JP3081103B2 - antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna which functions as a high-gain antenna regardless of whether the antenna is in a retracted state or an extended state.

[0002]

2. Description of the Related Art In recent years, for example, portable radio telephones such as portable radios have been miniaturized so that they can be easily carried, and antennas can be stored in a housing so that they can be easily carried.

When the portable radio is used, the antenna is in an extended state to function as an antenna. However, even when the antenna is in the stowed state when not in use, it can only receive a call signal. A function as an antenna is required.

Therefore, in a conventional antenna of this type, as disclosed in Japanese Patent Application No. 3-245603, a quarter of an antenna is used.
A 1/4 wavelength helical antenna element is placed at the end of the monopole antenna element with a wavelength. When using a portable wireless device, both the monopole antenna element and the helical antenna element are drawn out of the housing and are not used. Sometimes, the monopole antenna element is housed in a housing, and only the helical antenna element is configured to be housed so as to protrude out of the housing.
In the extended state, the end of the monopole antenna element is electrically connected to one feeder provided in the housing. In the retracted state, the connection between the helical antenna element and the monopole antenna element, that is, the helical antenna element is connected. The termination is electrically connected.

[0005]

In the above-mentioned conventional antenna, the combined output impedance of the monopole antenna element and the helical antenna element in the extended state and the output impedance of the helical antenna element in the retracted state are greatly different. In addition, it is impossible to efficiently transmit a signal received in both the extended state and the housed state to a coaxial cable or the like connected to the power supply unit.

If a matching circuit is provided between the feeder and the coaxial cable in order to improve this, matching between two different output impedances is attempted within a range that cannot be sufficiently satisfied with both but can withstand. It is possible. Further, a matching circuit having a complicated circuit configuration may be considered in order to achieve matching for two different output impedances. In any case, it is difficult to efficiently transmit signals in both the extended state and the retracted state of the antenna and to configure the antenna at low cost.

The present invention has been made in view of the circumstances of the related art, and provides an antenna that can efficiently transmit signals in both the extended state and the housed state of the antenna and that does not require a complicated matching circuit. The purpose is to:

[0008]

In order to achieve the above object, an antenna according to the present invention comprises a first antenna element, a second antenna element electrically connected to a tip of the first antenna element, and a second antenna element disposed inside the metal cylinder. The first antenna element is axially housed and extendable in an insulated state, and a power supply sliding contact is provided at the end of the first antenna element, and the power supply sliding contact is slidably contacted and electrically connected. First and second power supply portions are provided at both ends of the metal cylinder in an insulated state, respectively, and the first power supply portion provided at the tip of the metal cylinder is connected to the first and second antennas. It is connected to a transmission coaxial cable via a first matching circuit that matches the combined output impedance of the element, and the second feeder provided at the end of the metal cylinder is connected to the output of the second antenna element. Impey Which are connected to the transmission coaxial cable via a second matching circuit for matching the Nsu.

A 波長 wavelength helical antenna element is electrically connected to and disposed at the tip of the 波長 wavelength monopole antenna element.
The four-wavelength monopole antenna element is axially housed and extendable in an insulated state, and a power supply sliding fitting is provided at the end of the 前 記 wavelength monopole antenna element.
First and second power supply portions to which the power supply sliding contact metal is slidably contacted and electrically connected are provided at both ends of the metal cylinder in an insulated state, respectively, and provided at a tip end of the metal cylinder. First
Through a first matching circuit for matching the almost infinite combined output impedance of the 1/4 wavelength monopole antenna element and the 1/4 wavelength helical antenna element to a transmission coaxial cable of about 50Ω. The second coaxial cable may be connected to the transmission coaxial cable, and the second power supply unit provided at the end of the metal cylinder may be directly connected to the transmission coaxial cable.

The first and second power supply portions are formed of a metal material having holes of the same diameter on the same axis, and the first and second power supply slide fittings have elasticity in a radial direction. The first and second power supply sections are connected by an insulating cylinder, and the metal cylinder is disposed around the outer periphery of the insulating cylinder. You can also.

Further, the first matching circuit may be arranged so as to be close to a first power supply unit provided at a distal end of the metal cylinder.

[0012]

In the extended state of the antenna, the feeding sliding contact at the end of the first antenna element is connected to the first feeding section, and the combined output impedance of the first and second antenna elements is reduced to the first. Matching is performed by a matching circuit. Further, when the antenna is housed, the power supply sliding contact is connected to the second power supply portion, the first antenna element and the metal cylinder form a coaxial structure, and the output impedance of the second antenna element is reduced to the second power. The matching circuit is used for matching.

