JPH0897621A - Antenna system and portable radio equipment provided with it - Google Patents

Abstract

PURPOSE: To make the size of a portable radio equipment small by obtaining a more excellent antenna characteristic (gain) in the portable radio equipment to effectively use a space without losing the antenna characteristic. CONSTITUTION: Two conductor plates 1a, 1b are placed nearly in parallel with a gap inbetween, and one-side ends of the conductor plates 1a, 1b are short- circuited by a short-circuit plate 3. On the other hand, a tuning capacitive element 4 is loaded on the other side of the short-circuiting plate 3. Then feeding point positions 8a, 8b on the conductor plates connecting to a radio equipment circuit section 5 differ from the position to which the capacitive element 4 is loaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small portable wireless device, and more particularly to an antenna device for improving antenna characteristics.

[0002]

2. Description of the Related Art Among the antenna devices for portable radio equipment, as an antenna device using two conductor plates placed substantially parallel to each other, two antenna devices are disclosed in Japanese Patent Laid-Open No. 1-241927. An example in which the conductor plate is placed with a gap to short-circuit the conductor plate at the short-circuit portion, and a capacitive element is loaded at the feeding point position to form a loop antenna as shown in the circuit diagram of the same publication, Further, Japanese Patent Laid-Open No. 6-244618 discloses an example of a loop antenna in which a short-circuit conductor that short-circuits a feeding point and two rectangular conductor plates is arranged near a diagonal position.

[0003]

However, in the antenna device of the portable wireless device having such a conventional loop antenna, the antenna size is limited to a small size because it is for a small portable wireless device. , It was difficult to obtain the necessary and sufficient antenna gain, and it was difficult to maintain the satisfactory communication quality of the radio.

Therefore, the present invention solves such a problem by providing an antenna device for a portable radio with a simple structure and using a slot antenna mode to obtain a larger antenna gain than before. It is intended to be provided. Another object of the present invention is to provide a configuration of a portable wireless device that can effectively use the space inside the wireless device main body without deteriorating the antenna characteristics and can be downsized.

[0005]

In order to achieve the above object, the antenna device of the present invention comprises two conductor plates which are placed substantially in parallel with each other with a gap between them, and conductors at the end portions of the conductor plates. In an antenna device having a short-circuit plate in which plates are short-circuited and a capacitive element loaded at the end of the conductor plate on the opposite side of the short-circuit plate, 2
It is characterized in that the feeding point position on the one conductor plate is different from the position where the capacitive element is loaded.

Further, it is desirable that the two conductor plates are quadrangular and that the short-circuit plate and the capacitive element are respectively disposed near the diagonal positions of the conductor plates.

Further, a portable wireless device equipped with this antenna device has a portable wireless device circuit section formed between two conductor plates,
Further, it is desirable to provide a cutout portion in a portion of at least one conductor plate which overlaps with the portable wireless device circuit portion.

[0008]

According to the configuration of the portable wireless device of the present invention, it is considered that the loop antenna and the slot antenna are combined in order to improve the antenna characteristics, and the characteristics of both are optimally added to each other to make a large difference. It is estimated that the antenna gain can be obtained. Further, the influence of the radio device circuit section on the antenna can be reduced.

The principle will be described below. In the antenna device having the conventional configuration, the loop antenna is made to function by the two conductor plates and the short circuit portion. This antenna device has
A capacitive element is loaded to tune to a desired frequency, which is connected to the feeding point of the antenna by a feeding line and can be said to be electrically located at the same position.

On the other hand, in the antenna device of the present invention, the position of the feeding point of this antenna is displaced from the position on the conductor plate where the capacitive element is loaded, and the positions of the two are separated. As a result, it becomes possible to make the slot portion formed around the side surface portion of the antenna device sandwiched by the two conductor plates function as a slot antenna. As a result, it is considered that both the loop antenna mode and the slot antenna mode are added, and a larger antenna gain can be obtained than in the case of only the loop antenna.

