JP2001292020A - Antenna unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna unit where an antenna element (2) can easily be formed with a mount metallic fixture (3) and the electric characteristic of the antenna element (2) is unchanged with a forming pressure at integral forming. SOLUTION: The antenna element (2) and the mount metallic fixture (3) are integrally cast by a casting mold and the antenna element (2) is resonated with an operating band frequency (f) of a mobile communication unit as a 1/4 wavelength ground antenna. No processing process is required for the antenna element (2), and the antenna element (2) is formed at the same time when the mount metallic fixture (3) is formed. Since the antenna element (2) is cast by the casting mold, the antenna element (2) is hardly deformed and the electric characteristic is unchanged due to the shape change in the integral forming process or the covering assembling process, where the antenna element (2) is covered by an insulation cover (5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates to an antenna unit provided in a mobile communication device such as a portable telephone and a PHS, and more particularly to an antenna unit in which an antenna element is covered with an insulating cover.

[0003]

[Prior art]

In recent years, helical antennas having a helical antenna element as an antenna have broadband characteristics and are suitable for miniaturization, and are therefore widely used in mobile communication devices such as mobile phones.

The antenna element is mounted so as to protrude from the housings of these devices. The periphery of the antenna element is made of polyester or synthetic material so that the antenna element is not inadvertently touched and injured, and the antenna element is not deformed by external force. It is covered with an insulating cover made of a material having a relatively small longitudinal modulus such as rubber.

FIGS. 10 (a) to 10 (c) show a method of forming a conventional antenna unit 100 in which the periphery of an antenna element is covered with an integrally formed insulating cover 104. FIG.

The molding method will be described with reference to these drawings. In the drawings, reference numeral 101 denotes an antenna element serving as a helical antenna formed by spirally winding a conductor, and a mounting bracket 102 is fixed to a base end thereof. . The antenna element 101 attaches the mounting bracket 102 to a housing of a mobile communication device such as a mobile phone, and electrically connects an antenna coupling circuit, a transmission / reception circuit, and the like in the communication device via the mounting bracket 102 and a power supply line (not shown). Connect.

The winding pitch P of the antenna element 101
Is set to the pitch determined from the resonance frequency of the helical antenna, and has substantially the same pitch in each portion along the winding axis.

An antenna unit 1 in which the periphery of the antenna element 101 is covered by an integrally formed insulating cover 104
In the molding method 00, first, the spiral antenna element 101 is integrally molded with the primary molding resin, and after the primary molding resin is cured, as shown in FIG. As shown in FIG. 3C, an insulating cover 104 is provided around the antenna element 101 as shown in FIG.
Is integrally formed by secondary molding.

[0010] The antenna element 101 is integrally molded with the primary molding resin only by covering the antenna element 101 with a soft insulating cover 104 such as synthetic rubber.
However, there is a possibility that the resonance frequency may change due to deformation due to an external force, and the deformation is prevented by integrating a hard primary molding resin having a relatively large longitudinal elastic coefficient.

[0011]

[Problems to be solved by the invention]

However, in this conventional molding method,
When the primary molding resin is injected into the mold, the winding pitch P of the antenna element 101 is shifted from P ′ by the molding pressure, and the coil is hardened while being shifted, so that the electric characteristics are different from the set values. occured. As a result, the resonance frequency of the antenna element 101 differs from the design value for each molding depending on the molding conditions, which has caused a decrease in yield in mass production.

Also, the formation of the spiral antenna element 101 at the winding pitch P requires a processing accuracy and a complicated press molding process, and is expensive.

Further, in order to mount the spiral antenna element to the mounting bracket, a spiral groove must be formed in the mounting bracket or a soldering step is required, and the mounting requires an extra step. Was.

The present invention has been made in view of such a conventional problem, and the antenna element can be easily formed together with the mounting bracket, and the electric characteristics of the antenna element can be reduced by the molding pressure at the time of integral molding. Provide an antenna unit that does not change.

