proposed. In either case, the feeding section such as the coaxial line c or the waveguide d cannot be matched with the waveguide space e, and thus the coaxial line c or the waveguide d and the waveguide space e cannot be matched. Since the electric power is reflected at the connection part, there is a problem that the power supply cannot be taken out effectively.

In FIGS. 1 and 2, reference numeral c1 is an inner conductor of the coaxial line, c2 is an outer conductor of the coaxial line, f is an upper portion of a circular antenna with a slot g made of a metal plate, and h is a metal plate. The lower part of the circular antenna, i is the terminating resistor, and j is the feeding aperture.

[Problems to be solved by the device]

 The present invention is intended to solve the above problems, and an object of the present invention is to provide a circular antenna capable of accurately matching a feeding portion and a waveguide space. To do.

[0004]

[Means for Solving the Problems]

 For this reason, the circular antenna of the present invention has a slot for power radiation in one of the pair of metal discs in a waveguide space formed by coupling a pair of metal discs separated from each other by a peripheral wall. The other metal disk has a power supply opening at its center, and a power supply unit connected to the same has a matching body with the top of the matching body facing the center of the power supply opening. The inner conductor of the coaxial line which is arranged concentrically and is connected to the power feeding portion is connected to the top portion, and the outer conductor of the coaxial line is coupled to the periphery of the power feeding opening. There is.

[0005]

[Action]

 In the above-mentioned circular antenna of the present invention, the matching body arranged in the waveguide space acts to prevent the reflection of electric power at the connection portion between the feeding means and the waveguide space.

In addition, the matching body accurately converts the electric field direction of the supplied power by 90 °, that is, performs accurate mode conversion in the coaxial line as the power supply means and the waveguide space.

[0007]

【Example】

 Hereinafter, a coaxial circular antenna as an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a vertical cross-sectional view of the center, FIG. 4 is a vertical cross-sectional view of the center, and FIG. Is a central longitudinal cross-sectional view shown in FIG.

As shown in FIGS. 3 and 4, a pair of metal disks 1 and 2 are arranged so as to face each other while being separated from each other, and one metal disk 1 serves as an opening for radiating power. A plurality of slots (or slits) 1a are formed concentrically or spirally.

A circular feed opening 2a is formed coaxially with the metal disc 2 in the center of the other metal disc 2, and a coaxial line 3 as a feed portion is connected to the opening 2a. Has been done.

A metal peripheral wall 4 that connects the peripheral portions of the metal circular plates 1 and 2 is provided, and the metal circular plates 1 and 2 and the metal peripheral wall 4 have a metal wall inside them. An enclosed waveguide space S is formed.

By the way, in the waveguide space S, a conical metal matching body 5 having a taper surface of θ (≈45 °) is arranged with its conical top facing the opening 2a. Has been done. The arrangement of the aligning body 5 will be described in more detail. The bottom surface of the aligning body 5 is coaxially attached to the metal disk 1, and therefore the top of the aligning body 5 is on the central axis of the opening 2a. To exist in.

The outer conductor 3a of the coaxial line 3 is connected to the opening 2a, and the inner conductor 3b of the coaxial line 3 is connected to the conical top of the matching body 5.

Since the circular antenna of this embodiment is configured as described above, the conical matching body 5 does not cause power reflection at the connection between the coaxial line 3 and the waveguide space S. Therefore, the power feeding power can be effectively taken out.

In addition, the conical matching member 5 accurately changes the direction of the electric field from the direction shown by the arrow A in FIG. 4 in the coaxial line 3 to the direction shown by the arrow B in FIG. 4 in the waveguide space S. Only 90 ° can be converted, that is, accurate mode conversion is possible, which can further contribute to the extraction of effective power supply power.

By the way, as shown in FIG. 5, the thickness of the connecting end portion 3c of the inner conductor 3b connected to the conical top portion of the conical matching member 5 is made different from that of the other inner conductor portions (for example, by thinning). By further setting the length of the connection end 3c to ¼ of the line wavelength λ, the impedance Z ₀₂ squared Z ₀₂ ² at the connection end 3c feeds the line 3 to which power is fed. If the impedance Z ₀₃ and the impedance Z ₀₁ in the waveguide space S are equal to the product Z ₀₁ Z ₀₃ , that is, Z ₀₂ ² = Z ₀₁ Z ₀₃ , then the coaxial line 3 And the waveguide space S can be perfectly matched with each other, and the feeding power can be effectively taken out.

That is, the connecting end portion 3c having the thickness and length set as described above functions as an impedance matching portion.

Reference numeral 7 in FIGS. 3 to 5 indicates an annular terminating resistor.

FIGS. 6 to 15 show a coaxial type circular antenna as another embodiment of the present invention. FIG. 6 is a longitudinal perspective view of the center thereof, FIG. 7 is a longitudinal sectional view of the center thereof, and FIG. 8 is a reflection thereof. Fig. 9 is a graph showing the coefficient characteristic, Fig. 9 is a graph showing the power density characteristic along the radial direction of the upper space, Fig. 10 is a central longitudinal sectional view showing another example corresponding to Fig. 7, and Figs. Are graphs for explaining the operation of those shown in FIG. 10, and FIGS. 14 and 15 are central longitudinal sectional views showing other examples corresponding to FIG. 7, respectively, and FIGS. The same reference numerals as those in FIG. 5 indicate almost the same parts.

