JPH11136021A - Multimode antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna shape which is suitable for a field of a personal communication and can be miniaturized. SOLUTION: This device includes a helical type antenna which is formed by winding N pieces of wires 1 around a cylinder 2 which can permeate an electromagnetic wave to generate a circularly polarized wave and a mono-pole type antenna 3 that is provided in the helical type antenna along its central axis. The N pieces of wires are respectively connected to outputting parts 7 of a feeder 5 that has one inputting part 6 and N pieces of the outputting parts 7 with appropriate forms about phase and amplitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a multi-mode antenna for a mobile communication system.

[0002]

2. Description of the Related Art An antenna of this type will be described with reference to FIGS. In FIG. 8, a first example is a mode in which a monopole type antenna 16 is installed on a handy phone 17, and such an antenna is described in a mobile antenna system handbook (Fujimoto and James, Artech House 1994, pp. 154).
-155). On the handy phone 17, a helical antenna 18 is disposed at a distance D from the antenna 16.
111, and such a helical antenna 18 is provided in a mobile antenna system handbook (Fujimoto and James, Arttech House 1).
994, pp455-457).

[0003] This kind of monopole type antenna is
Provided for terrestrial communication systems (such as GSM), helical antennas are provided for circularly polarized satellite communication systems. Distance D111 should be optimized such that there is no perturbation in each diagram.

[0004] In FIG. 9, another example is a handy phone 1.
7 is provided with a PIFA type antenna 20 on the rear surface thereof. Such an antenna is described in a mobile antenna system handbook (Fujimoto and James, Art, Art.
ech House 1994, pp 235-239)
It is described in. In this example, a helical antenna 18 similar to the first example is installed at a distance from the antenna 20.

A PIFA type antenna 20 is provided for a terrestrial communication system (such as GSM), and a helical antenna is provided for a circularly polarized satellite communication system. The placement of each antenna should be optimized for optimal performance.

[0006]

However, the above-mentioned antenna has the following problems.

A first problem is that a large space is required for installing two antennas, which is not suitable for a small portable communication device. Also, the manufacturing cost increases. This is because it is necessary to consider the separation of the two interacting antennas based on the structure of the device, since it requires a long search and trimming time.

[0008] The second problem is that most structures are large in volume and size, which is fatal in mobile communications. When two or more antennas have to be used, they should be combined. Upon receiving a call on the handy phone, the user must decide whether to pull out a satellite or terrestrial antenna. This is impractical. This is because in order to have multiple operating frequencies and polarizations, some proposed solutions have to be applied to two different structures, increasing the number of required frequencies and taking up space. is there.

It is an object of the present invention to solve the above-mentioned problems and to provide a compact antenna form suitable for the field of personal communication.

[0010]

SUMMARY OF THE INVENTION A multimode antenna according to the present invention comprises N wires 1 for generating circularly polarized waves.
Includes a helical type antenna spirally wound around a cylinder 2 that is permeable to electromagnetic waves, and a monopole type antenna 3 provided along the center axis of the helical type antenna, The N wires are each connected to the output of the feeder 5 having one input 6 and N outputs 7 in a form suitable for phase and amplitude.

The diameter D1 of the cylinder, the number N of the wires, the pitch angle A1 of the wires, the length L1 of the wires, the phase and the amplitude are each determined by a radiation pattern of a portable antenna in a satellite communication system. The length LL of the monopole type antenna
1. Each of the load structures 14 is determined by matching the radiation pattern and the monopole type antenna, and the diameter of the wire optimizes the interaction of the monopole type antenna.

Further, the feeder is provided at a lower portion of the cylinder, and the cylinder is supported on an inner diameter side of the cylinder by a cylindrical guide member provided in a communication device housing. Is supported by a support member provided inside the guide member in the communication device housing.

Further, the input section of the feeder is introduced into the communication apparatus casing through a through hole provided outside the cylinder in the communication apparatus casing, and the input section of the monopole type antenna is connected to the input section of the monopole type antenna. The supporting member is introduced into the communication device housing through through holes provided in the communication device housing at corresponding locations.

[0014]

[Function] The resonance frequency of the monopole type antenna is
It is determined by its length and is a quarter wavelength of the desired frequency F1. The feed system and support structure are designed to provide perfect matching and power requirements at frequency F1 in linear polarization to cover terrestrial communications.

Helical type antennas are designed in a completely separate form to cover satellite communications.
It has a set of wires spirally wound around a transparent cylinder and fed with different phases and amplitudes. This is an antenna for satellite communication.

Since the antenna for satellite communication is circularly polarized and symmetric with respect to the central axis, a monopole type antenna can be inserted therein. All effects are matched externally to compensate for small impedance level effects in the feed system. Small changes in the radiation pattern can be improved by optimizing the helical type antenna relative to the monopole type antenna.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIGS. In FIG.
This multi-mode antenna has a helical type antenna in which N wires 1 are spirally wound around a cylinder 2 capable of transmitting electromagnetic waves in order to generate circularly polarized waves. And a monopole type antenna 3 provided along the central axis. Each of the N wires 1 has one input section 6 and N output sections 7
And an output section 7 of the feeder 5 having a phase and an amplitude in an appropriate form.

