JP3046233B2 - Thin receiver and transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin receiving device or transmitting device.

[0002]

[Prior art]

Conventional technology 1. FIG. 14 shows, for example, HAM Journa.
l October 1994, page 50, or the IEICE Transactions Vol. 71-BN
O. FIG. 11 is an external view of a pager loop antenna described in page 11208 of 11NOVEMBER. In FIG. 14, 1 is a housing, 2 'is a loop antenna provided on the side surface of the housing 1, 3 is a transmitting / receiving circuit for transmitting and receiving radio waves using this loop antenna 2', and 11 is a loop antenna 2 ' This is a capacitor inserted in series.

FIG. 15 is a plan view when the pager loop antenna 2 'shown in FIG. 14 is developed on a plane.
15, the same reference numerals as those in FIG. 14 denote the same or corresponding parts, and reference numerals 31 and 32 denote connection tap positions which are connection points between connection lines extending from the transmission / reception circuit 3 and the loop antenna 2 '. . FIG. 16 is an electrical equivalent circuit of FIG. In FIG. 16, the same reference numerals as those in FIG. 15 indicate the same or corresponding parts.

Next, the operation will be described with reference to an electrical equivalent circuit diagram 16 of the loop antenna 2 '. According to the shape of the loop antenna, the constituent conductor material, and the shape, the loop antenna 2 ′ has inductances L ₁ and L ₂ , and a circuit resistance R that is a series resistance of a radiation resistance and a radiation resistance composed of a DC loss and a high-frequency loss. , The input impedance Z of the transmitting and receiving circuit 3
The current I I = E ₀ / [Z ₁ + Z ₂ 〃Z i + Z c + R] obtained from the induced voltage E ₀ due to the received radio wave and the series combined impedance of the loop antenna 2 ′ circuit includes the combined impedance of i and the impedance Z ₂ of the inductance L ₂ . Equation 1) flows. Here, Z ₁ is the impedance of the inductance L1, Zc is the impedance of the capacitor 11. Further, in this specification, the symbol “を” represents an operation for obtaining a combined resistance of impedances connected in parallel, and Za〃Zb = (Za · Zb) / (Za + Zb).

[0005] The impedance Z ₂ 〃Zi parallel-connected part of the input impedance Zi of the impedance Z ₂ and receiving circuit 3 due to the inductance L ₂ is Z ₂ 〃Zi = Z ₂ '+ Zi' (Equation 2) and serial-parallel Can be converted. Here, Z ₂ ′ and Zi ′ are Z ₂ , Zi
Are serial-to-parallel converted impedances.

At the resonance frequency fr of the pager loop antenna, the inductances L ₁ and L ₂ , the capacitor 11
Since the impedances Z ₁ , Z ₂ , and Zc are zero,
(Equation 1) is _{i = E 0 / [Zi '} + R] , and the electric power to the maximum can be transmitted.

[0007] _{Here, Zi '= [| Z 2} | 2 / (Zi 2 + | Z 2 | 2)] and is, Zi' since reactance component of can be determined by the value of inductor L _2, a transceiver circuit 3 Of the reactance component at the resonance frequency fr can be adjusted at the connection tap position. Specifically, the reactance component at the connection tap position is adjusted so as to cancel the reactance component at the resonance frequency fr.

[0008] With the above configuration, FIG.
Instead of a pager shape as shown by, the thickness is, for example,
When the card size is about 1 to 3 mm, if the loop antenna 2 'is held by the human body, especially by hand, the stray capacitance causes the inductor to decrease apparently, and it becomes impossible to resonate at the specified frequency, and the circuit current decreases. Disadvantages occur.

[0009] 2. Prior art As a conventional loop antenna configuration for solving such a drawback, Japanese Patent Publication No. 5-246 is known.
There is a construction method disclosed in Japanese Patent No. 93. FIG. 17, 1
8 and 19 are views for explaining a conventional loop antenna disclosed in Japanese Patent Publication No. 5-24693, FIG. 17 is a perspective view showing an appearance of a loop antenna 2 'formed in a card shape, and FIG. FIG. 19 is a cross-sectional view of the loop antenna 2 ′ as viewed from the side, and FIG. 19 is an electrical equivalent circuit of the loop antenna 2 ′. 17 to 19, the same reference numerals as those in FIG. 14 represent the same or corresponding parts, and reference numerals 21 to 24 in FIG.
Are the upper sheet metal part 21 'and the slotted side sheet metal part 2 of the card-shaped loop antenna 2' shown in FIG.
An equivalent electric element expressed by an inductor and a loss resistance in each of the 2 ′, the bottom sheet metal part 23 ′ and the bent side sheet metal part 24 ′, and 220 is a capacitor mainly generated in the slit part 220 ′.

Next, the operation will be described. The operation is shown in FIG.
14 is different from the case of FIG. 14 in that the loop antenna 2 ′ is formed of a wide U-shaped sheet metal, and thus has a characteristic that resonance frequency fluctuation due to the influence of the human body is small. The reason is that the capacitor generated in the slit portion is sufficiently larger than the floating capacitor generated by the human body when holding the card.

However, when the thickness is reduced, the loop area [U-shaped cross-sectional area] decreases, and there is a drawback that the induced voltage E ₀ cannot be obtained.

Conventional technique 3. Further, as an example in which the fluctuation of the resonance frequency caused by the influence of the human body can be suppressed, there is a configuration method disclosed in Japanese Patent Publication No. 4-6123. 20 and 21 show a conventional loop antenna disclosed in Japanese Patent Publication No. 4-6123, FIG. 20 is a diagram showing the configuration of this loop antenna, and FIG. 21 is an electrical equivalent circuit of the loop antenna shown in FIG. . 20 and 21, the same reference numerals as those in FIG. 14 indicate the same or corresponding parts. However,
The loop antenna 2 'is made of a material having a large relative permittivity. 21A to 21N are equivalent electric elements represented by distributed inductors, capacitors, and loss resistances conforming to the shape of the high dielectric loop antenna 2 '.

