JP2001320222A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-sensitivity antenna device for a radio clock receiver. SOLUTION: A loop antenna ANT is constituted by winding an electric wire 4 around a frame 1, which is supported by a pedestal 2 connected with connection columns 3-1 and 3-2, so as to obtain the inductance of a prescribed size. An antenna tuner circuit is constituted by housing an external capacitor CT inside the pedestal 2 of the loop antenna ANT and electrically connecting the electric wire 4 of the loop antenna ANT to the external capacitor CT. Further, the antenna device is constituted by housing a receiving circuit high frequency stage RFC inside the pedestal 2 and electrically connecting the receiving circuit high frequency stage RFC to the loop antenna ANT and the external capacitor CT. In order to increase the inductance value of the loop antenna ANT, the number of times of winding the electric wire 4 is increased and the electric wire 4 is coated with a resin 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for a receiving device that handles signals in a long-wave region such as a radio clock receiving device, and more specifically, an antenna device in which a loop antenna and a receiving circuit high-frequency stage are modularized. It is about.

[0002]

2. Description of the Related Art At present, with the development of communication infrastructure, countless broadcast waves are allocated to various frequency bands. 1
For a radio clock time signal system whose introduction has been considered since the middle of 960, a carrier wave for transmitting the standard time signal is assigned a frequency in the long wave region (30 to 300 kHz). Currently, for this radio clock time signal system, the standard radio wave transmitting station has a carrier frequency of 40 kHz.
z, a standard time signal is broadcast at an effective transmission output of 10 kW.

[0003] There are various types of antennas for receiving radio waves. When receiving a radio signal in a long wave range handled by a radio-controlled timepiece receiver, a bar antenna is used as the antenna of the receiver. There were many things. The reason is that the bar antenna has the advantages of high sensitivity and a small size. But the bar antenna
Phenomena such as increasing the phase rotation of the signal at the input stage of the receiving circuit and narrowing the frequency band of the received radio wave are likely to occur. For this reason, there has been a problem that handling is relatively difficult and the design of the receiving circuit is difficult.

[0004] In addition to a bar antenna, for example, a loop antenna or the like may be used for receiving a radio wave signal in a long wave region. If the loop radius of the loop antenna is set to 0.1 times or less the wavelength of the radio wave to be received, the current distribution on the electric wire is substantially constant. Therefore, the loop antenna is exclusively used as a converter for converting a radio signal into a current. In a general loop antenna, the electric wire is usually wound only for a few turns to a few tens turns. Therefore, the loop antenna has a low impedance (several tens to several hundreds of ohms), and is generally used in combination with the tuning transformer T as shown in FIG.

[0005]

SUMMARY OF THE INVENTION A radio-controlled timepiece receiver comprises:
It is used in combination with electronic devices and home appliances that use time information. For this reason, the radio-controlled timepiece receiver is basically installed indoors together with electronic devices and home electric appliances. Therefore, it is necessary that the antenna used in the radio timepiece receiver has high sensitivity. Of the antennas introduced above, the bar antenna is perfect in that it has high sensitivity. However, a radio-controlled timepiece that is installed together with an electronic device or a home appliance in a limited indoor space is not always installed in a location or an orientation that is convenient for receiving a radio signal by a bar antenna. Under such circumstances, the directivity of the bar antenna is a disadvantage,
Depending on the situation, a sufficient receiving sensitivity cannot be obtained, and rather, only a difficult-to-handle surface appears.

With respect to the loop antenna, which is another antenna introduced above, the receiving sensitivity may be slightly reduced depending on the installation location and orientation of the radio-controlled timepiece receiver, but since the directivity thereof is low, the installation location is low. The degree of freedom of orientation is high. Moreover, there is an advantage that handling is easy in terms of phase rotation and frequency band. However, the loop antenna is definitely less sensitive than the bar antenna. For this reason, the antenna of the radio-controlled timepiece receiver cannot be used especially indoors as it is in the conventional form. Accordingly, an object of the present invention is to provide an antenna device having high sensitivity by improving an antenna and an antenna circuit using a loop antenna as a basic structure.

