JP2525151B2 - Telescopic antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a telescopic antenna such as a mobile portable transmitter / receiver device, in which the external configuration of the antenna is formed in a telescope shape by an insulating material such as synthetic resin, Another object of the present invention is to provide a telescopic antenna in which a coiled antenna element is inserted to change the electric length of the antenna within a telescopic range to enable transmission and reception of a plurality of frequency bands over a wide band.

(Prior Art) As a telescopic antenna used in a transmitting / receiving device such as a mobile radio, a television, and a radio, a rod antenna using a metal tube is well known and well known. It is common to use a different diameter metal tube such as so-called brass with a surface treatment such as chrome plating, and to expand and contract by interposing a metallic elastic member between each different diameter tube material when transmitting and receiving a single frequency. When it is not used, it is extended and then reduced and stored in a cabinet or the like.

In addition, the one applied with such a configuration relationship is
There is one using a coiled antenna element as in 20097 or Japanese Utility Model Publication No. 54-19804. The former one is one in which coil-shaped conductors are embedded in each different diameter pipe material of an insulator and is assembled in the same way as a rod antenna, and the latter is used by being protruded from the wireless device by a coil spring in the different diameter pipe material of an insulator. This is a so-called pop-out type antenna. This is due to the elastic force of the coil spring, and the insulating pipe material is simply a spring cover. In addition, the applicant of the present application forms the coiled antenna with a thin metal wire, and uses one having a small elastic action so as to follow the expansion and contraction operation,
The external structure is formed of a different diameter pipe material with an insulating material, and when the different diameter pipe material is assembled, a rotation preventing means in the circumferential direction is formed between a series of pipe materials, and a coil-shaped antenna element made of a thin metal wire is used as a machine. It provides a stable mechanism both physically and electrically.

(Problems to be Solved by the Invention) Any of the antennas using the above-mentioned coiled antenna element is a shortened antenna in which the electrical length is increased in a short size as compared with the rod antenna, but a predetermined single frequency or low It is intended for transmission and reception only for a narrow band that is either high or high, and the coil pitch of the coiled antenna element is set at equal intervals, and it is extended during transmission and reception like a metal rod, If it is not used, it is reduced, and it is difficult to transmit / receive from a low frequency to a high frequency. Especially, it is not possible to achieve preferable reception in a device which receives a wide band from the FM band to the TV band in recent years.

(Means for solving the problem) A plurality of different-diameter pipes that are telescopically assembled so that they can be expanded and contracted are each formed as a molded body made of an insulating material such as synthetic resin. A coil-shaped antenna element is provided in the internal space from the uppermost pipe member to the lowermost pipe member, which is slidable by a joining piece and has means for preventing rotation in the circumferential direction formed between the different diameter pipe members. In a telescopic antenna that is inserted through and fixed at both ends,
The coiled antenna element has a coiled base end side where the coil pitch hardly changes when the spatial element length is reduced to an intermediate state, and a close coiled tip end side where the coil pitch changes preferentially. A telescopic antenna characterized by being formed.

(Function) Not only does the shape and weight be reduced by forming the different-diameter pipe material with an insulating material such as synthetic resin, but also adopts colors that bring about various aesthetics that match the transceiver and the object to be attached. It is also possible, and the one molded with a resin material, which is a new material in recent years, is excellent in flexibility and unlike a metal rod that causes bending damage, it can withstand bending due to a bending effect etc. Since it also has a feature as described above, and it sufficiently acts as a cover for mechanically protecting the coiled antenna element, it is possible to form the antenna element with a thin metal wire. That is, since the antenna element itself does not require a strong elastic force, a metal that does not exhibit a resistance action (elasticity action) that substantially impedes expansion and contraction between pipe members of different diameters. Fine lines are fine. Moreover, in the structure of the coiled element of the present invention, as shown in FIG. 1, the base end side connected to the conductive holder 7 serving as a feeding point is sparsely wound and the tip end side is closely wound. Inserted into the expandable tube with different diameter pipes 1, 2, 3, ... by forming different shapes on both sides, and fixing the close winding end with the top decorative ball 9 etc. By changing the pitch of, the distributed capacitance between windings (hereinafter simply referred to as distributed capacitance) changes with the tip side and the base side different, so the shunt state of the antenna current changes,
Since the substantial electrical length of the antenna varies over a wide range, the antenna can be a telescopic antenna having excellent broadband characteristics.