Next, the operation will be described. The operation is the same as that of FIG. 14, but unlike the case of FIG. 14, the resonance frequency of the loop antenna 2 ′ is determined by the capacitance and the internal inductor determined by the relative permittivity of the high dielectric substance and the dimensions of the loop.
Since this loop antenna 2 'uses a high dielectric material, it has a feature that resonance frequency fluctuation due to the influence of the human body is small. That is, the resonance frequency fr is

[0014]

(Equation 1)

(Where ε ₀ is the dielectric constant of a vacuum, εr is the relative dielectric constant of the loop antenna 2 ′, and d is the loop dielectric 2 ′
The radius of the cross section, μ ₀ is the magnetic permeability of vacuum, μ _s is the relative magnetic permeability of the loop antenna 2 ′, and D is the radius of the circle of the loop antenna 2 ′. Therefore, if the relative magnetic permeability _μs is large, even if the radius D of the loop antenna 2 ′ becomes small by hand, the fluctuation of the resonance frequency is small.

However, in general, a material such as ceramic is used for the high dielectric substance, and has a disadvantage that it is difficult to realize a thin card shape because it is hard and easily broken.

[0017]

Some of the above-mentioned conventional transmitting / receiving apparatuses have the following problems in realizing a thin transmitting / receiving apparatus such as a card. First, there is a problem that the resonance frequency changes easily due to the influence of the human body. Second, if the housing is made thin, there is a problem that a loop area cannot be obtained and a sufficient induced current cannot be obtained. Third, since the material of the antenna is hard and easily broken, it cannot cope with distortion (bending, twisting, etc.) of the shape, and also in terms of material and manufacturing, it is possible to reduce the cost required for a thin transceiver. There was a problem that it was not possible.

The present invention has been made to solve the above-mentioned problems. The first object is to reduce the influence of the human body, and the second object is to satisfy thin shapes. The purpose of the present invention is to realize a thin transmitting / receiving device.

[0019]

In a thin transmitting device and a thin receiving device according to the present invention, a thin housing containing a receiver, a radio wave received in the housing and connected to the receiver. A loop antenna and a predetermined point on the loop antenna are defined as stray capacitance connection points, and the loop antenna between the stray capacitance connection points is inserted in series with the loop antenna.
A capacitive reactance element having a capacitance set so as to resonate at the reception frequency of the loop antenna .

Here, for example, a capacitor can be used as the capacitive reactance element, and a point having a high possibility of generating a stray capacitance is selected between predetermined points.

A thin housing in which a receiver is built, a portion in the housing for receiving radio waves and connected to the receiver and having a long distance to an outer frame of the housing; The loop antenna having a plurality of portions where the distance is relatively short, and the plurality of short portions each serving as a stray capacitance connection point. The stray capacitance connection point is inserted in series with the loop antenna between these stray capacitance connection points. And a capacitive reactance element whose capacitance is set so as to resonate at the reception frequency of the loop antenna .

Here, as the capacitive reactance element, for example, a capacitor can be used. The outer frame of the housing
The outer wall of the housing touched by the human body, and particularly refers to the side surface of the thin housing when the surface having the largest area in the thin housing is the upper surface or the lower surface. The reception frequency of the loop antenna is selected within the frequency band of the radio wave to be received. Also,
The long part is a part where the distance to the outer frame of the housing is longer than the short part. Therefore, the loop antenna is configured such that the distance to the outside of the housing changes in each part.

A thin housing having a built-in receiver, a portion inside the housing for receiving radio waves and connected to the receiver and having a long distance to an outer frame of the housing; The loop antenna having a plurality of portions where the distance is relatively short, and the plurality of short portions each serving as a stray capacitance connection point. The stray capacitance connection point is inserted in series with the loop antenna between these stray capacitance connection points. And a capacitive reactance element whose capacitance is set so as to resonate at the reception frequency of the loop antenna .

Here, the midpoint is the midpoint of the length of the loop antenna between the stray capacitance connection points.

The loop antenna is constituted by a polygon having a vertex disposed near the outer frame of the housing and a vertex disposed far away, and the capacitive reactance element is disposed far from the housing. The loop antenna is inserted between the vertices that are
The capacitance is set so as to resonate at the receiving frequency of the antenna.

Here, the vertices arranged in the vicinity of the housing represent the stray capacitance connection points of claim 1 or 2, and the vertices serving as these stray capacitance connection points and the element on which the capacitive reactance element is arranged. Are alternately arranged on the loop antenna.

[0027] The invention is characterized in that the casing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape.

[0028] A thin housing containing a receiver, a substrate built in the housing, and a first loop antenna disposed on one surface of the substrate and connected to the transmitter for receiving radio waves. A second loop antenna disposed on the other surface of the substrate and connected to the transmitter to receive a radio wave; a first plate-shaped conductor provided on the first loop antenna; And a second plate-shaped conductor provided on the second loop antenna and opposed to the first plate-shaped conductor so as to generate a capacitance between the loop antenna and the first plate-shaped conductor. It is.

A thin housing containing a transmitter, a loop antenna in the housing for transmitting radio waves and connected to the transmitter, and floating between two predetermined points on the loop antenna. Between the capacitance connection points and inserted in series with the loop antenna between the stray capacitance connection points, and the loop antenna
And a capacitive reactance element having a capacitance set so as to resonate at a transmission frequency of

Here, as the capacitive reactance element, for example, a capacitor can be used.

A thin housing containing a transmitter, a portion inside the housing for transmitting radio waves and being connected to the transmitter and having a long distance to an outer frame of the housing; The loop antenna having a plurality of portions where the distance is relatively short, and the plurality of short portions each serving as a stray capacitance connection point. The stray capacitance connection point is inserted in series with the loop antenna between these stray capacitance connection points. And a capacitive reactance element whose capacitance is set so as to resonate at the transmission frequency of the loop antenna .

Here, as the capacitive reactance element, for example, a capacitor can be used. The outer frame of the housing
The outer wall of the housing touched by the human body, and particularly refers to the side surface of the thin housing when the surface having the largest area in the thin housing is the upper surface or the lower surface. The transmission frequency of the loop antenna is selected within the frequency band of the radio wave to be transmitted. Also,
The long part is a part where the distance to the outer frame of the housing is longer than the short part. Therefore, the loop antenna is configured such that the distance to the outside of the housing changes in each part.

The above-mentioned capacitive reactance element is inserted in series with the above-mentioned loop antenna between the above-mentioned stray capacitance connection points, and the insertion position is a midpoint between the above-mentioned stray capacitance connection points. is there.

Here, the midpoint is the midpoint of the length of the loop antenna between the stray capacitance connection points.

The loop antenna is constituted by a polygon having a vertex arranged near the outer frame of the housing and a vertex arranged far away, and the capacitive reactance element is arranged far from the housing. The loop antenna is inserted between the vertices that are
The capacitance is set so as to resonate at the transmission frequency of the antenna.