[0007]

An antenna apparatus according to the present invention for solving the above-mentioned problems includes a loop antenna having a predetermined inductance, an external capacitive element which forms a tuning circuit together with the loop antenna, and a near-loop antenna. And a receiving circuit high-frequency stage arranged.
Here, the loop antenna includes a frame, a winding wound around the frame, a pedestal supporting the frame, and two connecting columns connecting the frame and the pedestal so as to sandwich the frame. The receiving circuit high-frequency stage is housed inside the pedestal.
Then, a resin mixed with a magnetic powder is applied around or partially around the winding wound around the frame.
Further, a partition is provided in a slot of the frame on which the electric wire is wound, and the electric wire is divided into a plurality of positions and wound on the frame.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A loop antenna is constructed by winding an electric wire around a frame supported by a pedestal joined by connecting columns so as to obtain an inductance of a predetermined size. An external tuning element is placed inside the pedestal of the loop antenna or in the gap between the two connecting columns extending to the inside of the opening of the frame, and the electric wire of the loop antenna is connected to the external tuning element to tune the antenna tuning circuit. Is configured. A high-frequency receiving circuit stage is housed inside the base of the loop antenna, and the high-frequency receiving circuit stage is electrically connected to the loop antenna and an external capacitive element to form an antenna device.

[0009] A resin mixed with magnetic powder is applied on the winding wound around the frame to improve the inductance value of the loop antenna. Further, the electric wire is divided into a plurality of positions and wound by a partition provided in the slot to reduce the stray capacitance. Additionally, a low-pass filter is housed inside the pedestal of the loop antenna, and this low-pass filter is connected between the external capacitive element and the high-frequency stage of the receiving circuit to prevent a reduction in noise resistance. Note that the low-pass filter is configured by, for example, a lead inductance component and a capacitance element.

[0010]

1 and 2 show a first embodiment of an antenna device according to the present invention, which can increase the sensitivity. 1 shows an external view and a partial cross-sectional view of the antenna device, and FIG. 2 is a system block diagram of the antenna device. First, in FIG. 1, a frame 1, a pedestal 2 for supporting the frame 1,
Two connecting columns 3-1 for connecting the frame 1 and the pedestal 2;
3-2 prepares a resin molded integrally. Here, as shown in the AA cross-sectional view in FIG. 1, the electric wires 4 are sequentially wound around the slots 7 of the frame body 1 to form a loop antenna ANT. Then, the external capacitive element CT is housed in the pedestal 2, and the electric wire 4 of the loop antenna ANT and the capacitive element CT are connected by the lead 5. Further, the receiving circuit high-frequency stage RFC is housed in the pedestal 2 and the electric wire 4
In addition, the antenna element of the present invention is configured by electrically connecting the capacitive element CT and the receiving circuit high-frequency stage RFC.

The system configuration of the antenna device shown in FIG. 1 is as shown in FIG. 2, and a tuning circuit is constituted by the loop antenna ANT and the external capacitance element CT. Actually, a variable capacitor CV for adjusting the tuning frequency is also connected in addition to the external capacitor CT, and this variable capacitor CV is also included in the tuning circuit. As for the variable capacitance element CV, for example, the reception circuit high-frequency stage RF
C is mounted on the configured substrate. Conventional loop antennas have low impedance, for example, several tens of ohms, for use as a current source based on radio signals.
~ Several hundred ohms. Therefore, the number of turns of the electric wire is small, and the inductance is small.

However, in the present invention, unlike the conventional loop antenna, the electric wire 4 is used to increase the sensitivity of the antenna device.
The number of times of winding around the frame 1 is increased. Then, the inductance value of the loop antenna ANT is increased, and a tuning circuit is configured by the loop antenna ANT and the external capacitance element CT. By increasing the number of windings of the electric wire 4, the sensitivity of the loop antenna ANT can be increased. As the number of windings of the electric wire 4 increases, the inductance and impedance of the loop antenna ANT increase. Therefore, in the present invention, the loop antenna ANT itself is used as a lumped constant type inductor of the tuning circuit, and the input / output between the tuning circuit and the receiving circuit can be achieved without using a tuning transformer by utilizing the high impedance of the loop antenna ANT. The impedance is matched.

In order to use the loop antenna ANT as a lumped-constant type inductor, it is desirable to increase its inductance value and, on the contrary, to minimize the stray capacitance as much as possible. Therefore, first, as shown in FIG.
Resin 6 mixed with magnetic powder on electric wire 4 wound around
Is applied. When the resin 6 is applied on the electric wire 4 as described above, the apparent magnetic permeability around the electric wire 4 wound around the frame 1 is increased by the magnetic powder mixed therein,
The inductance value of the loop antenna ANT can be increased without increasing the number of windings of the electric wire 4. This can increase the inductance value without increasing the DC resistance, which also contributes to increasing the Q of the tuning circuit.