In this embodiment, as shown in FIGS. 6 and 7, in the waveguide space S surrounded by the metal walls, the intermediate metal plate 6 parallel to the metal disks 1 and 2 and the peripheral wall 4 are formed. A gap D for bypassing the feeding power is provided between the two, and the intermediate metal plate 6 divides the waveguide space S into two waveguide spaces S1 and S2.

The intermediate metal plate 6 is attached to the metal disc 1 via a terminating resistor 8 (which is arranged at the center of the disc), or via an insulating plate or the like on the way. The installation is performed at an appropriate location.

In the waveguide space S1, a metal cone-shaped matching body 5'having a tapered surface of θ (= 45 °) is arranged with its cone top facing the opening 2a. It is set up. That is, the bottom surface of the aligning body 5'is concentrically attached to the intermediate metal plate 6 so that the conical top of the aligning body 5'is present on the central axis of the opening 2a.

Note that the outer conductor 3a of the coaxial line 3 is connected to the opening 2a, and the inner conductor 3b of the coaxial line 3 is connected to the conical top of the matching body 5 ', which is the same as the above-described embodiment. It

In this way, also in the case of the present embodiment, the electric power at the connection between the coaxial line 3 and the waveguide space S (lower waveguide space portion S1) is produced by the action of the conical matching body 5 '. Since the reflection can be eliminated, and the coaxial line 3 and the waveguide space S can perform the mode conversion by accurately converting the electric field direction by 90 ° as shown by arrows A and B in FIG. The power feeding power can be effectively taken out into the lower waveguide space S1.

FIG. 8 shows the reflection coefficient characteristics seen from the opening 2a (connector portion). From this figure, it can be seen that the number of reflections is reduced and power can be effectively supplied.

In this way, the electric power efficiently supplied to the lower waveguide space S1 passes through the lower waveguide space S1 as shown by the arrow Pf, and the gap between the peripheral wall 4 and the intermediate metal plate 5 is reached. It bypasses D, reaches the upper waveguide space S2, and propagates toward the central portion thereof.

When the supplied power passes through the upper waveguide space S2, the power is radiated through the slot 1a formed in the metal disk 1. The power density characteristic at this time is as shown by the symbol M in FIG. This characteristic M has a substantially sawtooth shape. This is because the power density sharply decreases when power is radiated through the slot 1a. However, since power is supplied from the periphery, the level of this characteristic M as a whole is , And becomes almost the same regardless of the distance R from the end. That is, according to the circular antenna of the present embodiment, the fed power is taken into the waveguide space S without loss, and the radiated power becomes almost uniform during radiation, so that the antenna gain is greatly improved. is there.

As shown in FIG. 10, a taper is provided on the peripheral portion of the waveguide space S to facilitate the passage of radio waves, and a portion (corner portion) C including the feeding power bypass gap D is provided. You may make it match with.

With this configuration, there is no power reflection between the lower waveguide space S1 and the corner portion C, which allows the corner portion to be removed from the lower waveguide space S1. Through this, it is possible to sufficiently take in the power supply to the upper waveguide space S2.

FIG. 11 shows the state of the internal field in both waveguide space portions S1 and S2 at this time. From this graph, the internal field in both waveguide space portions S1 and S2 is almost the same. You can see that This means that there is no reflection at the corner. At this time, the impedance Zd in the lower waveguide space S1 and the impedance Zu in the upper waveguide space S2 are made equal to each other, whereby more effective power supply becomes possible.

Further, the reflection coefficient characteristic seen from the opening 2a portion (connector portion) in the one shown in FIG. 10 is as shown in FIG. 12, but the graph clearly shows less reflection. It turns out that it has been improved.

For comparison, FIG. 13 shows the reflection coefficient characteristics of the case without the matching body 5 '.

Reference numeral 8'in FIG. 10 indicates a terminating resistor.

Further, as shown in FIG. 14, the cross-sectional shape of the corner portion C is set to a half octagonal shape so that the corner portion C can be aligned. Good. Further, as shown in FIG. 15, the thickness of the connection end 3c of the inner conductor 3b is made different (for example, thinner) from the other inner conductor portions, and the length of the connection end 3c is further changed to the line wavelength λ. By setting it to 1/4 of the above, the impedance Z ₀₂ squared Z ₀₂ ² at this connection end 3c becomes an impedance Z ₀₃ in the other coaxial line (feed line) 3 and the lower waveguide space. If the product Z ₀₃ Zd with the impedance Zd in the section S1 is made equal, that is, Z ₀₂ ² = Z ₀₃ Zd, the coaxial line 3 and the lower waveguide space section S1 can be perfectly matched. Therefore, it is possible to take out the power supply power more effectively.

Also in this FIG. 15, the portion (corner portion) C of the gap D has the same shape as that in FIG. 14, and the corner portion is aligned, and furthermore, FIG. 10 and FIG. Similar to the one shown in FIG. 5, the impedance Zd in the lower waveguide space S1 and the impedance Zu in the upper waveguide space S2 are set to be equal, so that extremely effective power supply is possible. Of.

