JPH05167329A - Four-wire helical antenna - Google Patents

Abstract

PURPOSE:To control a current phase by simple constitution and to efficiently receive or radiate a circularly polarized wave. CONSTITUTION:In a first radiating member 71, radiation conductors 5, 7, an arm 13, and the lower connecting piece 77 are formed integrally by sheeting. In the radiation conductor 5, a stub 81 is formed integrally in the same manner. In a second radiating member 73, radiation conductors 9, 11, an arm 27 and the lower connecting piece 75 are formed integrally by sheeting. In the radiation conductor 11, a stub 83 is formed integrally in the same manner. A first loop constituted of the radiation conductors 7, 9, the arms 13, 27, and the lower connecting pieces 75, 77 provides capacitive impedance in used wavelength. Overall length of a second loop constituted of the radiation conductors 5, 11, the arms 13, 27 and the lower connecting pieces 75, 77 is equal to that of a first loop and set so as to be a little shorter than the used wavelength, but by adjusting the length of the stubs 81, 83, inductive impedance has the used wavelength. By adjusting the stubs 81, 83, the current phase difference of both the loops is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wire type helical antenna used in a navigation system such as GPS (Earth projection position determining system).

[0002]

2. Description of the Related Art In recent years, along with the development of information society, mobile communication and satellite communication have become popular, and navigation systems such as GPS for receiving the radio waves of an artificial satellite to detect the position and speed of a mobile have been put into practical use. ing. L for GPS
A band-polarized circularly polarized wave is used, and as a receiving antenna, a 4-wire backfire helical antenna (hereinafter simply referred to as a helical antenna), a spiral antenna, or the like has been put into practical use.

FIG. 2 is a perspective view of an example of a conventional backfire type helical antenna. A flexible substrate film 3 is wound around the bobbin 1 which is a cylindrical dielectric. The bobbin 1 has a role of holding the flexible substrate film 3 in a cylindrical shape. On the surface of the flexible substrate film 3, four spiral radiation conductors 5, 7, 9 and 11 are formed by etching.

A coaxial cable 38 is arranged at the position of the center axis of the cylinder of the bobbin 1. The coaxial cable 38 is
The coaxial center conductor 39, the insulator 41 provided around the coaxial center conductor 39, and the coaxial outer conductor 4 provided around the insulator 41.
It is composed of 3 etc.

An L-shaped arm 13 is soldered to the upper end of the coaxial center conductor 39 with a solder 45. The upper end 23 of the helical radiation conductor 5 is soldered to the one end 15 of the arm 13 with the solder 19. On the other end 17 of the arm 13, the upper end 25 of the helical radiation conductor 7 is soldered (not shown).
Being soldered by.

An L-shaped arm 27 is soldered to the upper end of the coaxial outer conductor 43 with a solder 47. The upper end 35 of the helical radiation conductor 9 is soldered to the one end 29 of the arm 27 with solder 33. At the other end 31 of the arm 27, the upper end 37 of the helical radiation conductor 11 is soldered (not shown).
Being soldered by.

Radial lower connecting pieces 49 are soldered to the coaxial outer conductor 43 by soldering. The first connecting portion 51, the second connecting portion 53, the third connecting portion 55, and the fourth connecting portion 57 of the lower connecting piece 49 are respectively provided with the radiation conductors 11.
Lower end portion 59 of the radiation conductor 7, lower end portion 61 of the radiation conductor 7, lower end portion 63 of the radiation conductor 5, lower end portion 65 of the radiation conductor 9.
Is soldered. 67 and 69 are solders. The radiation conductors 5, 7, 9 and 11 are helically formed so as to wind around the bobbin 1.

The operation of the helical antenna shown in FIG. 2 will be described below. Radiation conductors 5, 11 and arms 13, 27
And the total length of the first loop constituted by the lower connection piece 49 is set to be slightly longer than the wavelength used, and the second loop constituted by the radiation conductors 7 and 9 and the arms 13, 27 and the lower connection piece 49. Is set to be slightly shorter than the wavelength used by the second loop, and the longer first loop exhibits inductive impedance and the shorter second loop operates at the used wavelength.
The loop of presents a capacitive impedance.

Therefore, by providing an appropriate difference in the total length of both loops, the radiation conductors 5, 7, 9 which are adjacent to each other, although both loops are fed in parallel,
It is possible to have a phase difference of 90 degrees between the currents flowing in and 11, and circularly polarized waves are efficiently radiated or received.

As a method of providing a difference in the total length of the loop, there is known a method of changing the pitch angle of the loop as in JP-A-63-26004. A method disclosed in JP-A-2-127804 is known as a method for changing the current phase on the helix by disposing a non-excited object near the exciting conductor.

[0011]

However, in the prior art, the structure for realizing the desired loop length and controlling the phase of the current is complicated. In some cases, it is difficult to assemble. Furthermore, it is difficult to change the current phase of the helix after assembling as an antenna.