FIG. 6 shows an example of the antenna radiation directivity pattern measurement according to the conventional example and the present invention. The vertical polarization components in the XY plane are shown and standardized by the maximum antenna gain. The solid line portion 110 is the measurement result of the present invention, and the dotted line portion 111 is the measurement result of the conventional example, and the conditions such as the size and frequency of the antenna are the same. Although the X-axis direction in which the capacitive element is loaded is the maximum radiation direction, the antenna gain of the present invention is larger than that of the conventional example, and the radiation pattern is generally round. It can be seen that the antenna characteristics are improved by combining the slot antenna with the conventional loop antenna.

The capacitive element loaded between the conductor plates has the purpose of tuning the antenna to a desired frequency by adjusting the capacitance value even in the slot antenna, and the loading position depends on the distribution of the current flowing through the conductor plate. Since the balance is achieved, the antenna characteristics are most improved on the side opposite to the short-circuit plate,
desirable.

Further, according to the present invention utilizing the above principle, an attempt is made to obtain a larger antenna gain by arranging the capacitive element and the short-circuit plate. The operation will be described. FIG. 7A is a plan view of the antenna device, and FIG.
(B) is the side view. Two conductor plates 112a and 112b placed substantially parallel to each other, a short-circuit plate 113, and a capacitive element 1
It is composed of 14. The slot antenna is a magnetic field detection type antenna, and the magnetic field component 115 in the case of vertical polarization has a horizontal direction (Y-axis direction) as shown in the figure. Due to this magnetic field component, currents in the same direction flow in the conductor plates 112a and 112b in the slot antenna mode and the loop antenna mode, and both are added to obtain a large antenna gain.

FIG. 8 (a) is a plan view of the further improved antenna device of the present invention, and FIG. 8 (b) is a side view thereof. Since the structure is similar to that of FIG. Is attached. In FIG. 8, the short-circuit plate 113 and the capacitive element 1
Since 14 are arranged in the vicinity of the diagonal positions of the rectangular conductor plates 112a and 112b respectively, the substantial opening area 116 (hatched portion) of the loop portion on the side surface can be secured to the maximum. The larger the aperture area of the loop antenna, the larger the antenna gain. Therefore, the characteristics of the loop antenna can be improved, and a larger antenna gain can be obtained even though the antenna dimensions do not change. The effect of the configuration of the optimum antenna device as shown in FIG. 8 is that the maximum antenna gain is improved by about 3 dB as compared with the example of FIG.

[0015]

【Example】

(Embodiment 1) An embodiment of an antenna device of the present invention and a portable wireless device including the antenna device will be described in detail with reference to the drawings. Figure 1
1 is a schematic perspective view of a portable wireless device according to an embodiment of the present invention. The two conductor plates 1a and 1b are placed substantially parallel to each other with a gap 2. The material of the conductor plates 1a and 1b is copper, stainless steel or the like. If made of copper, a relatively large antenna gain can be obtained because of low electric resistance, and if made of stainless steel, it has excellent rust resistance and high durability. There are features. Further, if there is no electrical influence, the outer sides of the conductor plates 1a, 1b and the outer side of the radio device circuit section 5 may be covered with a plastic member or the like in order to improve the appearance. Although the conductor plate 1a and the conductor plate 1b are depicted separately in this figure for the sake of explanation, they are actually connected by the short-circuit plate 3 at the ends.
The short-circuit plate 3 need not be formed integrally with the conductor plates 1a and 1b, but may be formed by means such as screwing as long as the conductor plates 1a and 1b can be electrically conducted. With this configuration, the present antenna device forms the slot portion around the side surface portions of the conductor plates 1a and 1b.

