JPH0521536U - Wristwatch receiver - Google Patents

Abstract

(57) [Summary] [Purpose] High sensitivity can be obtained even when wearing and removing the wrist even in the VHF band. [Construction] A receiver is mounted on a board 12 in a case 11, one end of a conducting wire 21 is connected to a feeding point 13 thereof, the conducting wire 21 is arranged along an inner peripheral surface of the case 11, and is attached to a metal back cover 19. The height is 0.005λ (where λ is the wavelength used), the length of the conductor 21 is 0.12λ, and the other end is connected to the back cover 19. Bands 15 on both sides of the case 11,
Helical antennas 26 and 27 extending in the longitudinal direction are respectively held by 16, and one end of the helical antenna 26 is connected to the common potential point 14 of the receiver, and one end of the helical antenna 27 is connected to the back cover 19. The cross-sectional areas of the helical antennas 26 and 27 are 0.02λ × 0.002λ,
The pitch is 0.004λ, the wire diameter is 0.0005λ, and the number of turns is 11. Helical antennas 26, 27, back cover 1
9 and the conductor 21 resonate with λ in free space.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention mainly relates to a wristwatch type receiver which is wound around an arm of a human body and used for portable use, and particularly relates to an antenna structure thereof.

[0002]

[Prior Art]

 Conventionally, as an antenna of a wristwatch type receiver that is worn around a wrist and used as a mobile phone, Japanese Unexamined Patent Publication No. Sho 61-181203 has a wristwatch body (case) having a built-in radio device and an antenna embedded in the band. Has been done. In this antenna, a metal wire extends from the main body along the longitudinal direction of the band, and at the free end of the band, alternately passes through a plurality of small holes for connecting the pair of bands to each other in opposite directions. Thus, the metal wire is formed in a zigzag manner. If the antenna in this band is structured to resonate at the used wavelength in free space, the gain in free space will be close to that of a dipole antenna. However, when worn on the arm, the human body acts in the same manner as metal and an image of the opposite phase is generated, so that the gain is reduced by 25 dB or more as compared with that in free space.

As an antenna that does not cause gain deterioration in the vicinity of the human body, there is an antenna in which the human body itself is electrically connected to a power feeding unit and the human body is used as an element of the antenna, which is mainly used in the medium-wave band.

[0004]

[Problems to be solved by the device]

 The conventional human body having an antenna element has a drawback that the gain of the antenna is lowered at a frequency higher than VHF. Therefore, an object of the present invention is to provide a wristwatch type receiver having high sensitivity even at a high frequency of VHF or higher.

[0005]

According to the invention of claim 1, one surface of a case having a built-in radio receiver is made conductive, and one end of each band is attached to both sides of the case. By winding it around the arm, the conductive surface of the case can be brought into contact with the arm, and the length within the case is about 0.05 to 0.15λ (λ: wavelength used by the wireless receiver). Each part of the conductive wire is housed in the conductive surface at substantially uniform intervals (heights), one end of the conductive wire is connected to a feeding point of the wireless receiver, and the other end is connected to the conductive surface.

According to the second aspect of the present invention, the first helical antenna is supported on one side of the band, extends along the longitudinal direction of the band, one end is connected to the conductive surface, and the second helical antenna is on the band side. It is supported by the other, extends in its longitudinal direction, and has one end connected to the common potential point of the radio receiver. The first and second helical antennas, the conductive surface and the conducting wire are made to resonate at the used wavelength in free space. According to the invention of claim 3, the second helical antenna is omitted.

According to the invention of claim 4, the first zigzag antenna is supported by one of the bands, is extended back and forth in the width direction thereof and is extended along the longitudinal direction thereof, and one end thereof is connected to the conductive surface. The second zigzag antenna is supported by the other side of the band, extends in the longitudinal direction while being folded back and forth in the width direction, and one end of the second zigzag antenna is connected to the common potential point of the radio receiver. The two zigzag antennas, the conductive surface and the wires are made to resonate at the used wavelength in free space. According to the invention of claim 5, the second zigzag antenna is omitted.