[0016]

[Means for Solving the Problems]

The antenna unit according to the first aspect is mounted on a mobile communication device, and is electrically connected to an antenna coupling circuit in the mobile communication device. An antenna element linearly extended from the mounting device is provided. In an antenna unit having an insulating cover for covering an outer periphery of the antenna element, the antenna element and a mounting bracket are integrally molded by injecting a conductive metal material to be melted into a mold under pressure, and the antenna element is formed to have a quarter wavelength. Is characterized in that it is shaped so as to resonate with the operating band frequency f of the mobile communication device.

Since the antenna element and the mounting bracket are integrally cast with a mold, there is no need to process the antenna element, and the antenna element and the mounting bracket can be formed simultaneously with the mounting bracket.

Further, since the antenna element is cast in a mold, the antenna element is not easily deformed, and the electrical characteristics do not change due to a change in shape in an integral molding step for covering with an insulating cover or an assembling step for covering.

Further, since the antenna element is cast with a mold, it can be formed into various shapes in accordance with electrical characteristics such as directivity and resonance frequency required for an antenna of a mobile communication device.

The antenna unit according to a second aspect of the present invention is characterized in that a male screw which is screwed into a female screw of a power supply fitting of the mobile communication device is formed on an outer peripheral surface of the mounting fitting.

Since the power supply fitting and the mounting fitting are screwed together,
Simply by rotating the mounting bracket, it can be mounted on the mobile communication device and electrically connected to the power supply bracket.

According to a third aspect of the present invention, in the antenna unit, the mounting bracket is a plug pin which comes into contact with a center contact of the female coaxial connector mounted on the mobile communication device, and a ring-shaped portion is formed on a portion of the insulating cover which is concentric with the plug pin. It is characterized in that a grounding metal is attached and fitted and connected to a female coaxial connector.

Since the antenna unit is fitted and connected to the female coaxial connector, the antenna unit can be easily attached to the mobile communication device.

Further, when the feed line of the coaxial cable is connected to the female coaxial connector, the antenna unit can be connected while matching the impedance of the feed line.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an antenna unit 1 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an antenna unit 1 without an insulating cover 5.
2A is a plan view of the antenna unit 1 excluding the insulating cover 5, FIG. 2B is a front view of the antenna unit 1, and FIG.
FIG. FIG. 3A is a cross-sectional view illustrating a process of integrally forming the insulating cover 5, and FIG. 3B is a cross-sectional view of the antenna unit 1.

The antenna element 2 and the mounting bracket 3 of the antenna unit according to the present invention are die casts in which a molten conductive metal material is injected under pressure into a mold, cured, taken out of the mold, and integrally formed. .

In the first embodiment, as shown in FIGS. 1 and 2, the antenna element 2 is cylindrical, and the mounting bracket 3 is attached to one end of the cylindrical antenna element 2 along the longitudinal direction. It is formed in a continuous strip shape.

As the conductive metal material, for example, a metal material such as an aluminum alloy or a zinc alloy suitable for casting is used.

The antenna element 2 resonates as a quarter-wavelength ground antenna when the base side (the mounting bracket side) is grounded. It is set according to the use band of the device, and for example, if it is used in a band of 2 GHz, it is formed to be about 3.75 cm, which is λ / 4 of 2 GHz.

Further, since the antenna element 2 has a cylindrical shape, the antenna element 2 is non-directional and resonates in a wide band in the vicinity of 2 GHz which is the frequency band used by the mobile communication device, as compared with the helical antenna element. Therefore,
Even if the transmission frequency and the reception frequency of the communication device are different, 1
Only by using the antenna unit 1, good two-way communication is possible.

As shown in the figure, the mounting bracket 3 is integrally provided in the longitudinal direction of the antenna element 2, and a circular mounting hole 4 for mounting the antenna element 2 on a circuit board is formed in the middle. . The mounting hole 4 may be formed simultaneously with the casting or may be formed after the casting.