Next, the electric wire 4 is formed in a laminated form in which the circumferential direction is lengthened, and the pedestal 2 of the loop antenna ANT accommodates the external capacitive element CT and the receiving circuit high-frequency stage RFC. When forming an inductor by winding an electric wire, if the electric wire 4 is wound around the frame 1 having the narrow slot 7 and its lamination form is a flat shape in which the circumferential direction is longer than the axial direction, the wire The average distance between them becomes longer, and the stray capacitance can be reduced. Also, loop antenna A
By arranging the NT, the external capacitance element CT, and the receiving circuit high-frequency stage RFC at positions adjacent to each other, the total length of the lead wires required to connect them can be shortened, and the stray capacitance can be reduced. Can be. These measures make it possible to use the loop antenna ANT as a lumped constant type inductor by increasing the inductance value and conversely reducing the stray capacitance.

A high impedance loop antenna AN
Using T makes it more susceptible to noisy radio waves,
There is a problem that the generation of electromagnetic noise increases. In order to suppress the generation of the electromagnetic wave noise as much as possible, it is effective to eliminate the portion that receives the noise radio wave as much as possible and to shield the lead wire and the like. As described above, if the loop antenna ANT, the external capacitive element CT, and the receiving circuit high-frequency stage RFC are arranged close to each other, the lead wires required to connect them can be shortened, and the electromagnetic wave noise can be reduced. Can hardly occur. It is desirable that the lead 5 shown in the embodiment of FIG. 1 be shielded.

Loop antenna ANT and external capacitive element C
The received signal that has passed through the tuning circuit constituted by T is
It is input to the receiving circuit high-frequency stage RFC. As shown in FIG. 2, the reception signal input to the reception circuit high-frequency stage RFC is:
After being subjected to amplitude amplification and filtering processes several times in the plurality of amplifiers AMP and the filter FIL, they are detected by the detection circuit DET. The detected reception signal is supplied to a differentiating circuit DIFF and a flip-flop circuit F. F. Is shaped into a square wave and output from the DATA terminal in the form of a digital signal. This digital signal is supplied to, for example, a radio-controlled timepiece receiving device that is configured separately from the antenna device.
In addition, REG shown in FIG.
Is a regulator circuit that supplies a voltage for operating each unit circuit that constitutes the circuit.

In realizing the antenna device according to the present invention shown in FIGS.
Using a polyurethane wire of about 115
It was wound around. At this time, the impedance of the loop antenna ANT is about 50 kΩ. Note that a resin mixed with ferrite powder is applied on the electric wire wound around the frame. It has been confirmed that the application of the resin containing the ferrite powder can increase the inductance value of the loop antenna by about 10%. Since the Q value of the loop antenna ANT itself is low, a trimmer capacitor having a Q value as high as possible is used as the external capacitance element CT.

In the antenna device configured as described above, it is possible to realize reception sensitivity comparable to that of a ferrite bar antenna. In addition, since the loop antenna is used, the phase rotation is smaller than that of the bar antenna, the frequency band is widened, and the handling is easy. And since the antenna device is modularized, the degree of freedom of the installation location and orientation of the antenna is improved, and in combination with the directivity characteristic, sufficient reception sensitivity is ensured even in indoor use where the radio signal is weak. It has become possible.

By the way, in order to reduce the stray capacitance generated in the loop antenna ANT, as shown in the sectional view taken along the line AA in FIG. Is desirable. However, if such a configuration is used unconditionally, there is a problem that the size of the loop antenna ANT increases. Therefore, when the number of windings of the electric wire 4 around the frame 1 is increased, as shown in FIG.
Is provided with a partition 8 inside. Partition 8 as shown in FIG.
Is provided, the distance between the electric wires wound around the slots 7 on both sides of the partition 8 is increased. As a result, the average distance between the wires 4 is increased, and an increase in stray capacitance is prevented.
Further, since the number of electric wires 4 stacked in the circumferential direction can be reduced, it is possible to prevent the loop antenna ANT from being enlarged.

FIG. 4 shows a second embodiment of the present invention.
In the antenna device shown in FIG. 4, the tips of two connection columns 3-1 and 3-2 for connecting the frame 1 and the pedestal 2 extend to the inside of the opening of the frame 1. A space is formed between the connecting columns 3-1 and 3-2, as shown in the section BB in FIG. 4, and the external capacitive element CT is accommodated in this space. Also, a lead 5 is provided between the connecting pillars 3-1 and 3-2 and the frame 1.
a, slits for passing 5b are provided. A low-pass filter LPF is provided in an empty space in the pedestal 2, and the loop antenna ANT, the external capacitive element CT, the low-pass filter LPF, and the receiving circuit high-frequency stage RFC are electrically connected to each other. Is different.