[0008]

【Example】

 FIG. 1 shows an embodiment of this invention. The case 11 shows a state in which the upper lid is removed. In this example, the case is a rectangular plate-like case, and has a size of, for example, 0.037λ × 0.037λ × 0.00 8λ (λ: wavelength used by the wireless receiver). Although not shown in the figure, a wireless receiver is built in the case 11. That is, the wiring board 12 is arranged on the bottom plate in the case 11 in parallel with the bottom board, and a wireless receiver (not shown) is mounted on the wiring board 12 to form a receiver mounting board. An antenna feeding part (not shown) of the receiver is connected between the feeding point 13 and the common potential point 14 of the wireless receiver. One end of each of the bands 15 and 16 is connected to the side plates at both ends of the case 11, and the case 15 can be attached to the arm 17 by winding the bands 15 and 16 around the arm 17 of the human body.

One surface of the case 11, which is a bottom surface in this example, is a conductive surface 18. Therefore, in this example, the bottom plate of the case 11 is the metal back cover 19. When the case 11 is attached to the arm 17 with the bands 15 and 16, the conductive surface 18 is brought into contact with the arm 17. In this example, the case 11 is made of synthetic resin insulating material except for the back cover 19. A conductive wire 21 is arranged in the case 11, one end of the conductive wire 21 is connected to the feeding point 13, and the other end is connected to the conductive surface 18, which is the back cover 19 in this example. The length of the conductive wire 21 is about 0.05 to 0.15λ, and the distance D ₁ between each part of the conductive wire 21 and the conductive surface 18, that is, the height with respect to the conductive surface 18 is substantially uniform. In this example, D ₁ = 0.005λ. Further, in this example, the conductive wire 21 runs along the inner peripheral surface of the case 11.

The result of measuring the gain of the antenna when the wristwatch type receiver is worn on the wrist by changing the length of the conductor 21 connecting the feeding point 13 and the case back (conductor plate) 19 2A. The horizontal axis is the length of the conducting wire 21, and the vertical axis is the gain when the loop antenna built into the conventional portable receiver (size 0.08 x 0.05 x 0.01λ) is mounted in the chest pocket. The relative gain, that is, 0 dB is the conventional loop antenna gain. Line 22 also shows the gain of the loop antenna built in the case whose size is one-third (0.04 × 0.04 × 0.008λ) of the conventional case when the chest pocket is attached. ..

By changing the length of the conductor 21 that connects the feeding point 13 and the back cover 19 of the configuration of FIG. 1, the input impedance of the antenna viewed from the feeding point 13 changes. This changes the matching condition of the circuit. From this measurement result, the gain peaks when the length is about 0.13λ, and the impedance matching condition is optimized. In the case of 1/3 the volume of the conventional radio, it is 5 dB higher than that of the internal loop antenna. It is possible to obtain a gain 1 dB higher than that of the loop antenna built in the conventional case. The length of the conductive wire 21 is preferably 0.07 to 0.15λ, since a gain larger than that of the loop antenna built in the case of the volume 1/3 can be obtained.

The effect of the case back cover 19 can be explained as follows. As shown in FIG. 2B, the center line 24 of the coaxial line 23 is extended by 0.005λ, and the conductor plate 25 is attached to the tip of the center line 24 so that the conductor plate 25 is brought into contact with the arm 17. The change in gain when the area is changed is shown in FIG. 2C. The horizontal axis represents the area of the conductor plate 25, and the vertical axis represents the relative gain based on the measured value of the conductor plate area of 5.2 × 10 ⁻⁴ λ ² . From the figure, it can be seen that the gain when the arm is worn is increased by increasing the size of the conductor plate 25. Increasing the area of the conductor plate 25 to increase the contact area with the human body further increases the loading impedance and further improves the matching characteristics, thereby increasing the gain.