In order to integrally form the insulating cover 5 around the antenna element 2, as shown in FIG. 3 (a), the base is sandwiched between upper and lower molding dies 9a and 9b to form a cylindrical antenna. The element 2 is supported in the cylindrical cavity of the molding die 9 with a gap between the inner surface of the molding die 9 and the thickness of the insulating cover 5.

Into the cavity, a thermoplastic insulating synthetic resin such as a polyester elastomer, which becomes the insulating cover 5, is heated and melted and injected. When this molding resin cures, as shown in FIG. 3 (b), a cylindrical insulating cover 5 is formed, the base of which protrudes from one end thereof, and the antenna element 2 is integrally formed in a state where the periphery is covered with a uniform thickness. Embedded in the insulating cover 5.

In the antenna unit 1 thus formed, the mounting bracket 3 is superimposed on a surface of a circuit board (not shown) positioned and accommodated in the housing of the mobile communication device, and the mounting bracket 3 and the circuit board are mounted. The antenna unit 1 is attached to the communication device by tightening each other with a fixing screw through which the antenna unit 1 is inserted. By this mounting, the mounting bracket 3 is connected to the conductive pattern on the circuit board, and is connected to a high-frequency circuit component (not shown) that constitutes a transmitting / receiving circuit of a mobile communication device, an antenna coupling circuit, and the like mounted on the circuit board. Make an electrical connection.

In the antenna unit 1 in which the mounting bracket 3 is fixed to the circuit board, the portion of the antenna element 2 covered by the insulating cover 5 projects from the housing of the mobile communication device.

According to this embodiment, since the antenna element 2 is covered with the integrally formed insulating cover 5 and is not exposed to the outside as it is, there is no danger of injury.

Further, since the antenna element 2 has a cylindrical shape that is hardly deformed, the antenna element 2 is not deformed by the molding pressure in the process of integrally forming the insulating cover 5, and its electric characteristics such as resonance frequency. Does not become unstable depending on molding conditions.

Furthermore, in the manufacturing process of the antenna element 2 and the mounting bracket 3, since both wires can be formed integrally using a mold without bending the wire material for manufacturing a loading coil, the antenna unit 1 can be mass-produced at low cost. it can.

FIG. 4 shows an antenna unit 10 in which the inside of the antenna element 2 is made hollow to reduce the weight of the antenna unit 1 according to the first embodiment.
The antenna unit 10 according to the second embodiment is
The manufacturing process will be described with reference to FIGS. In the second embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

The antenna element 2 and the mounting bracket 3 of the antenna unit 10 according to the second embodiment
This is the same as the embodiment, and differs from the above-described antenna unit 1 in that the insulating cover 11 covers only the periphery of the antenna element 2.

For this reason, in the step of integrally molding the insulating cover 11, the core pin 12a of the molding die 12 is inserted into the antenna element 2, but in order to easily remove the core pin 12a after molding, FIG. As shown in a), before molding, the insulating tube 14 is inserted into the cylindrical antenna element 2 in advance.

The antenna element 2 is supported in the cavity of the molding die 12 with the thickness of the insulating cover 11 therebetween while the insulating tube 14 is inserted therein.
As shown in FIG. 4B, the core pin 12a of the mold 12 is inserted into the insulating tube 14.

After the antenna element 2 is supported in the cavity, a molding resin such as a polyester elastomer which becomes the insulating cover 11 is heated and melted, and injected into the cavity through a gate opening (not shown) of the molding die 12. The molten molding resin flows between the antenna element 2 and the inner surface of the mold 12, and when cured, the antenna element 2 and the molding resin are integrally molded. Then, the core pin 12a
Is pulled out, the cylindrical antenna unit 10 in which only the periphery of the antenna element 2 is integrally covered with the insulating cover 11
Is obtained.