If a 1/4 wavelength helical antenna element is disposed at the tip of a 1/4 wavelength monopole antenna element and a transmission coaxial cable of approximately 50Ω is used, the 1/4 wavelength The combined output impedance of the monopole antenna element and the １ ／ wavelength helical antenna element is almost infinite, but this is matched by the first matching circuit. In the housed state, the output impedance of the エ レ メ ン ト wavelength helical antenna element is approximately 73Ω, so that even if the helical antenna element is directly connected to the transmission coaxial cable, no large signal reflection occurs.

Further, if the power supply sliding contact metal has elasticity in the radial direction and is slidably contacted with holes of the same diameter in the first and second power supply portions, a structure having elasticity in the power supply portion itself is provided. Compared to,
The structure as a whole is simple and the diameter of the power supply section can be easily reduced.

Further, by disposing the first matching circuit close to the first feeder, unnecessary radiation from a signal path therebetween can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of an antenna according to an embodiment of the present invention in an extended state and an equivalent circuit diagram thereof.
FIG. 3 is a vertical sectional view of the antenna of FIG. 1 in a housed state and an equivalent circuit diagram thereof. FIG. 3 is a diagram showing the frequency to standing wave ratio of the antenna in the state of FIG. FIG. 4 is a diagram showing a frequency to standing wave ratio of the antenna in the state of FIG.

In FIG. 1A and FIG. 2A, a 1/4 wavelength monopole antenna element 10 as a first antenna element has a conductive fitting 1 having a conductive tip.
2 and a １ ／ wavelength helical antenna element 14 as a second antenna element is screwed and fixed to the connection fitting 12. A bobbin 16 made of an insulating material is provided in the coil of the helical antenna element 14.
Is inserted, and the pitch of the helical antenna element 14 is fixed. Further, the connection fitting 12 and the helical antenna element 14 are covered with a fitting member 18 and a cap 20 made of an insulating material.

The monopole antenna element 10
Power supply sliding contact 2 made of an elastic metal material
2 and fixed. The power supply sliding fitting 22 is provided with a slit 24 from the end face opposite to the side on which the monopole antenna element 10 is provided, and is formed to have elasticity in the radial direction. The insulating tube 26 covers the entire intermediate portion of the monopole antenna element 10.

A small hole through which the monopole antenna element 10 covered with the insulating tube 26 can penetrate and a hole 28 having a diameter with which the power supply sliding contact 22 can slide and resiliently are formed from a conductive material coaxially formed. The first power supply unit 30 and the hole 28
A second power supply portion 34 made of a conductive material and having a hole 32 having the same diameter as that of the bottom and formed coaxially is fixed to both ends of the insulating cylinder 36 with the holes 28 and 32 facing each other. This insulating cylinder 36
Is covered with a metal cylinder 38. The first and second power supply units 30, 34 and the metal cylinder 38 are in an insulated state. Here, the power supply sliding fitting 22 includes first and second power supply units 30 and 3.
4 are axially movable in the holes 28 and 32 and the inside of the insulating cylinder 36. In addition, in the state where the power supply sliding contact fitting 22 is inserted into the hole 32 of the second power supply portion 34 and is in sliding contact therewith, the fitting member 1
8 is a concave portion 4 provided on the distal end surface of the first power feeding portion 30.
0.

Further, a band 42 made of a conductive material is fixedly wound around the outer periphery of the first power supply section 30 and the band 4
One end of the second matching circuit 44 is electrically connected to the input terminal of the first matching circuit 44. The output end of the first matching circuit 44 is connected to a transmission coaxial cable 46 of approximately 50Ω. Further, a soldered terminal 48 made of a conductive material is fixed to the second power supply unit 34, one end of a second coaxial cable 50 is soldered thereto, and the other end is connected to the transmission coaxial cable 46. . The outer conductors of the transmission coaxial cable 46 and the second coaxial cable 50 are appropriately grounded, and the metal cylinder 38 is also properly grounded.

Then, a first power supply unit 30 is inserted into an antenna mounting hole (not shown) formed in a housing of the portable wireless device, with the front end flange portion facing outward, and the first power feeding unit 30 is inserted from the inside to the middle portion. A nut is screwed into a male screw engraved on the outer periphery, and the antenna is fixed to the housing.

In this configuration, when the antenna is in the extended state, as shown in FIG. 1, the power supply sliding contact fitting 22 slides on the first power supply portion 30 and the monopole antenna element 10
Is connected to a transmission coaxial cable 46 via a first matching circuit 44. The antenna functions as an antenna in which the に wavelength helical antenna element 14 is stacked on the 波長 wavelength monopole antenna element 10, and its combined output impedance is almost infinite. Therefore, if the first matching circuit 44 is configured as a circuit in which the input impedance is substantially infinite and the output impedance is substantially 50Ω, matching is achieved, and the first matching circuit 44 receives the monopole antenna element 10 and the helical antenna element 14. The signal is transmitted to the transmission coaxial cable 46 efficiently. Note that the first matching circuit 44 may be formed using, for example, a coil or an FET.