If the case 11 is an insulating material and there is no possibility of contact with a conductive material, the conductive wire 21 may not be covered with an insulating coating. FIG. 3 shows another embodiment of the present invention, in which parts corresponding to those in FIG. 1 are designated by the same symbols. In this example, the helical antennas 26 and 27 are embedded in the bands 15 and 16 on both sides, respectively. In the embodiment of FIG. 1, a high gain can be obtained when the conductive surface 18 of the radio case 11 is in contact with the human body, but the gain decreases when the case 11 is separated from the arm. This embodiment solves this problem. Also in this example, the feeding point 13 of the wireless receiver exists at a corner portion of the case 11 having a size of 0.037λ × 0.037λ × 0.008λ. The length of the conductive wire 21 is 0.12λ, the wire diameter is 0.005λ, and the height D ₁ from the bottom surface of the case 11 is 0.005λ.

The helical antennas 26 and 27 are arranged along the longitudinal directions of the bands 15 and 16, respectively, and the cross-sectional area perpendicular to the axis of the helical antenna is 0.02λ × 0.002λ. Are embedded in conductor bands 15 and 16, respectively, the helical antenna 20 on the side opposite to the feeding point 13 is connected to the common potential point 14 of the radio receiver, and the other helical antenna 27 is on the back of the case 11. It is connected to the lid 19. The pitch p of each helical antenna 26, 27 is 0. The number of turns is 004λ, the number of turns is 11, the wire diameter is 0.0005λ, and the helical antennas 26 and 27 on both sides, the back cover (conductor plate) 19 of the case 11, and the lead wire 21 connecting the feeding point 13 and the back cover 19 are connected. All of the two parts resonate at the receiver wavelength λ in free space. The operation of this antenna will be described below.

In a free space, this antenna operates as a helical antenna that is fed at the center of the antenna. Selection of structural parameters in which the helical antennas 26 and 27 in the band resonate will be described with reference to measurement data. Fig. 4A shows a measurement of the relationship between the helical cross-sectional area A, the pitch p, and the number of turns when the helical antenna resonates. The horizontal axis represents the standardized spiral area A / λ ² , the vertical axis represents the pitch p / λ, and the parameter is the number of turns N 2. If the number of turns N is constant, it is necessary to reduce the pitch p as the spiral area A is increased. If the pitch p is constant, it is necessary to reduce the number N of turns as the spiral area A is increased. , If the area A is kept constant, the number of turns N needs to be reduced as the pitch p is increased. By selecting the cross-sectional area A, the pitch p, and the number of turns N of the helical antenna in the relationship shown in FIG. 4A, it is possible to resonate at the used frequency and obtain a high gain in free space.

FIG. 4B is a diagram showing the input impedance of the square helical antenna in the resonance state. The horizontal axis is the standardized spiral area A / λ ² , the vertical axis is the pitch p / λ, and the numerical value entered inside is the input impedance. For example, the numerical value 14.4 is the input impedance when A / λ ² is about 40 × 10 ⁻⁶ and p / λ is 4 × 10 ⁻³ . A straight line 28 shows a line satisfying the empirical formula p / λ = 150 A / λ ² . If the structural parameters of the helical antenna are selected so that they are above the straight line 23, that is, in the shaded region that satisfies p = 150 A / λ ² , the input impedance at resonance becomes 20 Ω or more. In the limit of A = 0, this antenna is a dipole antenna, and the input impedance is about 70Ω. When the input impedance is 20 to 100Ω, the VSWR (voltage standing wave ratio) generated at the connection between the antenna and the standard input impedance of the receiver (generally 50Ω) is 2 or less. Therefore, if the structural parameters are selected so that the relationship between the helical pitch p, the helical cross-sectional area A, and the used wavelength λ satisfies p> 150 A / λ ² , the antenna and receiver can be directly connected without a matching circuit. can do.

