KR101467677B1 - Nfc antenna and apparatus comprising nfc antenna - Google Patents

Abstract

The present invention relates to an antenna for a short range communication and a short range communication device including the same. An antenna for short-range communication includes a base substrate; A first conductive pattern arranged on one surface of the base substrate in a loop pattern and having both ends of the loop pattern connected to the antenna feeding portion; And a second conductive pattern formed on one surface of the base substrate and spaced apart from the first conductive pattern by a first conductive pattern and formed in a loop pattern. The base substrate, the short-range communication antenna including the first conductive pattern P1 and the second conductive pattern P2 can be used as a battery of a mobile communication terminal such as a feature phone or a smart phone, a rear case of a mobile communication terminal, Card, and a transportation card terminal, a RFID transceiver, a storage medium such as a USIM-chip, a USB embedded in a mobile communication terminal, or an electronic device.

Description

TECHNICAL FIELD [0001] The present invention relates to an antenna for short-range communication and a short-

The present invention relates to an antenna for a short range communication and a short range communication device including the same.

Near Field Communication (NFC) is a term used to refer to the 13.56 MHz band non-contact type short-range wireless communication technology. It is capable of providing data communication between mobile devices, especially smart phones, as well as existing contactless smart card technology and wireless And provides interoperability with RFID.

 Since the establishment of the International Standard for NFC communication standards (ISO / IEC 18092) in 2003 and the establishment of the NFC Forum in 2004, the term NFC began to be officially used. Prior to that, most of the 13.56 MHz wireless communication technologies were used for contactless smart card technology Category.

Currently, the existing contactless smart card technology has been widely used for subway, bus, and credit cards, and is also used in the field of distribution and logistics in the form of RFID tags.

However, efforts to install contactless wireless communication technology in personal mobile phones have been continuing with the adoption of dedicated reader and IC card type fixed services. In particular, Nokia, one of the world's leading manufacturers of mobile phones, We have released it.

However, due to limited wireless Internet access, there is a lack of service interconnection, a limited use of general mobile phones, and an absolutely lack of NFC-equipped mobile devices.

 However, with the recent proliferation of smartphones, new trends are being recognized in the field of NFC. At present, iOS and Android, which are typical operating systems for smartphones, provide a convenient wireless Internet access environment. Therefore, attempts to utilize NFC technology as a mobile credit card, RFID reader / tag, and data transmission device as a smart phone are becoming a realistic service model .

In particular, major credit card companies such as Visa and MasterCard are actively supporting the adoption of NFC technology, and NFC support for smartphone operating systems such as Google's Android OS and Nokia's Symbian OS is also increasing.

 The NFC antenna communicates through inductive coupling in the near field. In the ISO / IEC 18092 standard, the NFC reader antenna is 1.5 A / m <| H | &Lt; 7.5 A / m. One of the most important concerns for reader antennas is to increase the recognition distance while satisfying this condition.

In addition, the NFC antenna is matched to 13.56 MHz through a matching circuit. However, because of the inductive coupling method, if other NFC antennas are close to each other in a short distance, a mutual inductance is formed in the inductance of the original antenna, so that the inductance of the antenna is changed and the resonance frequency is separated into two, ) Problem occurs.

Therefore, an inductive coupling transponder must be precisely matched to the resonant frequency of the reader antenna for smooth power supply and optimization of the reading sensitivity. However, transponders in actual use are generally tuned up in frequency and are manufactured at several frequencies depending on the application. In order to solve this problem, studies have been made to reduce the phenomenon that the resonance frequency is detuned through the automatic matching circuit.

However, such an automatic matching circuit has a problem of increasing the manufacturing cost of a short-range communication device including an NFC antenna and increasing the complexity of the device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna for a short-range communication which can minimize the detuning phenomenon and a short-range communication device including the same.