In the retracted state of the antenna, as shown in FIG. 2, the power supply sliding contact fitting 22 slides on the second power supply portion 34, and only the helical antenna element 14 protrudes from the housing. And a monopole antenna element 1
0 is accommodated in the metal cylinder 38 to form a coaxial structure. Here, the output impedance of the 波長 wavelength helical antenna element 14 is approximately 73Ω. Then, the signal received by the helical antenna element 14 is transmitted to the transmission coaxial cable 46 via the monopole antenna element 10 having the coaxial structure and the second coaxial cable 50. Since the output impedance of the helical antenna element 14 and the input impedance of the transmission coaxial cable 46 do not differ greatly, signals can be transmitted efficiently even without a matching circuit.

FIG. 3 shows the standing wave ratio in the antenna extended state.
As shown in FIG. 4, the standing wave ratio in the antenna housed state is as shown in FIG.
Signals are transmitted efficiently in a wide band from MHz to 900 MHz. The measurement point of the characteristics in FIGS. 3 and 4 is the input end of the transmission coaxial cable 46.

Another embodiment of the present invention will be described with reference to FIG. FIG. 5 is an equivalent circuit diagram of another embodiment of the antenna of the present invention in the extended state and the housed state. 5, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description will be omitted.

The other embodiment shown in FIG. 5 is different from the embodiment shown in FIGS. 1 to 4 in that a second matching between the second coaxial cable 50 and the transmission coaxial cable 46 is performed. The circuit 52 is interposed, and the connection fitting 12 and the fitting member 18 are formed integrally with a conductive metal.

In such a configuration, in the antenna extended state, it is the same as the embodiment shown in FIGS. Then, in the antenna housed state, the signal received by the helical antenna element 14 is provided to the second matching circuit 52 via the monopole antenna element 10 forming the coaxial structure and the second coaxial cable 50, and matching is performed. And supplied to the transmission coaxial cable 46. Since the output impedance of the 波長 wavelength helical antenna element 14 is approximately 73Ω, the coaxial structure formed by the monopole antenna element 10 and the second coaxial cable 50 are approximately 73Ω, and the second matching circuit 52 is input. The impedance is almost 73Ω and the output impedance is almost 5
If it is 0Ω, the signal can be transmitted more efficiently. Also,
By integrating the connection fitting 12 and the fitting member 18, the number of parts and the number of assembling steps can be reduced and the strength can be increased. In addition, by this integration, in the antenna storage state,
The terminal end of the helical antenna element 14 is electrically connected to the first feeding unit 30, and a received signal is provided to an input terminal of the first matching circuit 44. However, the impedance is greatly different, and the signal is not reflected and input, and can be regarded as substantially not connected.

In the above embodiment, the first antenna element is the monopole antenna element 10 and the second antenna element is the helical antenna element 14. However, the present invention is not limited to these, and the first antenna element is a helical antenna element. And the second antenna element may be a monopole antenna element. The structure of the power supply sliding contact fitting 22 and the first and second power supply portions 30 and 34 is not limited to that of the embodiment, and the first and second power supply portions 30 and 34 have elasticity on the side of the power supply slide. You may make it elastically contact the metal fitting 22. Further, the structure of the insulating cylinder 36 and the metal cylinder 38 is not limited to the embodiment, and a conductive metal film may be provided on the outer periphery of the insulating cylinder 36 and may be used as the metal cylinder 38. 38
An insulating film may be provided on the inner periphery of the first and second power supply portions 30 and 34 by means of a metal cylinder 38 and the both ends may be fixed in an insulated state.

Further, in another embodiment shown in FIG.
The second matching circuit 52 is provided close to the second power supply unit 34, and the output end of the second matching circuit 52 is connected to the transmission coaxial cable 46 via the second coaxial cable 50. good.

In the above embodiment, the helical antenna element 14 has a quarter wavelength.
The effective length may be around four wavelengths. Then, the stacking of the monopole antenna element 10 and the helical antenna element 14 may form an effective length of 波長 wavelength so that the combined output impedance becomes infinite. Further, if the combined output impedance is substantially infinite, no problem occurs in practice, so that the stacking of the monopole antenna element 10 and the helical antenna element 14 may form an effective length of about 波長 wavelength. Furthermore, the effective length of the helical antenna element 14 may be an odd multiple of 1/4 wavelength, and if the effective length of the stack of the monopole antenna element 10 and the helical antenna element 14 is an integral multiple of 1/2 wavelength. good.

