JP2001102852A - Helical antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable miniaturization suitable for portability. SOLUTION: Plural helical elements 11-14 are helically formed on the outer peripheral surface of a cylindrical insulated main body 2 of an antenna. The said respective plural helical elements 11-14 at a prescribed winding angle are formed being bent in the shape of cyclic waveform with a winding angle line Lα as a center line. Thus, a full length h1 of a helical antenna 11 can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical antenna suitable for mounting on satellite communication equipment.

[0002]

2. Description of the Related Art Various satellite communication systems for mobile communication have been proposed. The satellite communication system includes a geostationary mobile satellite communication system using geostationary satellites and a non-geostationary mobile communication system using non-geostationary satellites. There is a satellite communication system. Non-geostationary mobile satellite communication systems include a system using satellites in low and medium altitude orbits, a system using satellites in oblong orbit, and a system using tilt-synchronous orbit. Among the systems using non-geostationary satellites in low and medium altitude orbits, L
There is an EO (Low Earth Orbit) communication system. This L
The EO communication system is a system in which the propagation delay time is small and the propagation loss is reduced, so that the EO communication system has an advantage that the transmission power of the terminal can be reduced and the terminal can be easily reduced in size and weight. .

Further, the LEO communication system includes a small LEO (Little LEO) that handles only data transmission.
And large-scale LEO (Big LEO) capable of voice transmission
There is. Among the large LEOs are the Iridium system and the ICO (Intermediate Circular Orbit) system (Project 21). The Iridium system uses a TDMA (Ti
The communication is performed using (66 + 6) non-geostationary satellites launched at an altitude of 780 km to cover the entire earth. These non-geostationary satellites orbit at 30 degrees longitude and orbit. In addition, the ICO system has six orbiting satellites each arranged in a 10390 km orthogonal oblique orbit. The mobile terminal is a dual terminal that can be shared with the satellite network using satellites and the existing terrestrial mobile phone system. Have been.

In such a satellite mobile communication system, although a large number of satellites are required, communication delay time can be ignored, so that voice and data communication can be performed in real time. Further, since the transmission power of the terminal can be reduced, the terminal can be made portable. Therefore, if a portable wireless device for a satellite mobile communication system is carried, it becomes possible to perform real-time communication and data transmission with telephones and mobile telephones all over the world. In the satellite mobile communication system, circularly polarized waves are used so as to be suitable for portable radios.

[0005] By the way, in a portable radio for a satellite mobile communication system, a helical antenna or a microstrip antenna capable of transmitting and receiving circularly polarized waves is used because it is necessary to receive circularly polarized waves. Here, the configuration of a conventional helical antenna capable of transmitting and receiving circularly polarized waves is shown in FIGS. FIG. 6 is a diagram showing a configuration of the helical antenna 100, and FIG. 7 is a developed view in which the antenna main body 102 is developed. As shown in FIG.
00 denotes an insulating cylindrical antenna body 102
And a phase delay circuit 103 including a matching circuit that delays the phase and feeds power to the helical elements 111, 112, 113, and 114 provided on the outer peripheral surface of the antenna body 102.
And a power supply unit 104.

[0006] Four helical elements 111 to 114
When the antenna main body 102 having the helical elements 102 is expanded, as shown in FIG.
Are wound around the antenna main body 102 at a winding angle α. Four helical elements 111
The winding start ends of .about.114 are respectively a, b, c, d, and the winding end ends are a ', b', c ',
d '. The winding start ends a, b, c, and d are arranged at equal intervals (approximately 90 °).
b, c, and d are supplied with a signal from a power supply unit 104 delayed by a predetermined amount from a phase delay circuit 103 including a matching circuit. For example, a signal delayed by 0 ° at the winding start end a, a signal delayed by 270 ° at the winding start end b,
A signal delayed by 180 ° is supplied to the winding start end c, and a signal delayed by 90 ° is supplied to the winding start end d. In this way, by supplying signals to the four helical elements 111 to 114 with phases delayed by approximately 90 ° in the counterclockwise direction, right-handed circularly polarized waves are radiated from the antenna main body 102. Further, by reversing the winding relationship of the helical element and the phase relationship of the phase delay circuit, left-handed circularly polarized waves can be emitted.

[0007]

The conventional helical antenna shown in FIGS. 6 and 7 has an antenna body 1 due to its configuration.
02 has a problem that when it is applied to a portable device of a satellite mobile communication system, the overall configuration becomes large. Since portable devices are required to be as small as possible, it is an object of the present invention to provide a miniaturized helical antenna with excellent portability when mounted on portable devices of a satellite mobile communication system. And

[0008]

In order to achieve the above object, a helical antenna according to the present invention comprises a plurality of helical elements wound helically on the outer peripheral surface of a cylindrical insulating antenna body. Wherein the plurality of helical elements having a helical shape with a predetermined winding angle are bent and formed into a periodic wave shape with the winding angle line having the winding angle as a center line. ing.

