JPH06303031A - Diversity antenna mechanism and its configuration method - Google Patents

Abstract

PURPOSE:To reduce considerably the entire length and to facilitate the handling without complicated structure and increase in the manufacture cost by improving the diversity antenna. CONSTITUTION:A sleeve antenna E whose length is lambda/2 and a monopole antenna F whose length is lambda/4 are arranged in parallel concentrically and part of an outer conductor of a coaxial line 11 used for feeding the sleeve antenna acts as the monopole antenna. Moreover, a stub 10 is arranged to the base end of the monopole antenna. Since an unbalanced current is blocked by fitting externally a cylindrical conductor 13 whose electric length is lambda/2 to a coaxial line 12, this method is suitable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism of a diversity antenna used for digital cordless telephones, car telephones, mobile telephones and the like, and to a method of constructing the same, and in particular, it has good radiation characteristics, is small in size and is inexpensive. It is an improved one.

[0002]

2. Description of the Related Art A single antenna such as a whip antenna or a sleeve antenna was used when a vehicle-mounted mobile station or mobile phone entered a practical staircase. After that, the stability of reception was improved. Therefore, a method of receiving diversity on the mobile station side is being put to practical use. Therefore, it is necessary to use two antennas. Thus, it has been proposed to incorporate two antennas into one rod-shaped instrument (for example, Japanese Patent Laid-Open No. 64-78004 / diversity antenna device, hereinafter referred to as a known example). Figure 6
(B) is a schematic cross-sectional view showing a diversity antenna according to a known example. (A) is a schematic cross-sectional view of a diversity antenna according to an embodiment of the present invention, which is shown for comparing dimensions, with the wavelength λ corresponding to the used frequency also shown. In the diversity antenna of the above-mentioned known example (see FIG. 6 (B)), the upper sleeve antenna U and the lower sleeve antenna D are concentrically arranged.
That is, they are arranged in a row so that they share a center line and are located on the extension lines of each other. In the upper sleeve antenna U, an upper radiating element 1 made of a rod-shaped element and a lower radiating element 2 made of a sleeve element are concentrically arranged in a row, and the lower sleeve antenna D is an upper portion made of a rod-shaped element. The radiating element 3 and the lower radiating element 4 composed of a sleeve element are concentrically arranged in a row. Reference numeral 5 is a coaxial power supply line for supplying power to the upper sleeve antenna U, and 6 is a coaxial power supply line for supplying power to the lower sleeve antenna D. According to the above-mentioned publicly known example, it is said that the individual sleeve antennas constituting the antenna mechanism can be put together into one rod-like instrument without degrading the impedance characteristic and the radiation characteristic.

[0003]

SUMMARY OF THE INVENTION In the diversity antenna mechanism according to the known example, a. Since the basic structure of the two sets of sleeve antennas U and D is simply added and arranged in a line without changing the basic form, the vicinity of the center line in the sleeve element which constitutes the lower radiating element 4 of the lower sleeve antenna D In the vicinity (T portion in the figure), the coaxial feed line 5 and the feed means of the lower radiating element 4 have a triple structure, and the connection point to the antenna becomes complicated. The complicated structure not only increases the manufacturing cost but also decreases the reliability. b. The sleeve antenna has a structure in which it is arranged in rows in the upper and lower stages without changing the basic form, and the lower antenna must be electrically separated from the upper antenna to operate. Therefore, the total length of the antenna mechanism is At least 6 times λ / 4 is required (where λ is the wavelength corresponding to the used frequency). For this reason, for example, if an antenna of a base unit (used frequency of 1.9 GHz, λ≈16 cm) of a digital cordless telephone is constructed, the total length becomes 25 to 26 cm, which is inconvenient. For example, since the depth of a cordless telephone for home use is about 20 cm, an antenna longer than this is difficult to use, and is particularly inconvenient for packaging and shipping when shipped from a manufacturing factory. In order to solve such a problem, an example in which the structure can be expanded and contracted is also known, but the structure is further complicated due to expansion and contraction, which makes the operation troublesome and causes a decrease in reliability. The present invention has been made in view of the above circumstances, and has a simple structure, low manufacturing cost, and a total length shorter than the depth (20 cm) of a home-use telephone (1.9 GHz). In the case of the above), and further, it is an object of the present invention to provide a diversity antenna mechanism that is easy to handle and has high reliability, and a method for configuring the diversity antenna mechanism. Further, the present invention is further improved so that the unbalanced current generated in the diversity antenna having the above-mentioned configuration is cut off so as not to cause trouble in the communication device main circuit.