[0031]

As described above, since the antenna of the present invention is constituted, the following special effects can be obtained.

In the antenna according to the first aspect, the signal is efficiently transmitted to the transmission coaxial cable regardless of whether the antenna is in the extended state or the housed state, and a higher antenna gain is obtained. In addition, a complicated circuit matching circuit is not required, and the circuit can be configured at low cost.

In the antenna according to the second aspect, a monopole antenna element having a quarter wavelength and a 1 /
By using a helical antenna element of four wavelengths,
In the extended state of the antenna, the first matching circuit is formed according to the almost infinite combined output impedance. In the retracted state of the antenna, the output impedance is substantially 73Ω, and the output impedance of the first matching circuit is approximately 50Ω directly without passing through the second matching circuit. Even if a transmission coaxial cable is connected, there is no large reflection, and the circuit configuration of the entire device becomes simple. Since the second matching circuit is omitted, the configuration can be simplified and the cost can be reduced.

Further, in the antenna according to the third aspect, since the power supply sliding contact metal has elasticity in the radial direction, the first and second power supply portions do not require elasticity, and the first and second power supply portions do not require elasticity. The structure of the power supply unit is simple, which is suitable for miniaturization. In addition, since a slit is provided in the power supply sliding contact fitting having a smaller diameter than the first and second power supply parts to provide elasticity, a slit is provided in the conventional large-diameter power supply part to provide elasticity. It is more durable than elastic.

Further, in the antenna according to the fourth aspect, the signal path from the first feeding section to the first matching circuit is shortened, and unnecessary radiation is reduced accordingly. Therefore,
No special structure for shielding this unnecessary radiation is required.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of an antenna according to an embodiment of the present invention in an extended state, and FIG. 1B is an equivalent circuit diagram thereof.

FIG. 2A is a longitudinal sectional view of the antenna shown in FIG. 1 in a housed state, and FIG. 2B is an equivalent circuit diagram thereof.

FIG. 3 is a diagram showing a frequency to standing wave ratio of the antenna in the state of FIG. 1;

FIG. 4 is a diagram showing a frequency to standing wave ratio of the antenna in the state of FIG. 2;

FIG. 5A is an equivalent circuit diagram of an antenna according to another embodiment of the present invention in an extended state, and FIG. 5B is an equivalent circuit diagram of a stored state.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 monopole antenna element 14 helical antenna element 22 feeding sliding metal fitting 24 slit 28, 32 hole 30 first feeding portion 34 second feeding portion 36 insulating cylinder 38 metal cylinder 44 first matching circuit 46 coaxial for transmission Cable 50 Second coaxial cable 52 Second matching circuit

Claims (4)

(57) [Claims] 1. A second antenna is provided at the tip of a first antenna element.
Are electrically connected to each other, and the first antenna element is axially housed and extendable in an insulated state within the metal cylinder, and a power supply sliding fitting is provided at a terminal end of the first antenna element. And first and second power supply portions to which the power supply sliding contact metal is slidably contacted and electrically connected are provided at both ends of the metal cylinder in an insulated state, respectively, and are provided at the distal end of the metal cylinder. Connected to the first power supply unit.
And a second coaxial cable for transmission via a first matching circuit for matching the combined output impedance of the second antenna element and the second feeder provided at the end of the metal cylinder. An antenna connected to the transmission coaxial cable via a second matching circuit for matching the output impedance of the antenna element. 2. A 波長 wavelength helical antenna element is electrically connected to a tip of a 波長 wavelength monopole antenna element, and the １ ／ wavelength monopole antenna element is disposed in a metal cylinder. A power supply sliding contact is provided at the end of the monopole antenna element having a quarter wavelength, and the power supply sliding contact is slidably contacted and electrically connected to the first one. A second power supply unit is provided at both ends of the metal cylinder in an insulated state, and the first power supply unit provided at a tip of the metal cylinder is connected to the ポ ー ル wavelength monopole antenna element. A 波長 wavelength helical antenna element is connected to the transmission coaxial cable via a first matching circuit for matching an almost infinite combined output impedance of the helical antenna element to a transmission coaxial cable of approximately 50Ω. , Antenna, characterized by being configured to connect to the transmission coaxial cable the second feeding part provided in the end portion of the metallic cylindrical member directly. 3. The antenna according to claim 1, wherein the first and second feeding portions are formed of a metal material having holes of the same diameter on the same axis, and the feeding sliding metal fitting is provided with elasticity in a radial direction. The first and second power supply portions are slidably and elastically connected to the holes of the first and second power supply portions, and the first and second power supply portions are connected by an insulating cylinder. An antenna characterized by comprising a body. 4. The antenna according to claim 1, wherein said first matching circuit is arranged close to a first feeder provided at a tip of said metal cylinder.