In the helical antenna according to the present invention, each of the helical elements may have a triangular waveform. Further, in the helical antenna of the present invention, the shape of each helical element may be a sine wave. Furthermore, in the helical antenna according to the present invention, when an angle between a tangent line of each of the helical elements and a normal to the center line at an intersection of each of the helical elements and the center line is β, 0 ° < β <90 ° may be satisfied.

According to the present invention, each helical element of the plurality of helical elements is formed so as to be bent into a periodic wave shape having a winding angle wire having a winding angle as a center line. Therefore, the total length of the antenna main body can be shortened. This makes it possible to reduce the size of the helical antenna and to provide a helical antenna suitable for mounting on a portable device of a satellite mobile communication system.

[0011]

FIG. 1 shows a first configuration of an embodiment of a helical antenna according to the present invention. FIG. 2 is a development view of the antenna main body in the helical antenna shown in FIG. As shown in FIG. 1, the helical antenna 1 has a cylindrical antenna body 2 having an insulating outer diameter φo and helical elements 11, 12, 13, 14 provided on the outer peripheral surface of the antenna body 2. And a power supply unit 4. In addition,
Helical elements 11, 12, 1 in phase delay circuit 3
A matching circuit that matches the power supply units 4 with the power supply units 4 may be included. 4 helical elements 11-1
When the antenna main body 2 provided with the antenna element 4 is developed, it becomes as shown in FIG. 2, and the four helical elements 11 to 14 are each bent into a triangular wave shape which is a periodic waveform with the winding angle L _α having the winding angle _α as the center line. It can be seen that the antenna is wound around the antenna main body 2.

[0012] The four helical elements 11 to 14 are the same shape, taking the helical element 11 as an example, the winding angle line L _alpha and helical element winding angle alpha, which is the center line as shown Assuming that the angle between the tangent to the helical element 11 at the intersection with the normal 11 and the normal to the winding angle line L _α (center line) is β, β is 0 ° <β <9.
0 °. The angle of the triangular wave top of the helical element 11 is 2β. The four helical elements 11 to 14 are formed by attaching a conductive thin film to the outer peripheral surface of the antenna body 2 having a cylindrical shape,
It is formed by etching a conductive thin film formed on the entire outer peripheral surface of the antenna body 2. As described above, since the first helical antenna 1 of the present invention is formed by bending the four helical elements 11 to 14 into a triangular waveform, the total length h1 of the helical antenna 1 is
Can be made shorter than the conventional helical antenna. Note that, instead of bending in a triangular waveform, the top of the triangular waveform may be bent in a trapezoidal shape.

The winding start ends of the four helical elements 11 to 14 are a, b, c, and d, respectively, and the winding end ends are a ', b', c ', and d', respectively. The winding start ends a, b, c and d are almost equally spaced (approximately 9
0 °), and a feeding portion 4 delayed by a predetermined amount from the phase delay circuit 3 at the winding start ends a, b, c, and d.
Is supplied. For example, a signal delayed by approximately 0 ° at the winding start end a, and a signal approximately 270 at the winding start end b.
The signal delayed by about 180 ° is supplied to the winding start end c, and the signal delayed by about 90 ° to the winding start end d. In this way, by supplying signals to the four helical elements 11 to 14 with phases delayed by approximately 90 ° in the counterclockwise direction, right-handed circularly polarized waves are radiated from the antenna body 2. Further, by reversing the winding direction of the helical elements 11 to 14 and the phase relationship of the phase delay circuit 3, a left-handed circularly polarized wave can be radiated from the antenna body 2. As described above, the first helical antenna of the present invention can be a suitable antenna applied to a portable device of a satellite mobile communication system.

Next, FIG. 3 shows a second configuration of the helical antenna according to the embodiment of the present invention. FIG. 4 is a development view of the antenna main body in the helical antenna shown in FIG. As shown in FIG. 3, the helical antenna 31 includes a cylindrical antenna body 32 having an insulating outer diameter φo and helical elements 41, 42, 43, 44 provided on the outer peripheral surface of the antenna body 32. It comprises a phase delay circuit 33 that delays the phase and feeds power, and a feed unit 34. Note that the helical element 4
A matching circuit for matching the power supply unit 34 with the power supply unit 34 may be included. When the antenna main body 32 provided with the four helical elements 41 to 44 is expanded, the antenna body 32 becomes as shown in FIG.
1-44 is seen to be bent winding angle line L _alpha of winding angle alpha respectively sinusoidally a periodic waveform as centerline are wound antenna body 32 wound.