In the configuration of FIG. 4, the loop antenna AN
There is an advantage that the physical distance between T and the external capacitance element CT can be reduced, and the connection and wiring of the lead 5a for connecting the loop antenna ANT and the external capacitance element CT are facilitated. Then, the newly provided low-pass filter LP
F functions to prevent the noise from entering the receiving circuit high-frequency stage RFC, in contrast to the fact that the antenna device is easily affected by noise due to the increase in impedance. The low-pass filter LPF utilizes an inductance component appearing in the lead 5b,
The lead 5b and a capacitor may be used in combination. The structure of the antenna device of FIG. 4 other than the above is basically the same as that of the antenna device of FIG. 1, and the obtained effects are the same.

[0022]

As described above, the antenna device according to the present invention increases the inductance value of the loop antenna by taking measures such as increasing the number of windings. As a result, the reception sensitivity as an antenna is increased, and at the same time, the loop antenna is used as a lumped constant type inductor. A tuned circuit is constituted by the loop antenna as the lumped constant type inductor and an external capacitive element, and a signal is inputted from the tuned circuit to a high-frequency stage of a receiving circuit arranged near the tuned circuit. With this configuration, it is possible to obtain an antenna device that has a small phase rotation, a wide frequency band, and is easy to handle, while obtaining reception sensitivity equivalent to that of a ferrite bar antenna.

This antenna device is modularized by accommodating an external capacitive element and a receiving circuit high-frequency stage in a pedestal. As a result, the degree of freedom of the installation location and orientation of the antenna is improved, and in combination with the directivity of the loop antenna structure, sufficient reception sensitivity can be ensured even when used indoors where the radio signal is weak. Additionally, by configuring a low-pass filter with the inductance component of the lead wire and the capacitive element, it is possible to prevent noise from entering the antenna device which is easily affected by noise due to the high impedance.

[Brief description of the drawings]

FIG. 1 is an external view of an antenna device according to a first embodiment of the present invention.

FIG. 2 is a system block diagram of the antenna device shown in FIG. 1;

FIG. 3 is a cross-sectional view of the frame when a partition is provided in the slot.

FIG. 4 is an external view of an antenna device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a usage form of a conventional loop antenna.

[Explanation of symbols]

1: frame 2: pedestal 3-1 and 3-2: connecting pillar
4: Electric wire 5, 5a: Lead 5b: Lead whose inductance component is used for a low-pass filter 6: Resin containing magnetic powder 7: Slot 8: Partition ANT: Loop antenna CT: External capacitance element LPF: Low-pass filter RFC: Receiving Circuit high frequency stage

Continuation of the front page (72) Inventor Yasuyuki Ueki 18 Gomigaya, Tsurugashima-shi, Saitama Toko F-term in Saitama Works (reference) 5J046 AA02 AA03 AA12 AB00 AB11 QA02 QA09 QA10

Claims (9)

[Claims] 1. An antenna comprising: a loop antenna having a predetermined inductance; an external capacitive element forming a tuning circuit together with the loop antenna; and a receiving circuit high-frequency stage disposed close to the loop antenna. apparatus. 2. The loop antenna, comprising: a frame; a winding wound around the frame; a pedestal for supporting the frame;
2. The antenna device according to claim 1, comprising: two connection columns connecting the frame and the pedestal so as to sandwich the frame. 3. The antenna device according to claim 2, wherein the external capacitive element and the high-frequency receiving circuit are housed inside the pedestal. 4. The two connecting columns extend to the inside of the opening of the frame body, and an external capacitive element is housed in a gap formed between the connecting columns inside the opening, 3. The antenna device according to claim 2, wherein the receiving circuit high-frequency stage is housed inside a pedestal. 5. The frame body is provided with a partition in a slot in which the electric wire is wound, and the electric wire is divided and wound at a plurality of positions by the partition. The antenna device according to any one of claims 2 to 4. 6. The loop antenna according to claim 2, wherein a resin mixed with a magnetic powder is applied around or partially around the winding wound around the frame. The antenna device according to claim 5. 7. The antenna device according to claim 2, wherein a low-pass filter is housed inside the pedestal. 8. The antenna device according to claim 7, wherein the low-pass filter includes an inductance component and a capacitance element appearing in a lead wire connected to the external capacitance element. 9. The antenna device according to claim 1, wherein the antenna device is used for a radio-controlled timepiece receiver.