[0004]

In order to achieve the above object (small size, inexpensive and easy to use), an antenna mechanism according to the present invention has a structure in which a sleeve antenna and a monopole antenna are concentrically arranged in a row. In the diversity antenna mechanism, the sleeve antenna is arranged on the tip side and the monopole antenna is arranged on the base side, and the sleeve antenna is provided on the coaxial line for feeding the sleeve antenna. A stub of about λ / 4 is provided at a distance of about λ / 4, a coaxial line for the monopole antenna is connected to an open end of the stub, and the monopole antenna is It is characterized in that it is formed by a part of the outer conductor of the coaxial line for the sleeve antenna. When the above-described configuration according to the present invention is carried out, if a cylindrical conductor having an electrical length λ / 2 is externally fitted to the coaxial line for the monopole antenna, the unbalanced current can be cut off and its adverse effect can be prevented. It is convenient.

The method of the present invention is a method of arranging a sleeve antenna on an extension line of a monopole antenna to form a diversity antenna, wherein the monopole antenna is inside the sleeve element of the sleeve antenna that is anti-resonant at the used frequency. Of the monopole antenna is electrically separated from the sleeve antenna by connecting the base end of the monopole antenna to a stub that is anti-resonant at the used frequency while connecting the tip of the monopole antenna to operate. Is characterized by. By this method, the above-mentioned desired effects (small size, low cost, and ease of use) can be obtained, but in addition, a coaxial conductor of electrical length λ / 2 cannot be fitted on the coaxial line of the monopole antenna. Preventing the balanced current from affecting the communication device main circuit further improves the practical value.

[0006]

According to the above-mentioned means, the diversity antenna having the total size of the sleeve antenna having the length λ / 2, the monopole antenna having the length λ / 4 and the stub having the length λ / 4 is about λ. The antenna is constructed and is significantly shorter (about 2/3) compared to the prior art. Moreover, since a part of the coaxial line for feeding the sleeve antenna on the tip side functions as a monopole antenna, the number of constituent parts is small and the structure is simple.
There is no need for a heavy-duty coaxial line. Since the structure is simple, the manufacturing cost is low and the reliability is high. Since the overall length is basically short, there is no need to make it more telescopic,
Since the expansion / contraction structure does not increase the cost and the expansion / contraction operation is not required, it is easy to use, and there is no fear of causing a failure of the expansion / contraction structure. Furthermore, the unbalanced current that externally fits the λ / 2 cylindrical conductor on the coaxial line is blocked, and the antenna characteristics are stabilized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows one embodiment of a diversity antenna according to the present invention, (A) is a schematic cross-sectional view with a scale of a length dimension added thereto, and (B) is a schematic diagram sharing the above scale. It is a perspective view. As shown in FIG. 1, the schematic configuration of the diversity antenna of the present embodiment has a sleeve antenna E arranged concentrically (on an extension line) on the tip side of the monopole antenna F, and
A stub G is provided on the base end side of the monopole antenna F. Here, the base end side means the feeding coaxial lines 11 and 12
It means the power supply end side. Reference numeral 7 is a radiating element on the tip side of the sleeve antenna E, which is composed of a rod-shaped element, and 8 is a base-side radiating element, which is composed of a sleeve element. /
It is 4. Therefore, their total size is λ / 2.
Coaxial line 11 for feeding the sleeve antenna E
Is inserted into the metal tube 9 by applying an insulating coating to the outer periphery of the outer conductor, the outer conductor is removed at the tip of the coaxial line 11 to expose the core wire, and the core wire is exposed from the tip of the sleeve element 8. The rod-shaped element 7 is formed so as to project by the length dimension λ / 2. When carrying out the present invention, a rod-shaped element (not shown) that is separate from the coaxial line 11 may be configured to connect the core wire of the coaxial line 11 to the rod-shaped element so as to be conductive. The metal tube 9 is integrally connected to and electrically connected to the inner cylinder of the sleeve element 8 having a double cylinder shape. The outer conductor of the coaxial line 11 inserted in the metal tube 9 is connected to and electrically connected to the double tubular sleeve element 8. A stub 10 having a length of λ / 4 is connected to the outer conductor of the coaxial line 11, and the stub 10 and the sleeve antenna E are separated from each other by about λ / 4.
The metal tube 9 is exposed corresponding to the separated portion, and the exposed portion functions as a monopole antenna having a length dimension λ / 4. Reference numeral 12 shown in the figure is a coaxial line for feeding the monopole antenna F, the tip of which is provided with an insulating coating and is inserted into the stub 10, and the core of the coaxial line 12 is of the stub 10. It is connected to the monopole antenna F near the open end and forms a feeding point. The outer conductor of the coaxial line 12 is connected to and electrically connected to the open end of the stub 10 near the feeding point.