Here, the vertices arranged in the vicinity of the housing represent the stray capacitance connection points according to claim 7 or 8, and the vertices serving as these stray capacitance connection points and the element on which the capacitive reactance element is disposed. Are alternately arranged on the loop antenna.

[0037] The invention is characterized in that the casing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape.

[0038] A thin case containing a transmitter, a substrate contained in the case, and a first loop antenna disposed on one surface of the substrate and connected to the transmitter for transmitting radio waves. A second loop antenna disposed on the other surface of the substrate and connected to the transmitter to transmit a radio wave; a first plate-shaped conductor provided on the first loop antenna; And a second plate-shaped conductor provided on the second loop antenna and opposed to the first plate-shaped conductor so as to generate a capacitance between the loop antenna and the first plate-shaped conductor. It is.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of a card-shaped transmitting / receiving device according to an embodiment of the present invention, in which a built-in loop antenna and a transmitting / receiving circuit are shown so as to be visible through the upper surface of a housing. . In FIG. 1, 1 is a card-shaped casing, 2 is a rectangular loop conductor provided on a substrate housed in the card-shaped casing 1, and four vertexes of this rectangle are denoted by A to D, respectively. It is indicated by reference numerals. Therefore, each side of the loop conductor 2 is each of the four sides sandwiched between the vertices. A transmission / reception circuit 3 is connected to the loop conductor 2 and receives a radio wave received by the loop conductor 2 and transmits a radio wave via the loop conductor 2. It is a provided capacitor. 31 and 32 are connection lines connecting the loop conductor 2 and the transmission / reception circuit 3.

FIG. 2 is an electrical equivalent circuit of the card transmitting / receiving apparatus shown in FIG. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Reference numerals 210 to 241 denote equivalent electric elements of the loop conductor 2 located on both sides of the capacitors 11 to 14 disposed at the center of each side, respectively.
0 is a loss resistance and an inductive reactance generated between the capacitor 11 and the vertex D; similarly, 211 is the capacitor 11 and the vertex A; 220 is the capacitor 12 and the vertex A;
21 is the capacitor 12 and the vertex B, 230 is the capacitor 1
3 and vertex B, 231 are connected to capacitor 13 and vertex C, 240
Indicates a loss resistance and an inductance generated between the capacitor 14 and the vertex D.

FIG. 3 is an electric equivalent circuit in which the loop conductor 2 is represented using an equivalent electric element for each side. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. 2
Reference numeral 1 denotes an electrical equivalent element obtained by combining two sets of loss resistance and inductance indicated by reference numerals 210 and 211 in FIG. Similarly, 22 is 220 and 221, 23 is 230 and 23
1 and 24 are two sets of loss resistances represented by 240 and 241.
An electrical equivalent element represented by a set of loss resistance and inductive reactance by combining inductances.

FIG. 4 is an external view when the card-shaped casing 1 is held by hand, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Reference numeral 9 denotes a user's hand, 15 is a stray capacitance generated between the hand 9 and the vertex A of the loop conductor 2, and 16 is a stray capacitance generated between the hand 9 and the vertex B. Since the user has a portion near both vertices AB of the rectangle as shown in FIG.
And a stray capacitance is generated. The location where the stray capacitance occurs varies depending on the position of the hand held by the user, but in actual use it is expected that it often has near the top of a rectangle as shown in FIG.

FIG. 5 is an electrical equivalent circuit of the card-shaped transmitting / receiving apparatus shown in FIG. 5, the same reference numerals as those in FIG. 3 denote the same or corresponding parts. 17 is FIG.
The stray capacitance Cst generated when the card-shaped housing 1 is held by hand as shown in FIG.

Next, the operation will be described. Resonant frequency of the loop conductor 2 is mainly defined by the capacitive reactance of the inductive reactance and capacitor 11 to 14 of the electrical equivalent elements 21 to 24 of FIG. 3, receive the resonant frequency of the loop conductor
Set signal frequency or transmission frequency, and the set co
It is designed so that the maximum current flows at the vibration frequency. Therefore, the capacitive reactance of the capacitor 11 and the like connected to the loop conductor 2 is one of the major factors that determine the resonance frequency. However, when the human hand 9 approaches the vicinity of the loop conductor 2, the stray capacitance Cst
Is generated, the state can not be able to fringe physician sufficient reception affect the resonance frequency, especially in the loop antenna of the card shape, the prior art has not been able to successfully solve the problem . According to the present invention for solving this problem, even if the stray capacitance Cst occurs, the resonance frequency is little affected, and a current close to the maximum can be obtained.

The basic idea of the first embodiment is that capacitors 11 to 1 are provided for each side of a polygonal loop conductor 2.
4 and the reception frequency or transmission frequency of the loop conductor 2
The point is that the capacitances of the capacitors 11 to 14 are set so as to resonate on each side at a wave number (hereinafter referred to as a designated resonance frequency). For example, between the vertices AB in FIG. 4, the capacitance of the capacitor 12 is set so as to resonate at the designated resonance frequency. This capacitance can be derived from the inductance 22 between the vertices AB. In this case, vertex A
-B, the inductance of the electric equivalent element 22 and the capacitor 12 resonate in series.
2, the largest current flows through the route, and is not affected by the stray capacitance Cst connected in parallel between the vertices A and B. Similarly, the capacitor capacity is set in the other sides, and the sides are designed to resonate at the same designated resonance frequency, so that the maximum current flows through the loop conductor 2 as a whole.

The operation will be described in detail below. Generally, when the length of the long side is a, the length of the short side is b, and the loop conductor 2 is a single wire having a diameter of 2r, the inductance L includes the mutual interference between the wires.

[0047]

(Equation 2)

Is represented by Here, each side length is a shape factor of d = [a ² + b ² ] ^1/2 and P = 1.75 to ^{2 in} cm.