[0012]

According to the present invention, a first radiation conductor which forms a helix is integrally formed.
Combining the radiating member and a second radiating member of similar construction,
A stub is integrally formed with the loop including at least one radiation conductor.

[0013]

[Operation] By providing a stub in parallel with a part of the radiating conductor, the current phase of the helix changes depending on the length and width of the stub. Therefore, by adjusting the shape of the stub, after the helix is assembled as an antenna, It is possible to change the current phase. Further, since the stub is formed integrally with the helix, it is easy to manufacture.

[0014]

1 is a perspective view of an embodiment of a four-wire helical antenna according to the present invention.

The first radiation member 71 is composed of the radiation conductors 5 and 7.
The arm 13 and the lower connecting piece 77 are integrally formed by sheet metal working. In the radiation conductor 5, stubs 81 are integrally formed in parallel at appropriate positions.

The second radiation member 73 includes radiation conductors 9 and 1.
1, the arm 27, and the lower connecting piece 75 are integrally formed by sheet metal working. The radiating conductor 11 is provided with stubs 83 integrally formed in parallel at appropriate places.

First and second radiating members 71 and 73
Are fixed to the support cylinder 85 so that they face each other, and the lower connecting pieces 75 and 77 are soldered (not shown).
The microstrip line substrate 7 for impedance matching is soldered to the arm 13.
One end of the strip line 93 on the surface of 9 is soldered by the solder 87, and one end of the ground plate 95 on the back surface of the micro strip line substrate 79 is soldered to the arm 27.
9 and the other end of the strip line 93 is soldered to the upper end 39 of the coaxial center conductor 39.
-1, and the other end of the ground plate 95 is soldered to the upper end of the coaxial outer conductor 43 by solder (not shown).

The operation of the helical antenna shown in FIG. 1 will be described below. The total length of the first loop formed by the radiation conductors 7 and 9 and the sides of the arms 13 and 27 and the sides of the lower connection pieces 75 and 77 is set to be slightly shorter than the wavelength used, and The one loop presents a capacitive impedance. On the other hand, the radiation conductors 5, 11
The total length of the second loop formed by the other side of the arms 13 and 27 and the other side of the lower connecting pieces 75 and 77 is set to be slightly shorter than the wavelength used equivalently to the first loop. The stubs 81 and 83 provided with the respective loops function as open stubs, and by adjusting the length of the stub 81 or 83,
The impedance of the loop of changes in and the second loop exhibits an inductive impedance at the wavelength used.

Therefore, by providing a parallel stub having an appropriate length in one of the two loops having the same length,
The currents flowing through the radiation conductors 5, 7, 9 and 11 adjacent to each other can have a phase difference of 90 degrees from each other, and circularly polarized waves can be efficiently received or radiated.

Therefore, it is difficult to realize a desired loop length by the conventional method of providing an appropriate difference in the total length of the two loops, but according to the present invention that the stubs are provided in parallel. The stub length can be easily adjusted by assembling it as an antenna and then cutting it, so that a phase difference of 90 degrees can be easily realized.

Here, the mounting positions of the stubs 81 and 83 are
In the case of the present embodiment, the vicinity of the central portions of the radiation conductors 5 and 11 where the electric field is maximum is effective, and the amount of phase change with respect to the change of the stub length is relatively small, and the phase can be easily controlled. Ends of conductors 5 and 11, or arm 1
A stub may be attached to 3, 27 or the lower connecting pieces 75, 77 to adjust the phase.

In the present embodiment, the first loop length and the second loop length are equal, but by providing an appropriate difference between the first and second loop lengths and combining this with the parallel stub. It is also possible to adjust the phase of the current.

Further, the number of stubs to be attached is not limited to one for each radiation conductor, and a plurality of stubs may be attached, or parallel stubs may be provided in both the first and second loops to adjust the respective stub lengths. Thus, the phase of the current can be controlled, and thereby the resonance frequency at which the phase difference between the currents of the adjacent radiation conductors becomes 90 degrees can be changed. Further, the directivity can be changed by changing the current distribution on the helix with the stub.

[0024]

As described above, according to the present invention, the current phase can be controlled by the stub formed integrally with the helix on the helix, so that the circularly polarized wave can be efficiently radiated or emitted with a simple structure. Can be received. Also,
After assembling as a helix antenna, it is possible to easily change the current phase by adjusting the length of the stub.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a perspective view of a conventional example.

[Explanation of symbols]

 5,7,9,11 Radiating conductor 13,27 Arm 38 Coaxial cable 39 Coaxial center conductor 41 Insulator 43 Coaxial outer conductor 71 First radiating member 73 Second radiating member 75,77 Lower connecting piece 81,83 Stub

Claims (1)

[Claims] 1. A stub is formed in a loop including at least one radiating conductor by connecting a first radiating member integrally formed with two radiating conductors forming a helix and a second radiating member having a similar structure. A four-wire helical antenna characterized by being integrally formed.