As described above, the antenna unit 10 according to the second embodiment is different from the first embodiment in that the resin serving as the insulating cover 11 does not flow into the antenna element 2, so that the weight of the antenna unit 10 is reduced. Becomes

In the above-described embodiment, an example in which the insulating cover 11 is integrally formed with the antenna element 2 has been described. However, for example, a separately formed hollow insulating cover is placed over the antenna element 2 to cover the same. 3 or the antenna element 2 may be fixed using an adhesive or the like. Even in the work process of putting on this insulating cover,
Since the antenna element 2 has a structure that is not easily deformed,
The electrical characteristics do not vary due to the process of assembling the insulating cover.

FIG. 5 shows an antenna element 21 and a mounting bracket 22 of an antenna unit 20 according to a third embodiment. A cylindrical antenna element 21 has a cylindrical shape with an external thread 22a formed on the outer peripheral surface at one end. The mounting bracket 22 of FIG. Flange 22b and male screw 22a formed on mounting bracket 22
Are formed at the same time when the mounting bracket 22 is cast together with the antenna element 21, so that the cutting of the flange portion 22b and the thread cutting step of the external thread 22a are not required.

In the antenna unit 20, the outer periphery of the antenna element 21 is covered with the insulating cover 23 by any of the above-described methods, and the power supply is fixed to the housing 24 of the mobile communication device A as shown in FIG. It is attached to the fitting 25. That is, a female screw that is screwed into the male screw 22a of the mounting bracket 22 is formed on the inner surface of the insertion hole of the power supply bracket 25. Is fixed to the mobile communication device A. The power supply fitting 25 is connected to a power supply line 26 provided in the device A, whereby the antenna element 21 is connected to the power supply line 26.

According to the third embodiment, the male screw 22a is formed in the mounting bracket 22 at the time of casting.
Simply by rotating, it can be fixed to the mobile communication device A and electrically connected to the power supply line 26.

FIGS. 7 and 8 show an antenna unit 30 according to a fourth embodiment of the present invention. The antenna unit 30 is provided at one end of a cylindrical antenna element 31 with a center contact of a female coaxial connector 40. Die casting is used in which plug pins 32 that come into contact with 41 are integrally connected.

As shown in FIG. 7B, the outer periphery of the antenna element 31 is covered with an insulating cover 33, and a ring-shaped grounding fitting 34 is attached to the insulating cover 33. The earth metal fitting 34 surrounds the periphery of the plug pin 32,
It is attached to the base end side (right end side in the figure) of the insulating cover 33 which is concentric with the plug pin 32, and its outer diameter is a length that fits into the outer conductor 42 of the female coaxial connector 40.

By forming the antenna unit 30 in this way, the antenna unit 30 is fitted and connected to the female coaxial connector 40 fixed to the housing 43 of the mobile communication device as shown in FIG. That is, the antenna unit 30 is attached to the mobile communication device in an upright state only by fitting the base end of the antenna unit 30 to the female coaxial connector 40, and the plug pin 32 and the earth metal fitting 34 are respectively connected to the female coaxial connector 40. Center contact 41 and outer conductor 4
2 electrically. Accordingly, by connecting the center conductor of the feed line 44 formed of a coaxial cable to the center contact 41 and the braided wire to the outer conductor 42, impedance and
By matching, the plug pin 32 connected to the antenna element 31 can be connected to the feed line 44 without transmission loss.

In each of the above embodiments, the shape of the antenna element is all cylindrical, but the shape of the antenna element depends on the shape of the mold used for casting. , And can meet various demands for antennas of mobile communication devices, such as directivity and frequency characteristics.

[0054]

As described above, according to the first aspect of the present invention, since the antenna element and the mounting bracket are integrally formed by casting, the respective forming steps are greatly simplified.

Further, since the antenna element is a die-cast which is hardly deformed by an external force, the antenna element is not deformed in the step of covering the insulating cover and its electric characteristics are not changed, so that the yield of manufacturing the antenna unit can be improved. it can.