The capacitive elements 4 loaded on the ends of the conductor plates 1a and 1b and on the opposite side of the short-circuit plate 3 are for tuning to a desired frequency, and are fixed capacitors or variable capacitors for fine adjustment. It may be a capacitor or the like. Further, a varactor diode may be used to support electronic tuning. The wireless device circuit section 5 includes conductor plates 1a and 1b via power supply lines 7a and 7b.
And 8a and 8b at the feeding points, respectively.
When the feeding points 8a and 8b are the same as or very close to the loading position of the capacitive element 4, the present antenna device does not function as a slot antenna but functions only as a loop antenna, and the antenna gain is reduced. Therefore, by properly shifting the positions of the feeding points 8a and 8b from the loading position of the capacitive element 4 on the conductor plates 1a and 1b as in this example, the present antenna device can be surely functioned as a slot antenna. You can Further, since the feeding impedance of the conductor plates 1a and 1b also changes depending on the feeding point position, it is possible to arbitrarily adjust the impedance so that impedance matching with the radio circuit portion 5 can be easily achieved.

The wireless device circuit section 5 has a display means 6 such as a liquid crystal panel for displaying information of the portable wireless device, and is arranged outside the conductor plates 1a and 1b and in parallel with the two conductor plates. Since there is no conductor that blocks between the conductor plates 1a and 1b, the antenna is in an ideal state and a large antenna gain can be obtained.

In the present invention, the slot antenna mode and the loop antenna mode are used, but both are magnetic field detection type antennas. Since the electromagnetic field distribution near the human body tends to have a strong magnetic field component and a small electric field component, when the portable wireless device of the present invention is worn on a human body or clothes in a portable state, the antenna characteristics are further improved as compared with a single body. This has the effect of improving the sensitivity of the wireless device.

(Embodiment 2) FIG. 2 is a schematic perspective view of a portable radio device according to an embodiment of the present invention. A short-circuit plate 10 connecting the two rectangular conductor plates 9a and 9b, and a tuning capacitive element 1 loaded between the conductor plates 9a and 9b on the opposite side of the short-circuit plate.
1 is arranged in the vicinity of the diagonal position on the conductor plates 9a and 9b. With such a positional arrangement of the short-circuit plate 10 and the capacitive element 11, the substantial opening area of the loop portion on the side surface can be secured as large as possible, the characteristics of the loop antenna can be improved, and the antenna dimension does not change. Nevertheless, the maximum antenna gain can be obtained. Also,
If there is no electrical influence, the outer sides of the conductor plates 9a and 9b and the outer side of the radio circuit section 12 may be covered with a plastic member or the like in order to improve the appearance.

The radio circuit section 12 includes the feeder lines 14a, 14
The conductor plates 9a, 9b and 15a, 15b are connected to each other at the feeding points via b. Also in this example, the feeding points 15a and 15b on the two conductor plates 9a and 9b are displaced from the position where the capacitive element 11 is loaded. The wireless device circuit section 12 includes display means 13 such as a liquid crystal panel for displaying information of the portable wireless device, and a conductor plate 9a,
Since the conductors 9a and 9b are arranged parallel to each other on the outside of 9b and are parallel to the two conductor plates, a larger antenna gain can be secured.

(Embodiment 3) FIG. 3 is a schematic perspective view of a portable radio device according to an embodiment of the present invention. Two conductor plates 17a,
17b are placed substantially in parallel with a gap. Although the conductor plate 17a and the conductor plate 17b are depicted separately in this figure for the sake of explanation, they are actually connected by a short-circuit plate 18 at the end. Further, if there is no electrical influence, the outer sides of the conductor plates 17a and 17b may be covered with a plastic member or the like in order to improve the appearance. Capacitance elements 19 loaded on the ends of the conductor plates 17a and 17b and on the opposite side of the short-circuit plate 18 are for tuning to a desired frequency and are ceramic capacitors or the like.

The radio device circuit section 20 includes power supply lines 22a and 22a.
The conductor plates 17a, 17b and 23a, 23b are connected to each other at the feeding points via b. Two conductor plates 17
The feeding points 23a and 23b on a and 17b are connected to the capacitive element 19
The configuration is shifted from the loaded position.