FIG. 2A is a schematic diagram equivalently illustrating the diversity antenna of the embodiment shown in FIG. Although the monopole antenna stub 10 and the feed line 12 are connected to the feed line earth side of the sleeve antenna on the tip side formed of the rod-shaped element 7 and the sleeve element 8,
It has nothing to do with the function of the sleeve antenna. Therefore, this sleeve antenna is equivalent to the configuration shown in FIG. SW of this sleeve antenna (main antenna)
The R characteristic is shown in FIG. SW at 1.9 GHz
It can be seen that R is about 1 and has excellent tuneability. When the sleeve antenna side is viewed in the direction of arrow i from the connection point between the monopole antenna and the sleeve antenna, it can be considered that the impedance is infinite. That is, it functions like an electrically separated one.

Further, when the stub 10 of FIG. 2A is viewed in the direction of arrow j, it can be regarded as an electrically separated one because the impedance is extremely large. This is equivalently illustrated in FIG. 2C, where the length dimension λ
It functions as a / 4 monopole antenna and is minimally affected by other components. FIG. 3 (B) is a SWR characteristic chart of this monopole antenna (sub-antenna). The chain line shows the measured value when other constituent parts are removed, and the solid line shows in the embodiment as shown in FIG. It is the measured value when incorporated. It can be seen that the SWR at 1.9 GHz is about 1.6, which shows sufficient practicality.

FIG. 4 shows a modification of the embodiment of FIG. The difference from the embodiment of FIG. 1 is that the coaxial line 1
2, an unbalanced current blocking portion H is formed by externally fitting a tubular conductor 13 having an electrical length of λ / 2 to interrupt the unbalanced current. The unbalanced current described above is a high cycle alternating current, and therefore radiation occurs. Since the coaxial cable 13 is connected to the communication device main body, the unbalanced current adversely affects the communication device main circuit. In addition, the unbalanced current not only deteriorates antenna characteristics, but also causes power loss due to radiation. Furthermore, if the length of the coaxial cable changes, the overall characteristics of the antenna including the cable also change. As a technique for cutting off such an unbalanced current, it is also known to connect a Schwertoff made of a λ / 4 metal tube to an outer conductor of a coaxial cable. However, the conventional technique of connecting the Schwertoff is used in industrial production of an antenna. If you try to apply it in the process, the coaxial cable 13
It is necessary to partially peel off the insulating outer cover to expose the outer conductor, and then fit a Schwertoff made of a metal tube on the outer surface and solder it. Such an operation is very complicated, requires a lot of time and labor, and increases the manufacturing cost. Moreover,
Since the outer conductor of the coaxial cable is heated by the soldering work, there is a restriction that the insulating material in contact with the outer conductor must have heat resistance. Further, there is a problem in that the flexibility that the coaxial cable has is hindered by the Schwertoff, which is a rigid tubular member. Since the location where the schwertoff is provided corresponds to the portion where the coaxial cable 13 is routed inside the case of the communication device main body, it is very inconvenient and difficult to handle if it is stiffened by λ / 4 length. Therefore, in this embodiment, as shown in FIG. 4, the tubular conductor 13 having an electrical length of λ / 2 is fitted onto the coaxial line 13 without being brought into mechanical contact and conduction. Therefore, the work of assembling is good without the need for stripping or soldering the outer cover as in the prior art Schwertoff.