From the above, the value of the inductance on each side is:
It can be considered that it is proportional to the length of each side. Here, the electrical equivalent elements 210, 211, 220, 221, 230, and 23
The inductances of 1, ₂₄₀ , and 241 are sequentially determined as L ₂₁₀ , L ₂₁₁ , L ₂₂₀ , L ₂₂₁ , L ₂₃₀ , L ₂₃₁ , L ₂₄₀ ,
_Assuming L ₂₄₁

[0050]

(Equation 3)

It can be considered as Therefore, when the card-shaped casing 1 is held by the hand 9, the capacitances of the capacitors 12 and 14 that make the impedance between the vertices AB and CD connected to the stray capacitance Cst zero at the designated resonance frequency fr. , C ₁₂ , C ₁₄ are

[0052]

(Equation 4)

Is as follows. Here, ωr = 2πfr. Similarly, when the input impedance of the transmitting and receiving circuit 3 is ignored and considered, the long side, that is, between the vertices A and D, BC
The capacitances C ₁₁ and C ₁₃ of the capacitors 11 and 12 between

[0054]

(Equation 5)

Is as follows. Further, if the input impedance Zi = Ri of the transmitting and receiving circuit, the parallel connection of Ri and C ₁₁ are parallel - converted by serial conversion equivalently in series element R
i ′ and C ₁₁ ′. Each element is

[0056]

(Equation 6)

Is as follows. Therefore, the capacitance C ₁ actually mounted at the position of C ₁₁ is

[0058]

(Equation 7)

From the above,

[0060]

(Equation 8)

Is obtained. From the above, the resonance current Ir flowing at the designated resonance frequency fr is

[0062]

(Equation 9)

Is obtained. Here, R is the electric equivalent element 21
-24, which is a combined resistance obtained by combining four loss resistances,
Since the two loss resistances are connected in series, the combined resistance can be easily obtained. Z _AB is the impedance generated by the inductive reactance between the vertices A and B. Similarly, Z _AD is between the vertices A and D, Z _BC is between the vertices B and C,
Z _CD is the impedance of the inductive reactance between the peaks C and D.

At this time, at the designated resonance frequency, Z _AB
Since it is set to = 0, it is not affected by the impedance of the stray capacitance. Further, since Z _BC = Z _AD = Z _CD = 0, the maximum current can flow through the loop conductor 2.

Therefore, regardless of the stray capacitance Cst generated when each of the vertices A to D is held by the hand 9, this stray capacitance Cst
Between the vertices A to D in a parallel connection relationship, a maximum current flows, and a decrease in transmission / reception sensitivity can be prevented.

Further, a capacitor constituting a resonance circuit is
Since there are multiple units corresponding to each side and each vertex, fine adjustment of the resonance frequency and correction of the temperature characteristics are easy, improving the degree of freedom in design, and variations in loop conductor performance in manufacturing.
This has the effect of making it easier to deal with.

Further, since the resonance circuit is configured in units of each side of the loop conductor, the capacitance value of the capacitor for facilitating the matching with the transmission / reception circuit can be freely set, and the number of parts of the matching circuit can be reduced. .

Embodiment 2 Embodiment 2 is an embodiment in which fluctuations in the resonance frequency can be suppressed more effectively by making the shape of the loop conductor rhombic.

FIG. 6 is a top view of the card-shaped transmitting / receiving apparatus according to the second embodiment. 6, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and 2a denotes a rhombic loop conductor configured such that each vertex is arranged near four sides of the rectangular card-shaped casing 1. The basic configuration of the second embodiment is the same as that of the first embodiment, and the basic operation and operation are also the same. Therefore, the features of the second embodiment will be described below.

In this loop conductor 2a, vertices A and B
Are arranged at positions near the long sides of the card-shaped casing 1. The reason is that there is a high possibility that large stray capacitances 15 and 16 are generated by the human hand 9 in the vicinity of each side of the card-shaped conductor 1, and the resonance frequency is generated at a location where such large stray capacitances 15 and 16 are generated This is because it is necessary to take a countermeasure to make the fluctuation less likely. That is, as shown in FIG. 6, the card-shaped transmission / reception device often holds each side of the card-shaped casing 1 so that the stray capacitances 15 and 16 generated by the hand 9 are connected to the hand 9 and the loop conductor. For two reasons, as the distance 1 of 2a becomes shorter, the resonance frequency tends to fluctuate due to the stray capacitances 15 and 16 in the vicinity of each side of the card-shaped casing 1, and the fluctuation amount is large. On the other hand, in the present invention, as described in Embodiment 1,
In the vicinity of B, the resonance frequency is hardly fluctuated even if the stray capacitances 15 and 16 are generated.
Even if B is brought, the fluctuation of the resonance frequency is small.

On the other hand, when the stray capacitances 15 and 16 are connected to points on the loop conductor 2a other than the vertices A and B, generally, if the distance from that point to the vertices A or B becomes longer, It has the property that it is weaker to the stray capacitances 15 and 16 and the fluctuation amount of the resonance frequency is larger. This is because the inductance value between the connection points where the stray capacitances 15 and 16 are connected in parallel changes according to the distance.
This is because the resonance frequency determined according to the relationship with F.4 also varies according to the distance. In the loop conductor 2 according to the second embodiment, in order to solve the above points, portions other than the vertices A and B are not provided near the four sides of the card-shaped casing 1 but are arranged at distant positions. Therefore, the stray capacitances 15 and 16 generated when any one of the four sides is provided become small because the distance between the loop conductor 2a and the four sides increases.
It has the function of suppressing fluctuations in the resonance frequency. Therefore, it is possible to obtain a card-shaped transmission / reception device that is resistant to the stray capacitances 15 and 16 and has little fluctuation in resonance frequency as a whole.

In particular, as the distance from the vertices A and B to the capacitor 12 increases, the distance from each side of the card-shaped casing 1 to the card-shaped conductor 2a increases, and thus the weakness to the stray capacitances 15 and 16 occurs as described above. However, the configuration is such that the generated stray capacitances 15 and 16 are reduced.

Also, by reducing the area facing the human body on the short side, the effect of stray capacitance is reduced, and the impedance seen from the long side apex, which is susceptible to stray capacitance, becomes zero at the designated resonance frequency. Since the capacitance values of the capacitors 12 and 14 and the inductance values of the respective sides are determined so as to be as described above, it is possible to prevent the reception sensitivity from being lowered due to the resonance frequency fluctuation near the human body.

Embodiment 3 FIG. Embodiment 2 is an embodiment in which fluctuations in resonance frequency can be suppressed more effectively by making the shape of the loop conductor a polygon as shown in FIG.

FIG. 7 is a top view of the card-shaped transmitting / receiving apparatus 1 according to the third embodiment. In FIG. 7, the same reference numerals as those in FIG. 1 or FIG. 6 denote the same or corresponding parts, and 2b denotes an octagonal loop configured so that each vertex is arranged near four sides of the rectangular card-shaped casing 1. Conductor. The basic configuration of the third embodiment is the same as that of the second embodiment, and the basic operation and operation are also the same. Therefore, the features of the third embodiment will be described below.