Also, since the antenna element is cast with a mold, it can be formed into various shapes in accordance with electrical characteristics such as directivity and resonance frequency required for an antenna of a mobile communication device.

Further, according to the second aspect of the present invention, in addition to this, the antenna unit can be attached to the mobile communication device by simply rotating the antenna unit, and the antenna element can be electrically connected to the power supply fitting.

Further, according to the invention of claim 3, according to claim 1
In addition to the invention, the antenna unit can be easily attached to the mobile communication device only by fitting and connecting to the female coaxial connector.

If the feed line of the coaxial cable is connected to the female coaxial connector, the antenna unit and the feed line can be connected with no transmission loss.

[0060]

[Brief description of the drawings]

FIG. 1 is a perspective view of an antenna unit 1 according to a first embodiment of the present invention, from which an insulating cover 5 has been removed.

2A is a plan view of the antenna unit 1 excluding an insulating cover 5, FIG. 2B is a front view thereof, and FIG. 2C is a side view thereof.

3A is a cross-sectional view showing a step of integrally forming the insulating cover 5, FIG. 3B is a cross-sectional view of the antenna unit 1, FIG.
It is.

4A and 4B show an antenna unit 10 according to a second embodiment of the present invention, and FIG. 4A is a front view showing a state in which an insulating tube 14 is inserted into an antenna element 2 integrated with a mounting bracket 3; FIG. 2B is a cross-sectional view illustrating a step of integrally forming the insulating cover 11, and FIG.
FIG.

FIG. 5 is a front view of an antenna unit 20 according to a third embodiment excluding an insulating cover 23;

FIG. 6 is a longitudinal sectional view showing an attached state of the antenna unit 20.

FIG. 7 shows an antenna unit 30 according to a fourth embodiment of the present invention, wherein (a) is a perspective view of an antenna element 31 and a mounting bracket 32 without an insulating cover 33;
(B) is a perspective view of the antenna unit 30.

FIG. 8 is a longitudinal sectional view showing an attached state of the antenna unit 30.

FIG. 9 shows an antenna element 50 according to another embodiment.
FIG.

10A and 10B show a conventional method of forming the antenna unit 100, FIG. 10A is a front view showing a spiral antenna element 101 and a mounting bracket 102 before molding, and FIG.
FIG. 4C is a longitudinal sectional view of the antenna element 101 and the mounting bracket 102 after the primary molding, and FIG. 4C is a sectional view of the antenna unit 100 in which the insulating cover 104 is integrally molded by secondary molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna unit 2 Antenna element 3 Mounting bracket 5 Insulating cover 22 Mounting bracket 22a Male screw 25 Power supply bracket 32 Plug pin (mounting bracket) 33 Insulation cover 34 Grounding bracket 40 Female coaxial connector 41 Center contact A Mobile communication equipment

Claims (3)

[Claims] 1. A mounting bracket (3) attached to a mobile communication device and electrically connected to an antenna coupling circuit in the mobile communication device, and an antenna element (2) linearly extended and arranged on the mounting bracket (3). ) And an insulating cover (5) covering the outer periphery of the antenna element (2), wherein the antenna element (2) and the mounting bracket (3) are press-injected with a conductive metal material to be melted into a mold. An antenna unit characterized in that the antenna element (2) is shaped as a quarter-wave ground antenna so as to resonate with the operating band frequency f of the mobile communication device. 2. An antenna according to claim 1, wherein a male screw (22a) screwed to a female screw of a power supply fitting (25) of the mobile communication device A is formed on an outer peripheral surface of the mounting fitting (22). unit. 3. The mounting bracket is a plug pin (32) that comes into contact with a center contact (41) of a female coaxial connector (40) mounted on a mobile communication device, and is insulated concentrically with the plug pin (32). 2. The antenna unit according to claim 1, wherein a ring-shaped earth metal fitting is attached to a portion of the cover, and is fitted and connected to the female coaxial connector.