The radio circuit section 20 has a display means 21 such as a liquid crystal panel and is formed between the conductor plates 17a and 17b. In such a configuration, the space inside the portable wireless device including the antenna device can be effectively used, and the size of the entire device can be reduced. A cutout portion (hereinafter referred to as a window) 24 is provided at a position where the conductor plates 17a and 17b overlap the radio circuit.
a and 24b are configured, and in order to make it possible to confirm the display content of the display means 21 on the upper conductor plate 17a from the outside, the lower conductor plate 17b is replaced with a battery (not shown) of the portable radio device. The purpose is to facilitate. In the case of a structure in which the battery is replaced from the side, the window of 24b may be omitted and only the window of 24a may be provided. Also, this window 24
By providing a and 24b, conductor plates 17a and 17b
And the radio circuit section 20 can be set to a large distance,
It also has a role of reducing the amount of noise generated by the radio device circuit section 20 that jumps into the antenna and obtaining good antenna characteristics. Therefore, this window is 24a, 24b
Is highly effective if it is provided near a local oscillator, a DC-DC converter, or the like that is apt to generate particularly large noise even in a radio device circuit.

(Embodiment 4) FIG. 4 is a schematic perspective view of a portable wireless device according to an embodiment of the present invention. The capacitive element 27 loaded between the two rectangular conductor plates 25a and 25b placed substantially in parallel includes the short-circuit plate 26 and the rectangular conductor plates 25a and 25b.
They are arranged near the diagonal position of 5b. By arranging the positions of the short-circuit plate 26 and the capacitive element 27 as described above, the substantial opening area of the loop portion on the side surface can be secured as large as possible, the characteristics of the loop antenna can be improved, and the antenna dimension does not change. Nevertheless, a larger antenna gain can be obtained. Power supply line 30a,
30b is connected to the conductor plates 25a and 25b and the feeding points of 31a and 31b, respectively. Also in this example, the positions of the feeding points 31a and 31b are displaced from the positions where the capacitive element 27 is loaded. Further, if there is no electrical influence, the outside of the conductor plates 25a and 25b may be covered with a plastic member or the like in order to improve the appearance.

A radio circuit section 28 having a display means 29 such as a liquid crystal panel is placed between the conductor plates 25a and 25b. In such a configuration, the space inside the portable wireless device including the antenna device can be effectively used, and the size of the entire device can be reduced.

Cutout portions (hereinafter referred to as windows) 32a and 32b are formed in the central portions of the conductor plates 25a and 25b.
The upper conductor plate 25a has the purpose of allowing the display contents of the display means 29 to be confirmed from the outside, and the lower conductor plate 25b has the purpose of facilitating the replacement of the battery (not shown) of the portable wireless device. . In the case of a structure in which the battery is replaced from the side, the window of 24b may not be provided and only the window of 24a may be used. Further, by providing the windows 32a and 32b, it is possible to increase the distance between the conductor plates 25a and 25b and the radio circuit section 28, and to reduce the amount of noise generated by the radio circuit section 28 entering the antenna. However, it also has a role of being able to obtain good antenna characteristics.

FIG. 5 is a block diagram showing an embodiment of the configuration of the portable wireless device of the present invention. In the figure, an antenna device 100 includes a receiving circuit 101 including an antenna matching circuit.
Connected with. The signal from the VCO 102 is applied to the receiving circuit unit 101 via the frequency synthesizer 103. The signal amplified and filtered by the reception circuit 101 is demodulated by the demodulation circuit 104, processed by decoding and the like by the signal processing circuit 105, and enters the CPU 106. CPU10
Reference numeral 6 indicates a display means 107 such as a liquid crystal panel by this signal,
The sounding means 108 such as a piezoelectric element or an electromagnetic buzzer is driven. There are also cases where audio signals are played through the speaker. Further, an input means 109 such as a switch is also connected to the CPU 106. Power is supplied to these components from the built-in battery.

In this example, the portable wireless device has an example of receiving function. However, the effect of the antenna device of the present invention and the portable wireless device equipped with the antenna device of the present invention are not changed even if the portable wireless device has a function of transmitting / receiving or transmitting only. .