In the loop conductor 2b of the third embodiment,
The area surrounded by the loop conductor 1 is increased by increasing the number of vertices A, B, C, and D compared to the second embodiment and devising the shape. Therefore, at the time of reception, the loop conductor 2b
Can be increased, and the receiving sensitivity can be improved.

In the conductor between the vertices A and D and between the vertices B and C, the positions where the capacitors 11 and 13 are arranged are set at positions far from the four sides of the card-shaped casing 1, and the floating generated by the hand 9 is set. The capacities 15 and 16 are reduced. Therefore, as described in the above-described embodiment, it is possible to obtain a card-shaped transmission / reception device with a small variation in resonance frequency and high reception sensitivity as a whole, including a conductor portion other than the vertices A, B, C, and D. It is as expected.

Embodiment 4 FIG. In the fourth embodiment, the number of vertices is increased by making the shape of the loop conductor a polygon as shown in FIG. 8, the resistance to stray capacitances 15 and 16 is increased, and the fluctuation of the resonance frequency can be suppressed more effectively. This is a possible embodiment.

FIG. 8 is a top view of the card-shaped transmitting / receiving apparatus 1 according to the fourth embodiment. 8, the same reference numerals as those in FIG. 1 or FIG. 7 denote the same or corresponding parts, and 2c denotes a hexagonal loop in which each vertex is arranged near four sides of the rectangular card-shaped casing 1. Conductor. 11
a to 11c correspond to the capacitors 11 in FIG. 7 and are arranged at intermediate points between the vertexes DH, HE, and EA, respectively, and the capacitance is between the vertices. Is set so as to resonate at the specified resonance frequency fr with the inductance of Similarly, 13a to 13c
Is equivalent to the capacitor 13 in FIG.
These are capacitors arranged between G, GF, and FB. The basic configuration of the fourth embodiment is the same as that of the third embodiment, and the basic operation and operation are also the same. Therefore, the features of the fourth embodiment will be described below.

In the loop conductor 2b of the fourth embodiment,
The area surrounded by the loop conductor 1 is further increased by further increasing the number of vertices A to H and devising the shape as compared with the third embodiment. Therefore, the voltage induced in the loop conductor 2b during reception can be further increased,
The receiving sensitivity can be further improved.

In particular, since the number of vertices A to H is increased to 8, the portions that are strong against the stray capacitances 15 and 16 increase accordingly, and the resonance frequency fluctuation can be more effectively prevented.

Embodiment 5 FIG. Embodiment 5 is an embodiment having a square card-shaped casing and a circular loop conductor.

FIG. 9 is a top view of the card-shaped transmitting / receiving apparatus 1 according to the fifth embodiment. In FIG. 9, the same reference numerals as those in FIG. 7 denote the same or corresponding parts, 1a is a square card-shaped casing, 2d is such that vertices A to D are arranged near four sides of the card-shaped casing 1a. Is a circular loop conductor. In this embodiment, the vertices A to D are selected such that the loop conductor comes closest to any one of the four sides of the card-shaped casing 1a, and AB, B-
The capacitors 11 to 14 corresponding to the inductances between C, CD, and DA are set to resonate at the designated resonance frequency fr. This is the same as the other embodiments. Therefore, the basic configuration of the fifth embodiment is the same as that of the other embodiments, for example, the third embodiment, and the basic operation and operation are also the same. Hereinafter, features of the fifth embodiment will be described.

In the fifth embodiment, the vertices A to D are selected near the sides of the card-shaped casing 1a4 on the loop conductor 2d. The reason is that, as described in the third embodiment, there is a high possibility that large stray capacitances 15 and 16 are generated as compared with other portions. It is necessary to do it. Therefore, also in the fifth embodiment, it is possible to obtain an effect that the resonance frequency fluctuation is suppressed.

Although the square card-shaped casing and the perfect circular loop conductor are used in the fifth embodiment, a rectangular card-shaped casing or an elliptical loop-shaped casing may be used.

Embodiment 6 FIG. Embodiment 6 is an embodiment in which the shape of the loop conductor is configured to be square, and four vertices A to D are arranged near four sides of the card-shaped casing.

FIG. 10 is a top view of the card-shaped transmitting / receiving apparatus 1 according to the sixth embodiment. In FIG. 10, the same reference numerals as those in FIG. 9 denote the same or corresponding parts, and 2e denotes a square loop conductor configured so that each vertex is arranged near four sides of the square card-shaped casing 1a. . The basic configuration of the sixth embodiment is similar to that of the fifth embodiment.
The same is true for the basic operation and operation, and an effect that resonance frequency fluctuation is suppressed can be obtained. Therefore, the loop conductor 2e may be square instead of circular as in the fifth embodiment.

The loop conductor 2e need not be square, but may be rectangular or have a shape as shown in other embodiments.

Further, in the same manner as in the second embodiment, for the square card-shaped housing 1a, the loop conductor shape 2e is reduced to a square in which each apex is positioned at the center of each side of the square card-shaped housing 1a to reduce the facing area. The stray capacitance 15,
There is also an effect of being less susceptible to the influence of the sixteen.

Further, since the loop conductor 2e does not pass through the four corners of the card-shaped casing, floating occurs when the four corners of the card-shaped casing 1a are sandwiched between the upper and lower faces as shown in FIG. The capacitances 15 and 16 are reduced, which helps prevent resonance frequency fluctuation. In particular, it is effective in a usage form having many four corners. This effect can be applied to other embodiments in which the card-shaped conductors 2a to 2d do not pass through the four corners.

Embodiment 7 FIG. Embodiment 7 is an embodiment in which the loop conductor is configured as shown in FIG.

FIG. 11 is a top view of the card-shaped transmitting / receiving apparatus according to the sixth embodiment. In FIG. 11, the same reference numerals as those in FIG. 9 denote the same or corresponding parts, 1 denotes a rectangular card-shaped housing, and 2f denotes a rectangular card-shaped housing.
A loop conductor provided with inscribed perfect circular conductors on both short sides and a parallel conductor connecting the two perfect circular conductors. The basic configuration of the seventh embodiment is the same as that of the fifth embodiment except that mainly the loop conductor 2f is different. The basic operation and operation are also the same, and the resonance frequency fluctuation is suppressed. Can be obtained.