In addition, when the spatial element length used in the present invention is reduced to an intermediate state, it is formed by a coiled base end side where the coil pitch hardly changes and a close coiled tip side where the coil pitch changes preferentially. It is natural that the coiled antenna element thus obtained can be obtained by quenching the coiled base end side, or by using a coil having a large diameter wire on the coiled base end side. However, even if it is a coil made of wire material of the same material and the same diameter, including hardening, etc., even if one half of the coil that has been bent and formed as a tightly wound portion is stretched into a leap shape, If a compressive force is applied in the length direction of the coil having the winding portion integrally formed, the close winding portion is preferentially compressed and deformed so that the coil pitch is substantially in close contact, that is, a tubular conductor is formed. On the other hand, the coil pitch of the leap winding part hardly changes. Be made as ascertained readily experimentally, the present invention is intended to employ any such coil.

(Embodiment) The electrical action of the coiled antenna element (hereinafter referred to as an antenna element) according to the present invention will be specifically described with reference to the embodiment shown in FIG. 9. W is a metal that is wound into a coil to form an antenna element. The length of the thin wire is shown, A is the spatial element length between P and T of the antenna element which follows the expansion and contraction of the different diameter pipe material, L is the electrical length of the antenna element, and l is the sparse and dense The electrical length of each part of the winding part which changes due to expansion and contraction is shown. C is the distributed capacitance between the coils, I is the maximum value of the current distribution, and P is the feeding point of the high frequency power source.

To explain the operation as an antenna, it is standard to use a doublet antenna that feeds from the center of the element length of λ / 2 as shown in FIG. 10. However, the doublet antenna shown in FIG. It is assumed that one is shown, and the description will be made assuming that the element length of λ / 4 is formed.

At full extension When the spatial element length A ₁ of the antenna element shown in Fig. 9 (a) is extended to the maximum extent by a cover made of a pipe with a different diameter, a coil-like shape is formed between P and T fixed to both ends of the cover. It is formed by the portion W ₁ and the close-wound portion W ₂ . In the case of full extension, W ₂ is sufficiently extended, so that the distributed capacitance between the coils is extremely small, and the relationship of C ₁ ≈C ₂ ≈0 occurs. That is, since the antenna current almost flows through the W ₁ and W ₂ portions, the electrical length is l≈W ₁ , l ₂ ≈W ₁
Therefore, the electrical length of the spatial element length A ₁ is L ₁ (= l ₁ + l ₂ ) ≈W
Since (= W ₁ + W ₂ ), the electrical length L for the resonance wavelength λ
Relationship is λ = 4L, Λ ₁ = 4L ₁ , The relationship is established. In short, the antenna element A ₁ has an electrical length L ₁
It becomes maximum when ≈W, and resonates at the longest wavelength, that is, the lowest frequency. For example, if A ₁ = 60 cm and W = 1 m, then λ
It will resonate at ₁ = 4 m and f ₁ = 75 MHz.

At middle extension The spatial element length A ₂ of the antenna element shown in FIG. 9 (b) is in a state of being further reduced as in the embodiment shown in FIG. ₂ , and the coil-shaped portion at the spatial element length A ₂ The pitch of W ₁ hardly changes and is maintained in the state of l ₃ ≈ W ₁ ≈ l ₁ , but only the coil pitch of the close-wound portion W ₂ is reduced preferentially, and the distributed capacitance of W ₂ is Due to the relationship of C ₄ >> C ₂ , most of the antenna current
Is shunted to C ₄ side not flow almost to W _2, the result W electrical length of ₂ parts l ₄ << l _3, and the thus electric action with respect to the antenna element A ₂ is殆Ndo W Since it is done in only _one part, its electrical length L ₂ is determined by l ₃ , that is, L ₂
<Get the relationship of L ₁ . λ ₂ = 4L ₂ , Therefore, f ₂ > f ₁ and resonance occurs at a frequency higher than f ₁ . For example, if A ₂ = 30 cm and W ₁ = 40 cm, then λ ₂
= 1.6m, and f ₂ = 187.5MHz.

