JP2001156528A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional antenna system causes a larger loss rate in an impedance matching circuit when the impedance is low. SOLUTION: Four conductors 2 (2-a to 2-d) each having a length of about 1/4 wavelength and acting like an antenna element are placed on an outer wall face of a cylindrical member 1 and feeding sections 3 placed at a lowermost part of the cylindrical member 1 feed the conductors 2 respectively. The four conductors 2-a to 2-d are placed with the same interval and the same inclined angle and the width of the conductors 2-a to 2-d is selected to be 1/8 of the circumference of the cylindrical member 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device which is a four-wire helical antenna.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, "Resonant Quadrifilar H".
elix Design "(by CC Kilgus, Micro
wave Journal, pp. 49-53, 19
It is a perspective view which shows the conventional antenna device described in December, 1970).

In FIG. 1, reference numeral 101 denotes a first helical antenna having a half-wavelength element, 102 denotes a second helical antenna having a half-wavelength element, 103 denotes a coaxial cable for power supply, and 104 denotes a coaxial cable for power supply. 1/4 wavelength slits formed in the outer conductor of the coaxial cable 103; 105, an impedance matching section provided in the inner conductor of the coaxial cable 103; 106, the first and second helical antennas 101, 102. Power supply point.

Next, the operation will be described. Such a four-wire helical antenna having an element length of about a wavelength generally has a narrow band and low input impedance. When the element length is a quarter wavelength, the impedance is about 5 ohms and the band is about 3%. The terminal impedance of a wireless device to which such an antenna device is connected is about 50 ohms, and impedance matching is performed by an impedance matching unit or the like in order to connect the antenna device.

[0005] In addition to the above, a conventional antenna device having a wide band by providing a parasitic element is disclosed in WO 97/115.
No. 07 and US Pat. No. 5,572,227.

[0006]

Since the conventional antenna device is configured as described above, the impedance of the antenna device is as low as about 5 ohms, the proportion of loss in the impedance matching circuit increases, and the characteristics of the antenna are reduced. There were problems such as deterioration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an antenna device which is a four-wire helical antenna having a high impedance and requiring no impedance matching circuit.

[0008]

In the antenna device according to the present invention, the width of each quarter-wave antenna element is 1/8 of the circumference of the cylinder.

The antenna device according to the present invention has four
The antenna has four branch conductors branched from the quarter-wave antenna element and having different lengths from the quarter-wave antenna element and parallel to the quarter-wave antenna element.

An antenna device according to the present invention includes a quarter-wavelength additional antenna element having one end connected to four quarter-wavelength antenna elements at the top and the other end connected to ground. .

The antenna device according to the present invention has four
The diameter of the uppermost side of the cylinder provided with the 波長 wavelength antenna element is larger than the diameter of the lowermost side.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a perspective view showing an antenna device according to Embodiment 1 of the present invention, and FIG. 2 is a developed view showing the antenna device according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a cylindrical member (cylinder), and 2 (2-a to 2-d) are provided on the outer wall surface of the cylindrical member 1 and have four lengths of about 1/4 wavelength. Conductor (1 /
A four-wavelength antenna element); and 3, a power supply unit provided at the bottom of the cylindrical member 1 and supplying power to each conductor 2. As shown in FIG. 2, the four conductors 2-a to 2-d are arranged at the same interval and at the same inclination angle, and the width of each of the conductors 2-a to 2-d is one of the circumference of the circumferential member 1. / 8.

Next, the operation will be described. As shown in FIG. 2, on the cylindrical surface, the conductor 2 as an antenna element and the gap between the conductors 2 have the same shape and the same area. Even if both are replaced, the same configuration is obtained. This antenna device functions as a constant impedance antenna.

As described above, according to the first embodiment, the width of each of the conductors 2-a to 2-d, which are antenna elements, is set to 1/8 of the circumference of the cylindrical member 1. The impedance becomes high based on the shape and arrangement of the antenna element, and the effect of widening the band is obtained.

Embodiment 2 FIG. 3 is a perspective view illustrating an antenna device according to a second embodiment of the present invention, and FIG. 4 is a developed view illustrating the antenna device according to the second embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a cylindrical member (cylindrical); 3, a power supply portion provided at the lowermost portion of the cylindrical member 1 for supplying power to each conductor 4; Four conductors (１ ／ wavelength antenna elements) provided on the outer wall surface of the cylindrical member 1 and having a length of about ４ wavelength,
-A to 5-d) are branched from the four conductors 4-a to 4-d, respectively, and have different lengths from the conductors 4-a to 4-d and are parallel to the conductors 4-a to 4-d. There are four branch conductors.

As shown in FIG. 4, four conductors 4-a to 4-a
-D are arranged at the same interval and at the same inclination angle, and the branch conductor 5-a
5-d are parallel to the conductors 4-a-4-d, have slightly different lengths, and are connected to the conductors 4-a-4-d in the vicinity of the power supply unit 3, respectively.

Next, the operation will be described. One conductor 4
Focusing on −a, the conductor 4-a has a frequency f1 (= 1 / λ1 = 1) whose length L1 is １ ／ of the wavelength λ1.
Resonates at 1 / (4 × L1)). The conductor 4-a
The length L2 of the branch conductor 5-a branched from the
Frequency f2 (= 1 / λ2 = 1 /
(4 × L2)).

Since these conductors 4-a to 4-d and branch conductors 5-a to 5-d are connected to each other,
The antenna has two resonance characteristics.

As described above, according to the second embodiment, each of the four conductors 4-a to 4-d, which are antenna elements, branches off and has a different length from the conductors 4-a to 4-d. And four branch conductors 5- parallel to the conductors 4-a to 4-d.
Since a to 5-d is provided, high impedance is obtained based on the shapes and arrangements of the four antenna elements to which the branch conductors are connected, and an effect of widening the band is obtained.