Embodiment 8 FIG. Embodiment 7 is an embodiment in which a loop conductor is provided on both sides of a substrate to secure a large capacitance and to increase the loop area.

FIG. 12 is a top view (showing the front side) of the card-shaped transmitting / receiving apparatus according to the eighth embodiment. 12, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and 100 denotes a substrate for realizing the loop conductor on both surfaces, and 2g denotes loop conductors provided on both surfaces of the substrate 100, respectively. Here, vertices A to D represent four vertices of the loop conductor 2g provided on the surface of the substrate 100, respectively, and vertices A ′ to D ′ represent four vertices of the loop conductor 2g provided on the back surface of the substrate 100, respectively. ing.

The loop conductor 2g has the same pattern on the front surface and the back surface, and generates a large capacitance like a capacitor because of the structure in which the substrate 100 as an insulator is sandwiched between the front surface and the back surface. In particular, in this card-shaped transmission / reception device, in order to strengthen the short side of the card-shaped housing, which is a part that is often touched, the loop conductor 2g on the short side is increased in area to generate a large capacity in such a portion. I am trying to do it.

The long side of the loop conductor 2g is realized by a meander line for expanding the loop area and adjusting the inductor, and a resonance capacitor is provided on each surface at the midpoint of the side. If you set a large capacity as described above,
In order to cause the loop conductor 2g to resonate at the designated resonance frequency, a large inductance value corresponding to the capacitance is required. In this embodiment, the inductance value is increased by providing a meander line on the long side of the loop conductor 2g.

FIG. 13 is a circuit diagram showing an electric equivalent circuit of the card-shaped transmitting / receiving apparatus shown in FIG. 12, and the same reference numerals as those in FIG. 2 represent the same or corresponding parts. Reference numeral 120 denotes a resistance and a capacitance in a wide area portion provided between the vertices AB and A′-B ′ of the loop conductor 2g;
Similarly, 0 is a wide area portion provided between vertices C and D and C ′ and D ′ (hereinafter, a wide area portion including vertices A and B and a wide area portion provided between A ′ and B ′). (Referred to as an area conductor). Reference numeral 17 denotes a stray capacitance generated when a person holds the vicinity of the short side of the card-shaped casing 1.

On the short side of each surface of the substrate 100, a capacitor capable of realizing a capacitor with negligible stray capacitance 17 when sandwiched by a finger is formed of a wide-area conductor over the entire short side, and the stray capacitance 17 This makes it possible to reduce the effect of

The capacitors 12 and 14 are provided for adjusting the resonance frequency, and are connected in parallel to the capacitors formed of a wide area conductor on both short sides. Capacitor 1
Reference numerals 1 and 13 are set so that the impedance between the large-area conductors on the same surface on the short side becomes zero, and the whole circuit resonates.

Next, the operation will be described. When the card-shaped housing 1 is held by hand, between A and B, between C and D, and A'-
A stray capacitance 17 is generated between B 'and C'-D'. The stray capacitance 17 causes a variation in resonance frequency. However, in the loop conductor 2g, the stray capacitance 17 is generated because the large-area conductor provided on the short side of the loop conductor 2g has a large capacitance. Even in this case, the fluctuation of the entire capacitance is small, and the fluctuation of the resonance frequency can be suppressed to a small value. That is, the stray capacitance 17 occupying the entire capacitance of the loop conductor 2g
Is set to a negligible level, so that the resonance frequency fluctuation can be suppressed to a small level. In general, when the facing area is S, the facing dimension is t, the relative permittivity is μ _S , and the air permittivity is μ ₀ , the capacitance C is C = μ _S μ ₀ S
/ T.

Further, the card-shaped casing 1 is not affected much by the way of holding it. For example, even when the card-shaped casing 1 is held so that the front and back surfaces on the short side are sandwiched between fingers, resonance occurs. Frequency fluctuation can be suppressed.

Further, unlike the related art 2, there is no problem that the area surrounded by the loop conductor is reduced, and a large induced voltage E ₀ is obtained.

In the above description, a capacitor capable of absorbing stray capacitance with a wide-area conductor is formed on the short side to prevent the influence of the human body. However, instead of the wide-area conductor on the short side, the capacitor has a designated resonance frequency. A thin high dielectric resonator may be provided, and the stray capacitance due to the proximity of the human body is absorbed by the high dielectric resonator on the single side, and the same effect is obtained.

Similarly, a similar effect can be obtained by disposing a large number of capacitors on the short side instead of the wide area conductor on the short side to absorb the stray capacitance due to the proximity of the human body.

In addition, since the capacitors can be easily formed by arranging the loop conductors on both sides of the substrate, the number of capacitors can be reduced and the wireless card can be made thinner.

Further, in this embodiment, the rectangular casing 1
Although the wide area conductor is provided on the short side of the above, even if it is provided on the long side, the effect that the resonance frequency fluctuation due to the stray capacitance can be suppressed can be obtained.

Further, in this embodiment, the loop conductors 2g are provided on both sides of the substrate 100, but the same effect can be obtained by disposing the loop conductors in the intermediate layer of the multilayer substrate.

[0108]

Since the present invention is configured as described above, it has the following effects.

A thin housing containing a receiver, a loop antenna inside the housing for receiving radio waves and connected to the receiver, and floating between two predetermined points on the loop antenna. Between the capacitance connection points and inserted in series with the loop antenna between the stray capacitance connection points, and the loop antenna
And a capacitive reactance element having a capacitance set so as to resonate at the reception frequency of the loop antenna , the capacitive reactance and the floating at the reception frequency of the loop antenna between predetermined floating capacitance connection points. Since the inductive reactance between the capacitive connection points resonates, a maximum current flows, and the effect of the stray capacitance connected in parallel with the capacitive reactance and the inductive reactance can be suppressed. That is,
Variations in the resonance frequency due to stray capacitance generated when something comes into contact with or approaches the housing can be suppressed, and a decrease in reception sensitivity can be prevented.