FIG. 5 shows the vicinity of a λ / 2 cylindrical conductor in the above embodiment, (A) is a schematic partial external perspective view for explaining an electrical function, and (B) is a specific structure. It is a perspective view for doing. (A) As shown in the figure, λ / 2
When the base end side is viewed from the front end side (upper side in the figure) of the cylindrical conductor 13, the impedance Z becomes infinite, so that the unbalanced current value I becomes zero. That is, the unbalanced current is blocked. Further, as shown in FIG. 6B, the .lambda. / 2 cylindrical conductor 13 'of this example is constructed by braiding copper wires. With this structure, the λ / 2 cylindrical conductor does not hinder the flexibility of the coaxial cable 1. In carrying out the present invention, the λ / 2 cylindrical conductor 13 does not necessarily have to be a sterically geometrically strict cylinder, and may be a conductive member that cylindrically covers the coaxial cable. Further, in order to easily form the λ / 2 cylindrical conductor, it is preferable to use a braided metal wire as in the above embodiment, but other known flexible materials (for example, conductive composite) Rubber) can also be used.

[0012]

When the present invention is applied, a diver having a total size of about λ including a sleeve antenna having a length of λ / 2, a monopole antenna having a length of λ / 4, and a stub having a length of λ / 4. A city antenna is constructed and is significantly shorter (about 2/3) than the prior art. Moreover, since a part of the coaxial line for feeding the sleeve antenna on the tip side functions as a monopole antenna, the number of components is small, the structure is simple, and the coaxial line has a triple structure as in the prior art. Does not need Since the structure is simple, the manufacturing cost is low and the reliability is high. Since the overall length is basically short, there is no need to make it more telescopic, so there is no increase in costs associated with telescopic structure, no need for telescopic operation, it is easy to use, and there is a risk of failure of the telescopic structure part. It has an excellent practical effect of not having it.

[Brief description of drawings]

FIG. 1 is a diversity antenna 1 according to the present invention.
FIG. 3 is a schematic cross-sectional view showing an embodiment, in which (A) shows a scale of a length dimension, and (B) is a schematic perspective view sharing the above scale.

FIG. 2 is provided to explain the basic principle of the above embodiment, and (A) is an explanatory diagram of the overall configuration,
(B) is an operation explanatory view of the main antenna portion, and (C) is an operation explanatory view of the sub antenna portion.

FIG. 3 is provided to explain the operation and effect in the above embodiment, and (A) is the SW of the main antenna portion.
R characteristic chart, (B) is a SWR characteristic chart of the sub-antenna part.

FIG. 4 shows an example in which the embodiment of FIG. 1 is further improved,
(A) is a cross-sectional view and (B) is a perspective view.

FIG. 5 is an explanatory diagram of the improved example shown in FIG. 4, in which (A)
Is a principle explanatory diagram, and (B) is an explanatory diagram of a specific structure.

FIG. 6B is a schematic sectional view showing a diversity antenna according to a known example. (A) is a schematic cross-sectional view of a diversity antenna according to an embodiment of the present invention, which is shown for comparing dimensions, with the wavelength corresponding to the frequency used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper upper radiating element, 2 ... Upper lower radiating element, 3 ... Lower upper radiating element, 4 ... Lower lower radiating element, 5, 6 ... Coaxial feed line, 7 ... Rod-shaped element of sleeve antenna, 8 ... sleeve of sleeve antenna, 9 ... metal tube acting as monopole antenna, 1
0 ... Stub, 11, 12 ... Coaxial line, 13 ... Cylindrical conductor,
13 '... Cylindrical conductor composed of braided wire.