Embodiment 3 FIG. FIG. 5 is a perspective perspective view showing an antenna device according to Embodiment 3 of the present invention. In the figure, 1 is a cylindrical member (cylinder), 6 is a cylindrical member 1
4 having a length of about 1/4 wavelength
A conductor (1/4 wavelength antenna element) which is the antenna element of the present invention, and 3 is a power supply unit provided at the bottom of the cylindrical member 1 and supplying power to each conductor 6. 7 is connected to the conductor 6 at the uppermost portion of the cylindrical member 1, provided on the inner surface of the cylindrical member 1 in parallel with the conductor 6, and connected to an additional conductor (1/4
Wavelength additional antenna element). 8 is a ground for the feeding point 3.

Next, the operation will be described. Additional conductor 7 connected to conductor 6 at the top of cylindrical member 1 and parallel to conductor 6
Is connected to the ground 8, the antenna device has a folded monopole antenna structure, and the impedance is larger than that of a monopole antenna having the same equivalent radius.

As described above, according to the third embodiment, the additional conductor 7 connected to the conductor 6 at the uppermost portion of the cylindrical member 1 and connected in parallel to the conductor 6 is connected to the ground 8. Based on the shape and arrangement of the four antenna elements of the monopole antenna structure, the impedance becomes high and the effect of widening the band is obtained.

Embodiment 4 FIG. 6 is a perspective perspective view showing an antenna device according to Embodiment 4 of the present invention. In the figure, reference numeral 9 denotes a cylindrical member (cylinder) whose diameter gradually increases from the lowermost portion to the uppermost portion.
4 conductors (1/4 wavelength antenna elements) having a length of 4 wavelengths, and 3 is a 4 conductor provided at the bottom of the cylindrical member 9.
This is a power supply unit of the conductor 10.

Next, the operation will be described. In a four-wire helical antenna, the smaller the antenna diameter, the lower the impedance and the narrower the band. Therefore, as shown in FIG. 6, the impedance is increased by arranging the four conductors 10 at the same interval and the same inclination angle on the outer wall surface of the cylindrical member 9 whose diameter gradually increases from the lowermost part to the uppermost part. .

As described above, according to the fourth embodiment, the diameter of the uppermost side of the cylindrical member 9 provided with the conductors 10 as the four antenna elements is made larger than the diameter of the lowermost side. The impedance becomes high based on the shape and arrangement of the book antenna element, and the effect of widening the band is obtained.

[0028]

As described above, according to the present invention, each 1
Since the width of the 波長 wavelength antenna element is set to be ８ of the circumference of the cylinder, there is an effect that the impedance becomes high based on the shape and arrangement of the four antenna elements, and the band becomes wide.

According to the present invention, there are provided four branch conductors branched from the four quarter-wave antenna elements and having different lengths from the quarter-wave antenna elements and parallel to the quarter-wave antenna elements. As a result, there is an effect that the impedance becomes high based on the shape and arrangement of the four antenna elements, and the band becomes wide.

According to the present invention, since one end is connected to each of the four quarter-wavelength antenna elements at the uppermost part and the other end is connected to the ground, a quarter-wavelength additional antenna element is provided. There is an effect that the impedance becomes high based on the shape and arrangement of the four antenna elements and the band becomes wide.

According to the present invention, the diameter of the uppermost side of the cylinder provided with the four quarter-wavelength antenna elements is made larger than the diameter of the lowermost side. This has the effect of providing high impedance and wide band.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an antenna device according to a first embodiment of the present invention.

FIG. 2 is a developed view showing the antenna device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing an antenna device according to a second embodiment of the present invention.

FIG. 4 is a developed view showing an antenna device according to a second embodiment of the present invention.

FIG. 5 is a perspective perspective view showing an antenna device according to a third embodiment of the present invention.

FIG. 6 is a perspective perspective view showing an antenna device according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional antenna device.

[Explanation of symbols]

1,9 cylindrical member (cylindrical), 2,2a-2d, 4,4a
~ 4d, 6,10 conductor (1/4 wavelength antenna element),
3 feeding point, 5, 5a to 5d branch conductor, 7 additional conductor (1/4 wavelength additional antenna element), 8 ground.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shigeru Makino 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 5J021 AA04 AA08 AA11 AB03 FA31 HA05 HA10 JA02 5J046 AA04 AB07 PA03

Claims (4)

[Claims] 1. An antenna device having four quarter-wavelength antenna elements arranged at equal intervals and at the same inclination angle on a cylindrical surface and having a feed point at the bottom, wherein each quarter-wavelength antenna element Is 1 / the circumference of the cylinder
8. The antenna device as set forth in claim 8. 2. An antenna device having four quarter-wavelength antenna elements arranged at equal intervals and at the same inclination angle on a cylindrical surface, and having a feed point at the lowermost part, wherein: An antenna device, comprising: four branch conductors each branching from a wavelength antenna element and having a length different from that of the quarter wavelength antenna element and parallel to the quarter wavelength antenna element. 3. An antenna device having four quarter-wavelength antenna elements arranged at equal intervals and at the same inclination angle on a cylindrical surface, and having a feed point at the lowermost part, wherein one end is the uppermost part and An antenna device comprising: a quarter-wavelength additional antenna element connected to one of the quarter-wavelength antenna elements and the other end connected to the ground. 4. An antenna device having four quarter-wavelength antenna elements arranged at equal intervals and at the same inclination angle on a cylindrical surface, and having a feeding point at a lowermost part, wherein an uppermost side of the cylindrical part is provided. An antenna device having a diameter larger than a diameter of a lowermost side.