A thin housing containing a receiver, a portion inside the housing for receiving radio waves and connected to the receiver and having a long distance to an outer frame of the housing; The loop antenna having a plurality of portions where the distance is relatively short, and the plurality of short portions each serving as a stray capacitance connection point. The stray capacitance connection point is inserted in series with the loop antenna between these stray capacitance connection points. because of and a capacitive reactance elements set the capacity to resonate at the receiving frequency of the loop antenna between, in between the floating capacitance connected points predetermined the
The maximum current flows because the inductive reactance between the capacitive reactance and the stray capacitance connection point resonates at the receiving frequency of the loop antenna, and the effect of the stray capacitance connected in parallel with the capacitive reactance and the inductive reactance is suppressed. be able to. In particular, in a portion where the distance to the outer frame of the housing is short, a large stray capacitance is generated, so that the influence of such a large stray capacitance is suppressed, and in other portions, the distance to the outer frame of the housing is increased. And the generated stray capacitance is kept small. Accordingly, even when the above-mentioned long portion other than the stray capacitance connection point is provided, there is an effect of suppressing the resonance frequency fluctuation.
That is, it is possible to more effectively suppress the fluctuation of the resonance frequency caused by the stray capacitance generated when another object touches or approaches the housing, and it is possible to prevent the reception sensitivity from lowering.

The capacitive reactance element is inserted in series with the loop antenna between the stray capacitance connection points, and the insertion position is a middle point between the stray capacitance connection points. Because it is at the midpoint, the inductive reactance on the loop antenna on one side of the capacitive reactance element and the inductive reactance on the other side can be balanced, and the fluctuation of the resonance frequency can be suppressed more effectively. In addition, it is possible to prevent a decrease in reception sensitivity.

The loop antenna is constituted by a polygon having a vertex arranged near the outer frame of the housing and a vertex arranged far away, and the capacitive reactance element is arranged far from the housing. The loop antenna is inserted between the vertices that are
Because the capacitance is set to resonate at the receiving frequency of the
Variations in the resonance frequency caused by stray capacitance generated when another object touches or approaches the housing can be more effectively suppressed, and a decrease in reception sensitivity can be prevented.

Since the housing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape, the resonance frequency generated by stray capacitance generated when another object touches or approaches the housing. Fluctuations can be suppressed more effectively, and a decrease in reception sensitivity can be prevented.

A thin housing containing a receiver, a board built in the housing, and a first loop antenna disposed on one surface of the board and connected to the transmitter for receiving radio waves. A second loop antenna disposed on the other surface of the substrate and connected to the transmitter to receive a radio wave; a first plate-shaped conductor provided on the first loop antenna; And a second plate-shaped conductor provided to face the first plate-shaped conductor so as to generate capacitance between the loop antenna and the first plate-shaped conductor. The first loop antenna or the second
Constitutes a loop antenna, increases the area surrounded by the loop antenna, obtains a large induced voltage, and generates a large capacitance between the first plate-shaped conductor and the second plate-shaped conductor. The effect of stray capacitance can be suppressed by using components or low-volume components, and an effect suitable for a thin receiving device can be obtained in that the device can be reduced in size and thickness as a whole.

A thin housing containing a transmitter, a loop antenna in the housing for transmitting radio waves and connected to the transmitter, and floating between two predetermined points on the loop antenna. Between the capacitance connection points and inserted in series with the loop antenna between the stray capacitance connection points, and the loop antenna
And a capacitive reactance element having a capacitance set so as to resonate at a transmission frequency of between the stray capacitance connection point and a floating reactance element at a reception frequency of the loop antenna between predetermined floating capacitance connection points. Since the inductive reactance between the capacitive connection points resonates, a maximum current flows, and the effect of the stray capacitance connected in parallel with the capacitive reactance and the inductive reactance can be suppressed. That is,
Suppressing variation in the resonant frequency due to the stray capacitance that occurs when others in housing or close when touched, it is possible to prevent the transmit sensitivity lowered.

A thin housing containing a transmitter, a portion inside the housing for transmitting radio waves and connected to the transmitter and having a long distance to an outer frame of the housing, The loop antenna having a plurality of portions where the distance is relatively short, and the plurality of short portions each serving as a stray capacitance connection point. The stray capacitance connection point is inserted in series with the loop antenna between these stray capacitance connection points. A capacitive reactance element whose capacitance is set so as to resonate at the transmission frequency of the loop antenna between the stray capacitance connection points between the predetermined stray capacitance connection points and the designated resonance frequency. The largest current flows due to the resonance of the inductive reactance between the inductive reactance and the floating connected in parallel with the capacitive reactance and the inductive reactance. It is possible to suppress the influence of the amount.
In particular, in a portion where the distance to the outer frame of the housing is short, a large stray capacitance is generated, so that the influence of such a large stray capacitance is suppressed, and in other portions, the distance to the outer frame of the housing is increased. And the generated stray capacitance is kept small. Accordingly, even when the above-mentioned long portion other than the stray capacitance connection point is provided, there is an effect of suppressing the resonance frequency fluctuation. In other words, suppressing the variation of the resonance frequency generated by the stray capacitance generated when or approached when the others to the housing touches more effectively, it is possible to prevent the transmit sensitivity lowered.

The capacitive reactance element is inserted in series with the loop antenna between the stray capacitance connection points, and the insertion position is a middle point between the stray capacitance connection points. one can balance the inductive reactance in the inductive reactance and the other side on the side of the loop-loop antenna, suppress the variation of the resonance frequency more effective, it is possible to prevent the transmit desensitization it can.

The loop antenna is constituted by a polygon having a vertex arranged near the outer frame of the housing and a vertex arranged far away, and the capacitive reactance element is arranged far from the housing. The loop antenna is inserted between the vertices that are
Because the capacitance is set to resonate at the transmission frequency of the
Suppressing variation in the resonance frequency caused by the stray capacitance that occurs when the others to the housing is approaching or when touched more effectively, it is possible to prevent the transmit sensitivity lowered.

Since the housing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape, the resonance frequency generated by the stray capacitance generated when another object touches or approaches the housing. suppressing variation more effectively, it is possible to prevent the transmit sensitivity lowered.

A thin housing containing a transmitter, a substrate built in the housing, and a first loop antenna disposed on one surface of the substrate and connected to the transmitter for transmitting radio waves. A second loop antenna disposed on the other surface of the substrate and connected to the transmitter to transmit a radio wave; a first plate-shaped conductor provided on the first loop antenna; 2 is provided on the second loop antenna, and is provided to face the first plate-shaped conductor so as to generate a capacitance between the loop antenna and the first plate-shaped conductor.
The loop antenna or the second loop antenna constitutes a loop antenna, increases the area surrounded by the loop antenna, transmits a strong radio wave, and increases the size of the first and second plate conductors. It is possible to obtain an effect suitable for a thin transmitting device in which the capacity can be generated and the influence of the stray capacity can be suppressed with a small number of components or low volume components.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 1 of the present invention.