Spatial element length A ₃ of the antenna element shown in full reduction at Figure 9 (c) is a state as is housed all the bottom tube member as in the embodiment shown in FIG. 3, the antenna element A ₃ is At the time of extension, W ₁ and the close-wound portion W ₂ which were the coil-wound portion at the time of intermediate extension are compressed together in this housed state, that is, all the coils W are in a close contact state, and the tubular conductor is Form. That is, since the coil pitches are closely contacted with each other, they are electrically short-circuited and can be regarded as a single pipe state. As a result, L ₃ ≈A ₃ is the shortest. Therefore, we obtain the relation of electric length L ₃ <L ₂ , so λ ₃ = 4L ₃ , Therefore, the relationship of f ₃ > f ₂ is obtained, and the resonance can occur at a frequency higher than f ₂ . For example, if A ₃ = 15 cm, then λ ₃
It resonates at 60 cm and f ₃ = 500 MHz.

From the above explanation, the antenna element that expands and contracts by the pipe with different diameter has a larger rate of change of electrical length L ₁ > L ₂ > L ₃ than the rate of change of spatial element length A ₁ > A ₂ > A _3. Therefore, it is possible to obtain an antenna which is miniaturized and resonates in a wide band frequency, and moreover, the antenna element of the present invention in which the antenna element is formed by the coiled portion and the tightly coiled portion has all resonance frequencies as shown in FIG. This is because the impedance of the feeding point is kept at a normal value even for the band so that the electric action of the antenna is not degraded. In principle, a coiled antenna element having a uniform pitch can be adapted.

What has been described above is performed with an element length of λ / 4, but it is possible to resonate with a desired wavelength other than λ / 4.

A specific embodiment of the present invention as described above will be described with reference to the accompanying drawings. A plurality of different-diameter pipe materials 1, 2, 3, ... In addition, the mechanical constitutional relation itself that can be connected so as not to come out is the same as that of a general telescopic antenna known from the past, but in the present invention, a series of different diameter pipe materials 1, 2, 3, ... Are antennas. It is not used as an element, and therefore has a different essence in that it is generally a synthetic resin molded material. Another coil-shaped antenna element 6 is used, and one end of this coil-shaped antenna element 6 is connected to the above-mentioned series. Of the different-diameter pipe materials 1, 2, 3, ... Are fixed to the upper end decorative ball 9 of the uppermost pipe material 1 and the other end is inserted into the lowermost step 3 into the stepped projection 71 of the conductive holder 7 to form a ring member. Fix each with 8 It is connected to the transceiver device (not shown) via a conductive retainer 7 with stretchable to.

In the coil-shaped antenna element 6 which is inserted in the above-described configuration, the base end side closer to the conductive holder 7 than the boundary portion 6a is a rough winding portion.
61 to form a contact-like portion 62 reaching the tip side, and
Coarse winding 61 and contact winding 62 are shown in Fig. 9 (a) during full extension shown in the figure.
It works as described in. FIG. 2 shows a state of middle extension, which is reduced by one step, but it is the same as that operated to the middle in the expansion / contraction range, and operates as described in FIG. 9 (b). FIG. 3 shows a state in which all the parts are retracted, that is, all are accommodated in the lowermost tube material 3.
The coil, which is 61, forms a close contact like the densely wound portion 62, and both portions 61, 62 form a tubular shape, which has the same effect as described in FIG. 9 (c).

As described above, the coiled antenna element 6 is formed of a thin metal wire against expansion and contraction of the tube members 1, 2, 3, ..., Thus, the expansion and contraction operation is substantially resistant (so-called elastic effect).
Is not shown.

Further, the different-diameter pipe materials 1, 2, 3, ... As described above have a structure for preventing rotation in the circumferential direction, and as shown in FIG. An engaging hole 10 is provided on the lower end side, and a synthetic resin joining piece 11 as shown in FIG. 5 is attached to such a lower end portion. The upper ends of the different-diameter pipe materials 2, 3, ... Other than the uppermost-stage pipe material 1 form a narrowed portion that is bent inward, and the inner surface of the pipe material has an engagement line 2a or
3a is formed, and the engaging strip 2a or 3a is fitted in the gap formed between the both side edges 14 of the joining piece 11. Therefore, the pipes 1 having different diameters 1, 2, 3, ... Assembled by the joining piece 11 do not rotate in the circumferential direction regardless of the expansion and contraction operation, and therefore the coiled antenna element 6 has a constant relationship. To maintain. Further, the different-diameter pipe materials 1, 2, 3, ... Are made of polygonal pipe materials, and by using the joining piece 11 adapted to them, it is possible to carry out without a gap portion of the engaging strips 2a or 3a. Further, it goes without saying that the joining piece 11 member may be made of a synthetic resin material like the pipe material and may be welded or the like.