The antenna for short-range communication according to the present invention is a dielectric substrate including ferrite as a magnetic material for shielding or reflecting electromagnetic waves and having a permittivity (epsilon r) of 3.0 to 5.0, and the glass fiber impregnated with the epoxy resin is composed of multiple layers Base board using stacked FR-4 board; A first conductive pattern disposed on one surface of the base substrate in a loop pattern and having both ends of the loop pattern connected to the antenna feeding portion; And a second conductive pattern formed on one surface of the base substrate and spaced apart from the first conductive pattern by a first conductive pattern and formed in a loop pattern,
An impedance matching portion is provided at an end of the first conductive pattern adjacent to the antenna feeding portion for impedance matching between the first conductive pattern P1 and the antenna circuit. The impedance matching portion includes a plurality of capacitor elements Wherein the first conductive pattern is formed in a pattern having a plurality of loops in order to reduce an area of the antenna while securing a resistance value, a capacitance value, and an inductance value of the antenna, the loop pattern included in the first conductive pattern,
Wherein a direction of a current flowing through the second conductive pattern is opposite to a direction of a current flowing through the first conductive pattern and a current flowing through the second conductive pattern is induced by a current flowing in the first conductive pattern, The magnetic field H generated in the second conductive pattern and the magnetic field H generated in the first conductive pattern are canceled due to the phases of the different electric currents so that the size H of the magnetic field in the adjacent area can be reduced, And the frequency detuning phenomenon that the operating frequency of the antenna for short-range communication is separated and moved when the antennas for short-range communication are close to each other is suppressed.

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The number of revolutions of the loop pattern included in the first conductive pattern is plural, the plurality of loop patterns included in the first conductive pattern are connected to each other, and the number of revolutions of the loop pattern included in the second conductive pattern is plural , The plurality of loop patterns included in the second conductive pattern may be spaced apart from each other.

Here, the number of revolutions of the second conductive pattern may be between two and six.

The spacing between the first conductive pattern and the second conductive pattern may be wider than the spacing between the respective loop patterns in the first conductive pattern or between the respective loop patterns in the second conductive pattern.

Here, the width of each loop pattern in the first conductive pattern may be the same as the interval between the respective loop patterns in the first conductive pattern, and the width of each loop pattern in the second conductive pattern may be May be the same as the interval between the loop patterns of FIG.

In addition, the width of each loop pattern in the first conductive pattern may be the same as the width of each loop pattern in the second conductive pattern.

Also, the local area communication apparatus according to the present invention may include the above-described local area communication antenna.

Also, the mobile communication terminal according to the present invention may include the above-described short-range communication antenna.

The antenna for a short-range communication according to the present invention and the short-range communication device including the antenna for short-range communication do not need to have a separate automatic matching circuit for preventing a detuning phenomenon by forming a conductive pattern on the antenna that can minimize a detuning phenomenon, It is possible to minimize the manufacturing cost of the short-range communication antenna and the short-range communication device including the same.

1 is a view for explaining an example of an antenna for a short distance communication according to the present invention.
2 is a view for explaining an example of the operation of the antenna for short-range communication shown in Fig.
FIGS. 3 and 4 are diagrams for explaining the comparison between the magnitude of the magnetic field of the short-range communication antenna according to the present invention and the magnitude of the magnetic field of the short-range communication antenna without the second conductive pattern.
4 is a diagram for explaining a magnetic field size of a short-range communication antenna according to a vertical distance from a center point of a short-range communication antenna to a front direction.
5 is a view for explaining a magnetic field change according to the number of turns (turn number) of a plurality of loop patterns included in the second conductive pattern in the antenna for short-range communication according to the present invention.
FIGS. 6 to 8 are diagrams for explaining the difference in the frequency detuning phenomenon according to the present invention and the comparative example.
9 is a diagram for explaining a difference in power transmission rate according to the present invention and a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

1 is a view for explaining an example of an antenna for a short distance communication according to the present invention.

1, an antenna 100 for short-range communication according to the present invention may include a base substrate 10, a first conductive pattern P1, and a second conductive pattern P2.

Here, the base substrate 10 may be a dielectric substrate having a dielectric constant epsilon r of 3.0 to 5.0. For example, the base substrate 10 may be made of FR- 4 substrate, and the dielectric constant of the base substrate 10 may be 4.4.

In addition, the thickness of the base substrate 10 may be between 0.4 mm and 1.2 mm, for example, the thickness of the base substrate 10 may be 0.8 mm.

However, the material, permittivity, and thickness of the base substrate 10 are not necessarily limited to those described above, and may be changed.

In addition, a magnetic material such as ferrite may be included in the base substrate 10 to shield or reflect electromagnetic waves.

The first conductive pattern P1 may be arranged in a loop pattern in the outer area S1 of one side of the base substrate 10 so that the first conductive pattern P1 can perform a function of transmitting or receiving a signal for short- , Both ends of the loop pattern included in the first conductive pattern P1 may be connected to the antenna feeding part 30. [

Accordingly, the signal received by the first conductive pattern P1 can be transmitted to the antenna circuit for processing the signal received through the antenna feeding part 30. In addition, when transmitting the signal, the signal to be transmitted is It can be transmitted through the antenna feeding part 30 and the first conductive pattern P1.