The diameter D1 of the cylinder 2, the number N of the wires 1,
The pitch angle A1 of the wire 1, the length L1 of the wire 1, the phase and the amplitude are each determined by the radiation pattern of the portable antenna in the satellite communication system.

On the other hand, the length LL1 of the monopole type antenna 3 and the load structure 14 are determined by matching the radiation pattern and the monopole type antenna 3, respectively.

Further, the interaction of the monopole type antenna 3 is optimized by the diameter of the wire 1.

FIG. 2 is a perspective view showing the relationship between the wire 1 and the monopole type antenna 3 in a perspective view, and shows the communication device housing 4 in a cylindrical shape. Are provided in various forms depending on the form of the communication device.

In FIGS. 1 and 3, the feeder 5 is provided below the cylinder 2. The cylinder 2 is supported on the inner diameter side of the cylinder 2 by a cylindrical guide member 41 provided in the communication device housing 4. The monopole type antenna 3 is supported by a support member 42 provided inside the guide member 41 in the communication device housing 4.

The input section 6 connected to the feeder 5 attaches a wiring pattern to the outer wall of the cylinder 2 and connects a lead wire 61 to the wiring pattern. The input section 6 is provided outside the cylinder 2 in the communication device housing 4. Is introduced into the communication device housing 4 through the through hole 43.

On the other hand, the input part of the monopole type antenna 3 is provided with a feeder 8 by a support member 42 and a through-hole 44 provided in a communication device housing 4 at a corresponding position.
(Only the communication device housing 4 side is shown) and is introduced into the communication device housing 4.

FIG. 4 shows the measurement results of the matching performance for the monopole type antenna 3. In this example, four wires 1 are wound once around a cylinder 2 having a diameter of 10 mm of a helical antenna, and the total height is 100 mm. The monopole type antenna 3 has a length of 83 mm.

FIG. 5 shows a measurement result of the monopole type antenna 3 at 950 MHz. Variations were made to elevation and the gain obtained was about 5 dB.

FIG. 6 shows a radiation pattern on an elevation plane when only a helical antenna is used. Here, a gain of 8.5 dB is shown.

FIG. 7 shows a helical type antenna radiation pattern having a monopole type antenna 3 on the inside, which is almost the same as FIG.

[0029]

According to the present invention, it is possible to provide a compact and low-cost multimode antenna suitable for the field of personal communication.

[Brief description of the drawings]

FIG. 1 is an external view showing a multimode antenna according to a preferred embodiment of the present invention.

FIG. 2 is a perspective view showing a relationship between a wire and a monopole type antenna in the multi-mode antenna of FIG. 1 for easy understanding.

FIG. 3 is a cross-sectional view for explaining a support structure of the multi-mode antenna of FIG.

FIG. 4 is a diagram showing a measurement result of a matching performance of the example shown in FIG. 1;

FIG. 5 is a diagram showing measurement results of radiation performance of the example shown in FIG. 1;

FIG. 6 is a diagram showing measurement results of radiation performance of the example shown in FIG. 1;

FIG. 7 is a diagram showing measurement results of radiation performance of the example shown in FIG. 1;

FIG. 8 is a diagram showing a first example of a conventional antenna.

FIG. 9 is a diagram showing a second example of a conventional antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire 2 Cylinder 3, 16 Monopole type antenna 4 Communication device housing 5, 8 Feeder 6 Input part 7 Output part 17 Handy phone 18 Helical antenna 20 PIFA type antenna 41 Guide member 42 Support member

Claims (4)

[Claims] 1. N wires 1 for generating circularly polarized waves
Includes a helical type antenna spirally wound around a cylinder 2 that can transmit electromagnetic waves, and a monopole type antenna 3 provided along the center axis of the helical type antenna, A multi-mode antenna, characterized in that the N wires are each connected to the output of a feeder 5 having one input 6 and N outputs 7 in a suitable manner in terms of phase and amplitude. 2. The multimode antenna according to claim 1, wherein the diameter D1 of the cylinder, the number N of the wires, the pitch angle A1 of the wires, the length L1 of the wires, the phase and the amplitude are each satellite communication. The length LL1 of the monopole type antenna and the load structure 14 are determined by the radiation pattern of the portable antenna in the system, and the load structure 14 is determined by the matching of the radiation pattern and the monopole type antenna, respectively. A multimode antenna characterized in that the interaction of a monopole type antenna is optimized. 3. The multi-mode antenna according to claim 2, wherein the feeder is provided at a lower portion of the cylinder, and the cylinder is supported on an inner diameter side of the cylinder by a cylindrical guide member provided in a communication device housing. Wherein the monopole type antenna is supported by a support member provided inside the guide member in the communication device housing. 4. The multi-mode antenna according to claim 3, wherein the input unit of the feeder is introduced into the communication device housing through a through hole provided outside the cylinder in the communication device housing; A multi-mode antenna, wherein an input part of a pole-type antenna is introduced into the communication device housing through through holes provided in the support member and the communication device housing at corresponding locations.