The coiled antenna element 6 may be fixed to the holder 7 by soldering or the like.

In such a coiled antenna element 6, the element length A is shortened by making the required antenna wire length L into a coil shape, and the element length is considerably shorter than that of the metal tube rod antenna, for example, about 50 to 60%. Even if it has a length, it has a wideband transmission / reception characteristic from a low resonance frequency to a high resonance frequency, so that it is more excellent than a rod antenna.

Since the different-diameter pipe materials 1, 2, 3, ... Are like synthetic resin pipes, they can achieve colors and various patterns that are in harmony with the colors of the applicable transmitter / receiver device or mounting part, and expand and contract. Even if the number of times increases, there is no plating peeling like a metal rod antenna, light weight and excellent flexibility,
The conventional antenna of this type is an antenna that is superior in both mechanical and electrical properties and has an aesthetic appearance.

FIG. 11 shows a comparison between the characteristics when the antenna of the present invention is implemented and the conventional rod antenna, which are actually measured with the same length.

This characteristic table shows that according to the present invention in the FM radio reception band (76 to 90 MHz) and the television reception band (90 to 108 MHz) (170 to 222 MHz) when the resonance frequency is extended to around 90 MHz and when it is expanded to around 190 to 200 MHz. The lengths of the resonance antennas at the time of reduction are actually measured with the same length as the rod antenna (shown by the dotted line). The present invention is excellent in that both VSWR and gain are small in the entire resonance frequency band. In contrast to the characteristics, the rod antenna has a large variation, and the rod length must be changed each time the transmission / reception frequency changes, and the rod length must be long for a lower frequency band. Absent.

(Effects of the Invention) As described above, the present invention can provide a new product in which the image of a conventional telescopic antenna of this type has been greatly reformed.

1) By using a pipe material molded from synthetic resin, it is easy to select the color tone that matches the design and color of the mounting part (transmission / reception device or vehicle body) to be applied, and the shape (round shape, square shape, etc.) can get.

2) It is possible to obtain a mobile and portable antenna that has excellent characteristics of flexibility and light weight and is unlikely to cause breakage accidents.

3) The surface does not change such as plating removal due to repeated expansion and contraction operations, and the surface does not change even after long use.

4) By selecting the expansion / contraction range, the electrical length can be substantially changed, and the transmission / reception range in which the frequency can be arbitrary over the wide band is increased.

Moreover, the invention is industrially effective because it is easy to assemble, can be manufactured at a sufficiently low cost, and has stable and excellent characteristics over a wide band.

[Brief description of drawings]

The drawings show an example of an embodiment of the present invention and an electric action. FIG. 1 is a sectional view showing a state at the time of full extension according to the present invention, and FIG. 2 is a sectional view showing an intermediate extension state. Fig. 3, Fig. 3 is a sectional view showing a full reduction, Fig. 4 to Fig. 8 are constituent member diagrams such as pipe members with different diameters and joint pieces, and Fig. 9 is an explanatory view of electrical action.
FIG. 10 is an impedance characteristic diagram, FIG. 11 is a doublet antenna diagram, and FIG. 12 is a measured comparison characteristic diagram. In the figure, reference numerals 1, 2, and 3 denote different diameter pipes made of synthetic resin, 6 a coiled antenna element, 7 a conductive holder, and 9 a decorative ball.

Claims (1)

(57) [Claims] 1. A plurality of different-diameter pipes, which are telescopically assembled so that they can be expanded and contracted, are each formed as a molded body made of an insulating material such as synthetic resin, and a series of these different-diameter pipe members are slid by resinous joint pieces. A means for preventing rotation in the circumferential direction is formed between the different-diameter pipe members and assembled, and the coil-shaped antenna element is inserted into the internal space from the uppermost pipe member to the lowermost pipe member and both ends are inserted. In the telescopic antenna in which the respective parts are fixed, the coil-shaped antenna element has a coil-shaped base end side in which the coil pitch hardly changes when the spatial element length is reduced to the intermediate state, and the coil pitch has priority. A telescopic antenna, characterized in that it is formed by a closely-wound tip end side that changes with time.