JPH0567910A - Portable radio equipment - Google Patents

Abstract

PURPOSE:To realize a small sized radio equipment with a high gain by holding a radio equipment circuit in a case having a conductor part, connecting the conductor part in a ring so as to form a loop antenna and providing a conductor plate in capacitance coupling with a battery in the antenna. CONSTITUTION:A capacitor section 11 whose static capacitance is 1-several tens of pF is formed by a gap 7 of nearly 0.0005lambda (lambda is a transmission/reception wavelength of a loop antenna set equivalent to, e.g. 300MHz) between a button battery whose diameter is 0.02lambda and a bottom 6 in non-contact with the battery. The capacitance is used for matching the loop antenna, the negative pole of the radio equipment circuit is connected to the capacitor and it is connected in series with the loop antenna element, thereby allowing the design including the battery without close provision of the battery and the loop antenna. Thus, the adverse effect by the battery is minimized and the antenna efficiency is improved. Thus, the gain of the antenna including the matching circuit is set almost equal to the gain of a conventional antenna when the battery is removed and no deterioration is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable wireless device, and more particularly to miniaturization of an ultra-small portable wireless device having a loop antenna inside.

[0002]

2. Description of the Related Art Generally, a small loop antenna is mainly used as an antenna section of a conventional small portable radio apparatus whose shape is sufficiently smaller than a wavelength for transmitting and receiving. The loop antenna is arranged in the housing at a position as far as possible from internal components such as a substrate and a battery.

FIG. 1 shows a configuration of an example of a conventional loop antenna.
It shows in 0.

In this structure, a radio circuit board 2 and a battery 3 are arranged inside a casing 1, and a ring 4 is formed of a conductive wire 4 which is electrically separated from the power feeding portion 2a of the radio circuit substrate 2. Loop antenna is provided.

The size of the loop antenna is about 0.07λ × 0.01λ in the case of a radio paging transceiver. The antenna input resistance of the loop antenna is usually 1Ω or less, which is low with respect to the impedance of the radio circuit. Therefore, as shown in FIG. 7, the loop antenna and the radio device circuit are matched by using a matching circuit in which variable capacitors 27 and 28 are connected to the capacitor 29 in series and in parallel.

[0006]

However, the portable wireless device described above is required to be further miniaturized, and the density of mounting on the housing such as the circuit parts and batteries constituting the wireless device becomes higher. ing. For this reason, when the loop antenna is incorporated in the housing, the metal parts of the substrate and circuit parts are close to each other, and especially when the battery of the container covered with metal becomes parallel to the loop antenna, the mutual relationship between them causes scattering. In a free space where adverse effects such as absorption occur, and the parts etc. are not close to the loop antenna,
Even if the gain can be secured, the antenna gain deteriorates by 1 to 5 dB if it is incorporated in the housing, and the desired gain may not be secured in some cases.

Therefore, an object of the present invention is to provide a portable radio device having a gain level higher than that of a conventional one even if it is miniaturized.

[0008]

In order to achieve the above object, the present invention provides a wireless device held inside a housing having a conductive portion, and the wireless device and the conductive portion of the housing are annular with a conductor. There is provided a portable wireless device including a loop antenna formed by connecting to a battery, a battery, and a conductive plate capacitively coupled to the battery in a loop of the loop antenna.

[0009]

In the portable wireless device having the above-described configuration, the loop antenna is configured by using the metal part of the housing, and the gap between the battery and the bottom is used in place of the capacitor of the matching circuit and the wireless device circuit is formed. The antenna gain including this matching circuit is prevented from being deteriorated by approaching the battery and the mounted components.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a radio apparatus as a first embodiment of the present invention. Here, FIG. 1A is a cross-sectional view seen from the front, FIG. 1B is a top view, and FIG. 1C is a perspective view. An equivalent circuit of this wireless device is shown in FIG.

In this configuration, the radio circuit board 2 and the battery 3 whose container is made of metal are housed in the housing 5. The housing 5
Has only the bottom portion 6 made of metal, and the side wall portion and the upper surface portion are made of an insulator.

The lower surface of the battery 3 has the bottom portion 6
Is fixed in a non-contact manner with a gap 7 therebetween.
The battery 3 is connected to the wireless circuit board 2 by a loop element 8 made of a metal wire or a metal plate, and is similarly connected to the bottom portion 6 by a loop element 9 from the wireless circuit board 2 to form a loop antenna.

As shown in the equivalent circuit of FIG. 2, when the transmission / reception wavelength of this loop antenna is, for example, 300 MHz, 0 between the button battery having a diameter of 0.02λ and the non-contact bottom portion 6 is set. Gap 7 of about 0.0005λ
As a result, the capacitor section 11 having a capacitance of 1 to several tens of pF is formed. Use this capacitance for matching the loop antenna, connect the negative pole of the wireless device circuit,
By connecting and arranging the capacity in series with the loop antenna element, the loop antenna does not come close to the battery, and the battery can be designed including the battery. Therefore, the adverse effect of the battery can be minimized and the antenna efficiency can be reduced. Can be higher.

Therefore, this wireless device uses the capacitance of the capacitor section 11 instead of the capacitor 29 of the conventional matching circuit shown in FIG.
7 and 28 perfectly match the radio circuit. The antenna gain including this matching circuit is, as shown in FIG.
The gain is almost the same as the conventional antenna with the battery removed, and there is almost no deterioration in the gain that occurs when the antenna element approaches the battery.