Further, it will be explained that the above relationship is the same even if the region that determines the helical area A of the helical antenna is not a square but a rectangle, that is, a flat helical antenna. The input impedance when the helical antenna is placed in free space is calculated by dividing the spiral area A and the length a of the long side of the area that determines the spiral area A by the length of the short side b. / B (square δ = 1) and the measured results are shown in FIG. 4C for the pitches p = 4λ × 10 ⁻³ and p = 8λ × 10 ⁻³ . In FIG. 4C, the spiral area is A / λ ² = 10 × 10 ^-6 , the input impedance is almost 31Ω regardless of the aspect ratio, and the aspect ratio changes when A / λ ² is about 40 × 10 ^-6. It can be said that the input impedance hardly changes even if it is made.

Next, the operation of the antenna of this embodiment when worn on the arm will be described. In this example, a back cover (conductor plate) 19 is provided in the middle of the helical antenna 27 and the feeding point 13, and the human body is contacted through the back cover 19, so that the load of the human body is in the middle of the antenna. It becomes a loaded antenna. In general, the characteristics of the load-loaded antenna change depending on the position where the load is loaded. In this embodiment, the conductor 21 that electrically connects the feeding point 13 and the back cover 19 is installed along the inner peripheral wall of the case 11 so that it does not interfere with the storage of the receiver and is not loaded by the human body. The structure is such that the position can be selected in the optimum state. Further, the feeding to the helical antenna 27 embedded in the band 16 can be easily realized by bringing one end of the helical antenna 27 into contact with the case back (conductor plate) 19 of the case.

FIG. 5A shows the gain when the length of the conducting wire 21 connecting the feeding point 13 and the case back 19 when the antenna of this embodiment is worn on the arm is changed, and its 0 dB is shown in FIG. 2A. Is the same as that of. The horizontal axis represents the length of the conducting wire 21, and the vertical axis represents the relative gain based on the gain of the loop antenna built in the conventional radio case. By loading the human body in the middle as in this embodiment, the impedance changes and the impedance matching with the receiver is improved, so that the length of the lead wire 21 is around 0.13λ and the case volume is smaller than the conventional case. It is possible to improve the gain by 4 dB as compared with a loop antenna built in a small case of 1/3.

The effect of the conductor plate of the case back cover 19 can be explained as follows. FIG. 5B is a diagram showing a change in gain when the area of the back cover 19 of the embodiment shown in FIG. 3 is changed. The horizontal axis is the normalized area of the back cover, and the vertical axis is the relative gain based on the gain of the loop antenna built into the conventional radio case. It can be seen that the antenna gain further increases as the size of the back cover (conductor plate) increases. This is similar to the fact that the input impedance becomes low when the dipole antenna approaches the human body, and the input impedance changes when the helical antenna approaches the human body. However, by loading the human body as in this embodiment, a large impedance is loaded on the antenna, and the matching characteristic of the receiver is improved. In addition, increasing the contact area with the human body further increases the loading impedance, which further improves the matching characteristics. It should be noted that if the distance between the contact point between the conductor wire 21 and the case back cover 19 and the contact point between the helical antenna 27 and the back cover 19 is changed, the amount of current on the antenna flowing through the back cover 19 and flowing through the human body changes. The impedance may also be adjusted by changing the distance between the two contacts.

As described above, it is possible to configure an antenna having a high antenna gain both when the arm is attached and when the arm is attached and detached. FIG. 6 shows still another embodiment of the present invention. This example is an example in which the helical antenna 26 connected to the common potential point 14 of the receiver is removed in the embodiment shown in FIG. As shown in FIG. 5C, the gain in such a configuration is lower in free space than in the example shown in FIG. However, the gain when worn on the arm does not change, and the level of the free space is about 5 dB higher than the gain when worn on the arm, which is practically sufficient.