[0029]

As described above, in the antenna device according to the present invention, the feeding point position on the two conductor plates is made different from the position where the tuning capacitive element is loaded.
This antenna device can be surely functioned as a slot antenna, and an antenna gain larger than that of a conventional loop antenna can be obtained. Further, by arbitrarily moving the feeding point position so that impedance matching between the radio circuit portion and the antenna portion can be easily achieved, the feeding impedance of the conductor plate at the feeding point can be arbitrarily adjusted.

Further, by disposing the short-circuit plate and the capacitive element in the vicinity of the diagonal position of the rectangular conductor plate, the loop antenna mode can be maximally utilized without enlarging the size of the portable radio device and a larger antenna gain can be obtained. Obtainable. Both the slot antenna and the loop antenna are magnetic field detection type antennas, and since the magnetic field component is large in the electromagnetic field distribution near the human body, the sensitivity of the wireless device is improved, making it suitable as an antenna device for portable wireless devices used near the human body. There is.

Further, according to the portable wireless device of the present invention, 2
Since the radio circuit section is formed between the conductor plates and the cutout (window) is provided in the conductor plate, the influence of noise from the radio circuit can be reduced, and the antenna characteristics are not impaired, and the radio main unit It is possible to configure a small portable wireless device that effectively utilizes the internal space.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a first embodiment of a portable wireless device including an antenna device of the present invention.

FIG. 2 is a schematic perspective view showing a second embodiment of a portable wireless device provided with the antenna device of the present invention.

FIG. 3 is a schematic perspective view showing a third embodiment of a mobile wireless device provided with the antenna device of the present invention.

FIG. 4 is a schematic perspective view showing a fourth embodiment of a portable wireless device provided with the antenna device of the present invention.

FIG. 5 is a block diagram showing an embodiment of the configuration of the portable wireless device of the present invention.

FIG. 6 is a graph showing the antenna radiation directivity of the antenna device of the present invention and a conventional example.

7A and 7B are diagrams for showing the antenna characteristics depending on the arrangement position of the capacitive element, wherein FIG. 7A is a plan view of the antenna device and FIG. 7B is a side view thereof.

FIG. 8 is a view for explaining the action of the present invention,
(A) is a plan view of an antenna device according to the present invention,
(B) is the side view.

[Explanation of symbols]

 2 Gap 1a, 9a, 17a, 25a, 111a Conductor plate 1b, 9b, 17b, 25b, 111b Conductor plate 3, 10, 18, 26, 112 Short-circuit plate 4, 11, 19, 27, 113 Capacitive element 5, 12, 20, 28 Radio equipment circuit section 7a, 14a, 22a, 30a Feed line 7b, 14b, 22a, 30b Feed line 114 Magnetic field component 115 Loop opening 6, 13, 21, 31 Display means 8a, 15a, 23a, 31a Feed Points 8b, 15b, 23b, 31b Feeding points 24a, 32a Cutout parts (windows) 24b, 24b Cutout parts (windows) 100 Antenna device 101 Reception circuit 102 VCO 103 Frequency synthesizer 104 Demodulation circuit 105 Signal processing circuit 106 CPU 107 Display means 108 Sounding means 109 Input means 110 Antenna directivity of the present invention Constant results 111 antenna directivity measurement result of the conventional example

Claims (5)

[Claims] 1. Two placed in parallel with a gap between them
An antenna device having a single conductor plate, a short-circuit plate in which the conductor plates are short-circuited at the conductor plate end, and a capacitive element loaded at the conductor plate end opposite to the short-circuit plate, The antenna device, wherein the position of the feeding point on the conductor plate and the position where the capacitive element is loaded are different. 2. The antenna device according to claim 1, wherein the conductor plate has a quadrangular shape, and the short-circuit plate and the capacitive element are respectively disposed in the vicinity of diagonal positions of the conductor plate. 3. A portable wireless device comprising the antenna device according to claim 1. 4. The portable wireless device according to claim 3, wherein a circuit portion of the portable wireless device is formed between the two conductor plates. 5. The portable wireless device according to claim 4, wherein a cutout portion is provided in a portion of at least one of the conductor plates that overlaps with the portable wireless device circuit portion.