The four helical elements 41 to 44 are the same shape, taking the helical element 41 as an example, the winding angle line L _alpha and helical element winding angle alpha, which is the center line as shown Assuming that the angle between the tangent of the helical element 41 at the intersection with 41 and the normal of the winding angle line L _α (center line) is β, β is 0 ° <β <9.
0 °. Four helical elements 41 to 4
4 is formed by sticking a conductive thin film on the outer peripheral surface of the cylindrical antenna main body 32 or by etching the conductive thin film formed on the entire outer peripheral surface of the antenna main body 32. ing. Although the four helical elements 41 to 44 are bent in a sine wave shape, the present invention is not limited to this, and it is sufficient that the four helical elements be bent in a periodic curve shape. As described above, since the second helical antenna 31 of the present invention is bent in a curved shape to form four helical elements 41 to 44, the total length h2 of the helical antenna 31 is shortened compared to the conventional helical antenna. Will be able to

The winding start ends of the four helical elements 41 to 44 are a, b, c, d, respectively, and the winding end ends are a ', b', c ', d', respectively. The winding start ends a, b, c and d are almost equally spaced (approximately 9
0 °), and the winding start ends a, b, c, and d are supplied with a signal from the feeding unit 34 delayed by a predetermined phase amount from the phase delay circuit 33. For example, a signal delayed by approximately 0 ° at the winding start end a, and a signal delayed by approximately 2 ° at the winding start end b.
The signal delayed by 70 ° is approximately 180 ° at the winding start end c.
The delayed signal is supplied to the winding start end d with a signal delayed by approximately 90 °. In this way, by supplying signals to the four helical elements 41 to 44 with a phase delayed by approximately 90 ° in the counterclockwise direction, right-handed circularly polarized waves are radiated from the antenna main body 32. The winding direction of the helical elements 41 to 44 and the phase delay circuit 3
3 by reversing the phase relationship of
Can also radiate left-handed circularly polarized light. in this way,
The second helical antenna of the present invention can also be a suitable antenna applied to a portable device of a satellite mobile communication system.

Next, FIG. 5 shows the directivity in the vertical plane of the first helical antenna 1 of the present invention shown in FIG. However, the winding angle α of the helical antenna 1 is about 65 °, β is about 60 °
Is the directivity in the vertical plane when Looking at the directivity shown in FIG. 5, it can be seen that the directivity of the conventional helical antenna 100 shown in FIG. The above-mentioned helical antenna of the present invention can be used not only for right-handed or left-handed circularly polarized waves but also for linearly polarized waves. In the above description, the antenna main body 2 (32) has a cylindrical shape, but the antenna main body 2 (32) is not limited to a cylindrical shape, and may have a polygonal shape such as a hexagon or an octagon. The antenna body 2 (32) is made of ABS resin (Acrylonitrile
Butadiene Styrene Copolymer), polycarbonate,
It can be formed of an insulating material such as polyacetal, polypropylene, or polytetrafluoroethylene, or a flexible base material such as polyimide.

Further, four helical elements 11 to 1
4 (41-44) winding end ends a ', b', c ',
d 'is opened as shown in the figure, but the winding end a' and the winding end c 'are short-circuited, and the winding end b' and the winding end d 'are short-circuited. You may. Further, the number of helical elements is not limited to four, but may be one or two. The helical antenna 1 (31) of the present invention is not limited to a portable terminal antenna for a satellite mobile communication system.
The present invention can be applied to a vehicle-mounted antenna and a ship antenna.

[0019]

As described above, in the helical antenna of the present invention, each helical element of a plurality of helical elements is bent into a periodic wave shape having a winding angle wire having a winding angle as a center line. Since the antenna body is formed, the overall length of the antenna body can be shortened. Thereby, the helical antenna can be reduced in size, and a helical antenna suitable for mounting on satellite communication equipment can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a helical antenna according to the present invention.
FIG. 3 is a diagram showing an example of the configuration.

FIG. 2 is a development view of an antenna main body in the first helical antenna of the present invention.

FIG. 3 shows a second embodiment of the helical antenna according to the present invention.
FIG. 3 is a diagram showing an example of the configuration.

FIG. 4 is a developed view of an antenna main body in the second helical antenna of the present invention.

FIG. 5 is a diagram showing directivity in a vertical plane of the first helical antenna of the present invention.

FIG. 6 is a diagram showing a configuration example of a conventional helical antenna.

FIG. 7 is a development view of an antenna body in a conventional helical antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Helical antenna 2 Antenna main body 3 Phase delay circuit 4 Feeding part 11, 12, 13, 14 Helical element 31 Helical antenna 32 Antenna main body 33 Phase delay circuit 34 Feeding part 41, 42, 43, 44 Helical element 100 Helical antenna 102 Antenna main body 103 phase delay circuit 104 feeding unit 111, 112, 113, 114 helical element

Claims (4)

[Claims] 1. A helical antenna comprising a plurality of helical elements wound helically on an outer peripheral surface of a cylindrical insulative antenna main body, wherein the helical antenna has a predetermined winding angle. A helical antenna, wherein each of the plurality of helical elements is formed to be bent into a periodic wave shape with the winding angle line having the winding angle as a center line. 2. The helical antenna according to claim 1, wherein each of the helical elements has a triangular wave shape. 3. The helical antenna according to claim 1, wherein each of the helical elements has a sinusoidal shape. 4. When the angle between the tangent of each helical element and the normal to the center line at the intersection of each helical element and the center line is β, 0 ° <β
The helical antenna according to claim 2, wherein the angle is set to <90 °.