FIG. 7 shows still another embodiment of the present invention. In this example, zigzag antennas 31 and 32 are embedded in bands 15 and 16 instead of helical antennas, respectively. The zigzag antennas 31 and 32 extend in the longitudinal direction while folding the bands 15 and 16 back and forth in the width direction of the bands. The zigzag antennas 31 and 32 in the band are band-shaped conductors having a width La of 0.03λ, a pitch p of 0.004λ, a folding number M of 21.5, and a wire diameter of 0.001λ. The length of the conductor 21 that connects the feeding point 13 and the case back (conductor plate) 19 is 0.06λ. The zigzag antennas 31 and 32 on both sides resonate with the used wave length in a free space at three portions, that is, the case back (conductor plate) 19 of the case and the conductor 21 connecting the feeding point 13 and the case back 19.

The shape of the zigzag antenna is selected so as to act as one antenna that resonates substantially at the used wavelength λ when viewed from the feeding point 13 and the common potential point 14 in free space. For example, when a strip-shaped conductor with a line width of 0.001λ is folded back and the antenna is connected to a power supply between the inner ends of a pair of zigzag antennas with a uniform width W, the antenna width W, pitch p, and one side 8A and the number of turns M of the zigzag antenna of FIG. 8A have a relationship shown in FIG. The curve in FIG. 8A shows the relationship between W and p for resonating when the number of cuts M is a parameter. With this configuration, the zigzag antenna can achieve the same performance as the helical antenna.

Further, FIG. 8B shows the results of measuring the input impedance of the zigzag antenna used in the experiment of FIG. 8A for various antenna widths W and pitch p. The line 33 in the figure is a line of W = 0.03λ, and assuming that the zigzag antenna has an antenna width W <0.003λ, the input impedance at resonance in free space becomes 20Ω or more, and the standard input impedance (50Ω). It is possible to connect directly to the receiver without using a matching circuit.

FIG. 8C shows the result of measurement of the gain when the arm is worn when the length of the conducting wire 21 that connects the feeding point 13 and the case back (conductor plate) 19 is changed. From the figure, by setting the length of the conducting wire 21 to 0.06λ, a gain improvement of about 2 dB can be realized as compared with a loop antenna built in a small case with a volume of 1/3, and 0.05 to 0.11λ, The gain is larger than that of the above loop antenna.

As described above, it is possible to construct an antenna having a high gain both when the arm is attached and when the arm is attached and detached, like the helical antenna. FIG. 9 shows still another embodiment of the present invention. In this example, each antenna width La of the zigzag antennas 31 and 32 is gradually changed. This zigzag antenna also has a relationship similar to the relationship shown in FIG. 8, and the zigzag antenna selects an antenna width W, a pitch p, and a folding number M for the used wavelength λ so that the zigzag antenna is in a substantially resonant state. Be done.

In this example, the width W of the zigzag antenna is 0.03λ on the case side, 0.0019λ on the free end side of the band, the folding pitch p is 0.0025λ, and the wire diameter is 0.0004λ. , And the number of turns M is 26. Similarly, as to the length of the lead wire 21 that connects the feeding point 13 and the case back cover 19, the position where the gain is maximized when the receiver is worn on the arm is experimentally selected as shown in FIG. , 0. It is set to 06λ. The gain of this antenna was the same as that of the other examples. In FIGS. 7 and 9, the zigzag antenna 31 connected to the common potential point 14 may be omitted.

From the results of FIGS. 2A, 5A, 8C, and 10 described above, the length of the conductor wire 21 that connects the feeding point 13 of the receiver and the case conductor plate (back cover) is 0.05λ. ˜0.15 λ.

[0029]

[Effect of the device]

 As described above, by using the wristwatch type receiver of the present invention, a receiver that maintains high sensitivity even in the VHF band can be realized. For this reason, the power consumption of the receiver can be reduced, the battery can be made smaller, and the receiver can be made smaller and lighter. In addition, with higher sensitivity, call quality will improve and high-performance services will become possible. Furthermore, by attaching a helical antenna or zigzag antenna to the band and using them together, it is possible to realize a receiver that maintains high sensitivity even when wearing and wearing the arm.