FIG. 2 is an electrical equivalent circuit of the card-shaped transmitting / receiving device according to Embodiment 1 of the present invention.

FIG. 3 is an electrical equivalent circuit of the card-shaped transmitting / receiving apparatus according to Embodiment 1 of the present invention.

FIG. 4 is an external view of the card-shaped transmitting / receiving apparatus according to Embodiment 1 of the present invention when the card-shaped transmitting / receiving apparatus is held by hand.

FIG. 5 is a simplified electrical equivalent circuit of the card-shaped transmitting / receiving apparatus according to Embodiment 1 of the present invention.

FIG. 6 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 3 of the present invention.

FIG. 8 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 4 of the present invention.

FIG. 9 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 5 of the present invention.

FIG. 10 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 6 of the present invention.

FIG. 11 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 7 of the present invention.

FIG. 12 is a configuration diagram of a card-shaped transmitting / receiving apparatus according to Embodiment 8 of the present invention.

FIG. 13 is an electrical equivalent circuit of a card-shaped transmitting / receiving apparatus according to Embodiment 8 of the present invention.

FIG. 14 is a configuration diagram of a transmission / reception apparatus according to the conventional technique 1.

FIG. 15 is a development view in which the transmission / reception device of the related art 1 is developed in a plane.

FIG. 16 is an electrical equivalent circuit of the transmission / reception device of the related art 1.

FIG. 17 is a configuration diagram of a transmission / reception device according to the related art 2.

FIG. 18 is a cross-sectional view of a transmission / reception device according to the related art 2.

FIG. 19 is an electrical equivalent circuit of a transmission / reception device according to the related art 2.

FIG. 20 is a configuration diagram of a transmission / reception apparatus according to the conventional technique 3.

FIG. 21 is an electrical equivalent circuit of a transmission / reception device according to Conventional Technique 3.

[Explanation of symbols]

1, 1a · b housing, 2, 2a to 2g loop conductor,
3 transmission / reception circuit, 9 hands, 11-14 capacitors,
15-17 stray capacitance, 31, 32 connection line, 2
10-241 Equivalent electric element of loss resistance and inductance generated on each side, 100 substrate.

Claims (12)

(57) [Claims] 1. A thin housing in which a receiver is built, a loop antenna in the housing for receiving radio waves and connected to the receiver, and between a predetermined two points on the loop antenna. Between the stray capacitance connection points, and a capacitive reactance element which is inserted in series with the loop antenna between the stray capacitance connection points and whose capacitance is set so as to resonate at the reception frequency of the loop antenna between the stray capacitance connection points. And a thin receiving device comprising: 2. A thin housing containing a receiver, a portion inside the housing for receiving radio waves and connected to the receiver and having a long distance to an outer frame of the housing;
A loop antenna having a plurality of portions where the distance is shorter than the long portion, and each of the plurality of short portions is a stray capacitance connection point, which is inserted in series with the loop antenna between these stray capacitance connection points. The above loop between the stray capacitance connection points
And a capacitive reactance element having a capacitance set so as to resonate at a reception frequency of the loop antenna . 3. The method according to claim 2, wherein the capacitive reactance element is inserted in series with the loop antenna between the floating capacitance connection points, and the insertion position is a middle point between the floating capacitance connection points. The thin receiving device according to claim 1. 4. The loop antenna is constituted by a polygon having a vertex arranged near an outer frame of the housing and a vertex arranged far away, and the capacitive reactance element is
The loop antenna is inserted between vertices arranged far away from the housing, and between the vertices arranged near the housing.
3. The thin receiver according to claim 1, wherein the capacitance is set so as to resonate at a reception frequency of the tenor . 5. The thin receiving device according to claim 1, wherein the housing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape. And thin housing having a built-in 6. A receiver, and a substrate incorporated in the housing, a first receiving radio waves are connected to the receiver while being arranged on one surface of the substrate and the loop antenna, and a second loop antenna for receiving radio waves are connected to the receiver while being disposed on the other surface of the substrate, a first plate-shaped conductor provided on the first loop antenna, A second plate-shaped conductor provided on the second loop antenna and opposed to the first plate-shaped conductor so as to generate a capacitance between the second loop antenna and the first plate-shaped conductor. A thin receiving device. 7. A thin housing in which a transmitter is built, a loop antenna in the housing for transmitting radio waves and connected to the transmitter, and a predetermined point on the loop antenna between two predetermined points. Between the stray capacitance connection points, is inserted in series with the loop antenna between the stray capacitance connection points, and has a capacitance set between the stray capacitance connection points so as to resonate at the transmission frequency of the loop antenna. And a thin transmitting device comprising: 8. A thin housing containing a transmitter, a portion inside the housing that transmits radio waves and is connected to the transmitter and has a long distance to an outer frame of the housing.
A loop antenna having a plurality of portions where the distance is shorter than the long portion, and each of the plurality of short portions is a stray capacitance connection point, which is inserted in series with the loop antenna between these stray capacitance connection points. The above loop between the stray capacitance connection points
And a capacitive reactance element whose capacitance is set so as to resonate at the transmission frequency of the loop antenna . 9. The method according to claim 8, wherein the capacitive reactance element is inserted in series with the loop antenna between the floating capacitance connection points, and the insertion position is a middle point between the floating capacitance connection points. A thin transmitting device according to claim 7. 10. The loop antenna is constituted by a polygon having a vertex arranged near an outer frame of the housing and a vertex arranged far away, and the capacitive reactance element is arranged at a distance from the housing. 8. A capacitor which is inserted into a vertex portion disposed at a position between the loop antenna and a resonance frequency at a transmission frequency of the loop antenna between vertices disposed near the housing.
Or the thin transmitting device according to 8. 11. The thin transmitting device according to claim 7, wherein the casing is formed in a rectangular or square shape, and the loop antenna is formed in a circular shape. 12. A thin housing containing a transmitter, a board contained in the housing, and a first board disposed on one surface of the board and connected to the transmitter for transmitting radio waves. A loop antenna, a second loop antenna disposed on the other surface of the substrate and connected to the transmitter for transmitting radio waves, a first plate-shaped conductor provided on the first loop antenna, A second plate-shaped conductor provided on the second loop antenna and opposed to the first plate-shaped conductor so as to generate a capacitance between the second loop antenna and the first plate-shaped conductor. Thin transmitting device.