Claims (12)

[Claims] 1. A diversity antenna mechanism in which a sleeve antenna and a monopole antenna are concentrically arranged in a row, and a sleeve antenna is provided on the distal end side and a monopole antenna is provided on the proximal end side. The coaxial line for supplying power to the sleeve antenna is separated from the sleeve antenna by about λ / 4 and has a length of about λ / 4.
Stub is provided, the coaxial line for the monopole antenna is connected to the open end of the stub, and the monopole antenna is formed by a part of the coaxial line outer conductor for the sleeve antenna. The diversity antenna mechanism, which is characterized in that 2. A coaxial line for feeding power to the sleeve antenna on the tip side is provided with an insulating coating, and the insulating coated coaxial line is housed in a metal tube, and 3. The diversity antenna mechanism according to claim 1, wherein the sleeve element of the tip end side sleeve antenna and (b) the stub of the base end side monopole antenna are connected and electrically connected. 3. A coaxial line for feeding power to the monopole antenna on the base end side is provided with an insulating coating, and an outer conductor of the coaxial line is connected and conducted to the open end of the stub near the feeding point. Claim 1 characterized by the above.
Diversity antenna mechanism described in. 4. The outer conductor for the coaxial line for the sleeve antenna on the tip side is located between the sleeve antenna and the stub and functions as a monopole antenna at about λ /.
The length dimension of the section 4 has a deviation compared with λ / 4, and the length dimension of the stub is set to a length that cancels the reactance of the monopole antenna. The diversity antenna mechanism according to claim 1, which is characterized in that. 5. A cylindrical conductor having an electrical length λ / 2 is externally fitted to the coaxial line for the monopole antenna so as to be positioned closer to the base end than the stub. The diversity antenna mechanism according to claim 1. 6. The cylindrical conductor having an electrical length of λ / 2 is
The diversity antenna mechanism according to claim 5, wherein the diversity antenna mechanism is a braided body made of wire strips of a conductor. 7. A method of arranging a sleeve antenna on an extension line of a monopole antenna to operate a diversity antenna, wherein the tip of the monopole antenna is connected to the inside of the sleeve element of the sleeve antenna that is anti-resonant at the used frequency. And a conductive stub that is anti-resonant at a frequency used, and the base end of the monopole antenna is connected to the stub to electrically operate the monopole antenna from the sleeve antenna. , Diversity antenna configuration method. 8. A coaxial line for supplying power to the sleeve antenna is provided with an insulating coating, the coaxial line is inserted into a metal tube, the metal tube is connected to a sleeve element of the sleeve antenna, and the metal is used. 8. The method of constructing a diversity antenna according to claim 7, wherein the tube is connected to a stub of the monopole antenna so as to be electrically connected. 9. A coaxial line for feeding power to the monopole antenna is provided with an insulating coating, and an outer conductor of the coaxial line is connected to an open end of the stub so as to be conductive in the vicinity of a feeding point of the coaxial line. The diversity antenna configuration method according to claim 7. 10. The wavelength corresponding to the used frequency is λ, the length dimension of the monopole antenna is about λ / 4, and when there is a slight deviation from λ / 4, the stub 8. The diversity antenna configuration method according to claim 7, wherein the reactance component of the monopole antenna is canceled by making the length dimension longer or shorter than λ / 4. 11. An unbalanced current is blocked by connecting a coaxial line for the monopole antenna to an open end of the stub and externally fitting a cylindrical conductor having an electrical length λ / 2 to the coaxial line. The method of constructing a diversity antenna according to claim 7, wherein: 12. The method of constructing a diversity antenna according to claim 7, wherein the tubular conductor having the electrical length λ / 2 is formed of a braided conductor wire.