[Brief description of drawings]

1 is a perspective view showing an embodiment of the invention of claim 1;

2A is a diagram showing a change state of the antenna gain when the length of the conducting wire 21 of FIG. 1 is changed, and B is a metal plate attached to the tip of the rotating monopole antenna, and the arm is brought into contact with the metal plate. FIG. 3C is a perspective view, and C is a diagram showing a gain change with respect to the area of the metal plate.

FIG. 3 is a perspective view showing an embodiment of the invention of claim 2;

FIG. 4A is a diagram showing a relationship between a spiraling area A and a pitch p when a winding N in a resonance state of the square helical antenna is a parameter, and B is an input of a square helical antenna having various spiraling areas A and various pitches p. Figure showing impedance,
C is a diagram showing various aspect ratios of the helical antenna and input impedances at various helical areas A. FIG.

5A is a conducting wire 2 with the receiver of FIG. 3 attached to an arm.
1 is a diagram showing an antenna gain change with respect to the length of 1, a diagram showing an antenna gain with respect to an area change of the back cover 19, and a diagram showing a comparison of antenna gains between the receiver of FIG. 3 and the receiver of FIG. 6. is there.

FIG. 6 is a perspective view showing an embodiment of the invention of claim 3;

FIG. 7 is a perspective view showing an embodiment of the invention of claim 4;

FIG. 8A is an antenna width W with a parameter of the number of turns M in the resonance state of the zigzag antenna, and a pitch p.
, B is a diagram showing the input impedance of a zigzag antenna having various antenna widths W and various pitches p,
FIG. 8C is a diagram showing the gain of the antenna shown in FIG. 7 with respect to the length of the conducting wire 21 when the antenna shown in FIG. 7 is worn on the arm.

FIG. 9 is a perspective view showing another embodiment of the device of claim 4;

FIG. 10 is a conductor wire 2 of the antenna shown in FIG.
The figure which shows the gain with respect to the length of 1.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hitoshi Itakura 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Kenichi Kagoshima 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo No. Japan Telegraph and Telephone Corporation (72) Inventor Kazuki Watanabe 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd. (72) Hideo Nakanishi Tsunashima-east, Kohoku-ku, Yokohama-shi, Kanagawa 4th-3rd No. 1 Matsushita Communication Industrial Co., Ltd.

Claims (5)

[Scope of utility model registration request] 1. A case having a built-in wireless receiver, one surface of which is electrically conductive, and one end of each of which is attached to both sides of the case so that the electrically conductive surface of the case is wound around an arm of a human body. A pair of bands that can be provided, and provided in the case, one end is connected to the feeding point of the wireless receiver, the other end is connected to the conductive surface of the case, the gap between the conductive surface A wristwatch-type receiver comprising: a conductor wire having a length of about 0.05 to 0.15λ (λ: wavelength used by the wireless receiver), which is substantially uniform. 2. A first helical antenna having one end connected to the conductive surface, supported by one of the bands, and extending along the longitudinal direction of the band, and one end having a common potential point of the radio receiver. A second helix that is connected to the other of the bands, extends along the longitudinal direction of the band, and resonates with the first helical antenna, the conductive surface, and the lead wire in the free space at the use wavelength λ in the free space. The wristwatch-type receiver according to claim 1, further comprising an antenna. 3. The wristwatch type receiver according to claim 2, wherein the second helical antenna is removed. 4. A first zigzag antenna, one end of which is connected to the conductive surface, is supported by one of the bands, is folded back and forth in the width direction of the band, and extends along the longitudinal direction thereof, Is connected to a common potential point of the radio receiver, is supported by the other side of the band, and is extended along the longitudinal direction while being folded back and forth in the width direction, the first zigzag antenna, the conductive surface, and The wristwatch type receiver according to claim 1, further comprising a second zigzag antenna which resonates substantially at the used wavelength λ in free space together with the conductor. 5. The wristwatch type receiver according to claim 3, wherein the second zigzag antenna is removed.