Reference numeral 4'in FIGS. 14 and 15 indicates a peripheral wall.

Further, as shown in FIG. 16, the shape of the matching bodies 5; 5 ′ may be set to have a shape such that the contour line L of the vertical cross-sectional shape changes in an exponential function or the like instead of the conical shape. At this time, the connecting end of the outer conductor 3a of the coaxial line 3 to the opening 2a may also be shaped so as to change its exponential function or the like.

Further, the matching bodies 5; 5'may be hollow or solid inside, and the matching bodies 5, 5'may be those having a metal layer on at least the surface even if they are not entirely made of metal. It should be there.

[0038]

[Effect of device]

 As described above in detail, according to the circular antenna of the present invention, in a waveguide space formed by coupling a pair of metal disks spaced apart from each other by a peripheral wall, power is radiated to one of the pair of metal disks. Slot, and the other metal disk has a feeding opening at its center, and the feeding part connected to the opening has a matching body, and the top of the matching body is the center of the feeding opening. The inner conductor of the coaxial line which is concentrically arranged toward the power feeding part is connected to the top part, and the outer conductor of the coaxial line is connected to the periphery of the power feeding opening. With a simple configuration, the following effects and advantages can be obtained. (1) The matching body prevents the reflection of the electric power at the connecting portion between the power feeding means and the waveguide space, and can effectively take out the fed power. (2) The electric field direction of the supplied power can be accurately converted by 90 °, that is, the accurate mode conversion can be performed in the coaxial line as the power feeding means and the waveguide space. (3) Since the matching body that exerts the actions and effects of (1) and (2) above is arranged in the central portion of the circular antenna, the power supplied from the power feeding unit is described above in the central portion of the circular antenna. It is accurately converted into the waveguide space by the matching body. Moreover, since there is no loss due to reflection during conversion, power can be uniformly and efficiently supplied to the waveguide space inside the circular antenna, and the gain of the circular antenna can be improved.

[Brief description of drawings]

FIG. 1 is a central longitudinal perspective view showing a conventional circular antenna.

FIG. 2 is a central longitudinal perspective view showing the conduit type circular antenna.

FIG. 3 is a central longitudinal perspective view showing a coaxial type circular antenna as an embodiment of the present invention.

FIG. 4 is a central longitudinal sectional view of the same.

5 is a central longitudinal sectional view showing the other example corresponding to FIG. 4. FIG.

FIG. 6 is a central longitudinal perspective view showing a coaxial type circular antenna as another embodiment of the present invention.

FIG. 7 is a central longitudinal sectional view of the same.

FIG. 8 is a graph showing the same reflection coefficient characteristic.

FIG. 9 is a graph showing a power density characteristic along the radial direction of the upper space.

FIG. 10 is a central vertical cross-sectional view showing another example corresponding to FIG. 7.

[Fig. 11],

[Figure 12]

FIG. 13 is a graph for explaining the operation of what is shown in FIG. 10.

[Figure 14]

FIG. 15 is a central longitudinal cross-sectional view showing another example corresponding to FIG. 7.

FIG. 16 is a partial vertical cross-sectional view showing a modified example of the matching body.

[Explanation of symbols]

 1 Metal Disc 1a Slot 2 Metal Disc 2a Feeding Hole 3 Coaxial Line 3a External Conductor 3b Inner Conductor 3c Inner Conductor Connection End 4,4 'Circumferential Wall 5,5' Matching Body 6 Intermediate Metal Plate 7,8,8 ′ Termination resistor 9 Waveguide C Corner part D Gap S Waveguide space S1, S2 Waveguide space part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiharu Ito 2-2-1 Jinnan, Shibuya-ku, Tokyo Broadcasting Center of Japan Broadcasting Corporation (72) Creator Kunitaka Arimura 2-chome Matsunami, Chigasaki-shi, Kanagawa 16 Arimura Giken Co., Ltd. (72) Inventor Naohisa Goto 6-15-1-A514 Dobashi, Takatsu-ku, Kawasaki City (72) Inventor Makoto Ando 2-12-1 Ookayama, Meguro-ku, Tokyo Tokyo Institute of Technology ( 72) Inventor Tatsuya Shirai 2-12-1, Ookayama, Meguro-ku, Tokyo Inside Tokyo Institute of Technology (72) Inventor Ryuji Teramoto 2-12-1, Ookayama, Meguro-ku, Tokyo Inside Tokyo Institute of Technology

Claims (1)

[Scope of utility model registration request] 1. A waveguide space formed by coupling a pair of metal discs separated from each other by a peripheral wall, wherein one of the pair of metal discs is provided with a power radiation slot, and
The other metal disk has a power supply opening at its center,
A matching body is provided to the power feeding portion connected to the opening, the top of the matching body is concentrically arranged toward the center of the power feeding opening, and the inner conductor of the coaxial line connected to the power feeding portion is A circular antenna, characterized in that the outer conductor of the coaxial line is coupled to the top portion and is coupled to the peripheral edge of the feeding opening.