Next, FIG. 3 shows a cross-sectional view of the structure of the wireless device of the second embodiment as seen from the front. Here, constituent members of the second and subsequent embodiments that are equivalent to those of the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

In this wireless device, the entire bottom portion 6 of the housing 5 shown in the first embodiment is made of metal, whereas only the bottom portion 12 facing the battery 3 is made of metal and the other portions are made of metal. Case 1
The same effect can be obtained by forming the three parts with an insulator. The battery 3 is connected to the wireless circuit board 2 by a loop element 14 made of a metal wire or a metal plate, and is similarly connected from the wireless circuit board 2 to the bottom portion 12 by a loop element 15 to form a loop antenna.

Next, FIG. 4 is a diagram showing the structure of a radio apparatus as a third embodiment of the present invention. Here, FIG. 4A is a sectional view seen from the front, and FIG. 4B is a perspective view. In this wireless device, only the bottom portion 6 of the casing is made of metal in the first embodiment, but the upper portion 16 facing the bottom portion 6 is also made of a metal plate to obtain the same effect.

In the first and second embodiments described above, since the loop element is circulated in the housing and wired, the loop element is a relatively long metal wire (metal plate). Since the upper part 16 becomes the element of the loop element, it is possible to form the loop antenna by connecting the upper part 16 and the bottom part 6 with the short-circuit element 18 made of metal at the shortest. Therefore, further miniaturization can be realized.

FIG. 5 shows a sectional view of the structure of a wireless device as a fourth embodiment of the present invention, as seen from the front.

In the fourth embodiment, a bottom metal plate 21 and a top metal plate 23 are provided inside a bottom 20 and a top 22 of a casing made of an insulator of a radio device so as to face each other, and these are short-circuit elements. 25 is connected to form a loop antenna.

Next, FIG. 6 shows, as a fifth embodiment, the bottom portion 6 (metal) of a wireless device having the same structure as the wireless device of the first embodiment is brought into contact with a living body 26 such as a human body. That is, the wireless device is attached to the arm or the like so that the entire surface or a part of the surface of the bottom portion 6 comes into contact with the arm 6 to widen the band of signals to be transmitted and received. FIG. 9A shows the characteristic of return loss when it is attached to a human body, and FIG. 9B shows the characteristic of impedance, both of which have a variable frequency range of 200.
~ 400 MMHz.

In the fifth embodiment, for example, when a metal casing forming a part of the loop antenna is brought into contact with a living body such as a human body, when matching is performed by a matching circuit, a return loss of -10 dB is obtained. At around 250MHz at 10
A high bandwidth of about 0 MHz can be obtained.

As described above, according to the present invention, the loop athena can be housed in the radio equipment casing which is miniaturized and in which the packaging density of the components constituting the radio equipment circuit is increased, and the sensitivity is high. A wireless device can be realized.
By using the present invention, compared to the conventional radio, there is no gain deterioration due to peripherally arranged parts, a gain improvement of 1 to 5 dB is expected, and it becomes possible to downsize the radio and save power, and A margin can be given to the wireless line, which has the effect of improving communication quality and expanding the communication area. Also,
If a metal housing that forms a part of the loop antenna is attached so as to be in contact with a living body, a very wide band can be secured with an antenna that is very small compared to the wavelength for transmitting and receiving. Further, the portable wireless device of the present invention can also be downsized because the space for housing the antenna can be reduced.

Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[0026]

As described above in detail, according to the present invention, it is possible to provide a portable radio apparatus which is miniaturized and has a gain level higher than the conventional one.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wireless device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of the first embodiment.

FIG. 3 is a diagram showing a configuration of a wireless device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a wireless device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a wireless device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a wireless device in which a bottom portion of a housing is brought into contact with a living body as a fifth embodiment of the present invention.

FIG. 7 is a diagram showing an example of a matching circuit between an antenna and a radio circuit.

FIG. 8 is a diagram showing impedance characteristics including the battery in the first embodiment.

9 (a) is a diagram showing a return loss characteristic when it is mounted on a human body, and FIG. 9 (b) is a diagram showing its impedance characteristic.

FIG. 10 is a diagram showing an example of a configuration of a conventional loop antenna.

[Explanation of symbols]

1, 5, 13 ... Casing, 2 ... Radio circuit board, 2a, 10
... power feeding part, 3 ... battery, 4 ... conducting wire, 6, 12, 20 ... bottom part, 7 ... gap, 8, 9, 14, 15 ... loop element, 11 ... capacitor part, 16, 22 ... top part, 18 ...
Short-circuit element, 21 ... Bottom metal plate, 23 ... Top metal plate, 26
... living body, 27, 28 ... variable capacitor, 29 ... capacitor.

Claims (2)

[Claims] 1. A radio unit held inside a casing having a conductive unit, a loop antenna formed by connecting the radio unit and the conductive unit of the casing in an annular shape with a conductor, and a loop antenna of the loop antenna. A portable wireless device comprising a battery and a conductive plate capacitively coupled to the battery in an annular shape. 2. A loop formed by connecting a wireless means held inside a housing having a conductive portion and a conductive portion having a surface of the wireless means and the housing in contact with a living body with a conductor in an annular shape. A portable wireless device comprising an antenna and a battery and a conductive plate capacitively coupled to the battery in a loop of the loop antenna.