At this time, in order to achieve impedance matching between the first conductive pattern P1 and the antenna circuit, the impedance matching unit 20 is provided at the end of the first conductive pattern P1 adjacent to the antenna feeder 30 .

The impedance matching unit 20 may include a plurality of capacitor elements. Specifically, the plurality of capacitor elements may include a first capacitor 20a connected in series to the first conductive pattern P1, 2 capacitor 20b and a third capacitor 20c connected to both ends of the first conductive pattern P1.

As shown in FIG. 1, the first conductive pattern P1 includes a loop pattern (not shown) included in the first conductive pattern P1 to reduce the area of the antenna while securing a resistance value, a capacitance value, and an inductance value of an appropriate antenna. May be formed in a pattern having a plurality of loops.

Accordingly, the operating frequency of the short-range communication antenna 100 formed by the first conductive pattern P1 and the impedance matching unit 20 can realize 13.56 MHz according to the non-contact type standard wireless communication technology.

As described above, the plurality of loop patterns included in the first conductive pattern P1 are formed in one line, and one current path formed by the plurality of loop patterns can be one.

Therefore, the number of turns of the plurality of loop patterns included in the first conductive pattern P1 may be between two and six times. For example, the resistance value of the first conductive pattern P1, the capacitance value And the inductance value, it may be four times as shown in FIG. 1, but it is not necessarily limited thereto.

The second conductive pattern P2 is formed on the inner region S2 of the first conductive pattern P1 surrounded by the first conductive pattern P1 on one side of the base substrate 10, As shown in FIG.

The second conductive pattern P2 may be formed in a closed loop pattern differently from the first conductive pattern P1. Here, the number of turns of the loop pattern included in the second conductive pattern P2 may be between 2 and 6, and may be, for example, 4, but is not limited thereto and may be changed.

The second conductive pattern P2 will be described below in comparison with the first conductive pattern P1.

For example, as shown in FIG. 1, there may be one current path formed by a plurality of loop patterns included in the first conductive pattern P1, and the current path may be one antenna feeding part 30 = (P1) ==> the antenna feeding part 30 can be formed.

However, the second conductive pattern P2 may not be electrically connected to the antenna feeding part 30 or the first conductive pattern P1 but may be formed to be spaced apart from the first conductive pattern P1, The plurality of loop patterns included in the conductive pattern P2 may be closed loop patterns each having a current path independent of each other.

The second conductive pattern P2 is used for the operation of the short range communication antenna 100 when the two short range communication antennas 100 approach each other when the short distance communication antenna 100 performs a function of transmitting or receiving signals. It is possible to perform a function of suppressing a frequency detuning phenomenon in which frequencies are separated and moved.

This frequency detuning phenomenon occurs when the magnitude of the magnetic field generated when the antenna 100 for short-distance communication is operated is excessively large, and when the magnitude of the magnetic field is adequately small, detuning of the frequency detuning is suppressed can do.

This frequency detuning phenomenon generates an error bit when transmitting / receiving the short distance communication antenna 100 to lower the recognition rate or the power transmission rate of the short distance communication antenna 100, Can be prevented from operating normally.

In this regard, the concrete structure of the first conductive pattern P1 and the second conductive pattern P2 will be described first, and will be described in more detail later with reference to FIG.

The loop shape of the first conductive pattern P1 and the second conductive pattern P2 may have a tetragonal shape as shown in FIG. 1, but may be formed in various shapes such as a polygonal shape, a circular shape, or an elliptical shape.

That is, the loop shape of the first conductive pattern P1 has a plurality of revolutions and one current path as a whole, and both ends thereof may be connected to the antenna feeding part 30. [

Therefore, the plurality of loops contained in the first conductive pattern P1 may be connected to each other.

 The closed loop shape of the second conductive pattern P2 may be in the form of a closed loop that is not electrically connected to the first conductive pattern P1 or the antenna feeding portion 30, The plurality of current paths formed by the closed-loop type of the switching elements may be independent of each other.

Therefore, each of the plurality of closed loop shapes of the second conductive pattern P2 can be formed without being connected to each other.

1, the spacing DP between the first conductive pattern P1 and the second conductive pattern P2 is equal to the distance DP1 between the respective loop patterns in the first conductive pattern P1 ) Or the interval DP2 between the respective loop patterns in the second conductive pattern P2.

The spacing DP between the first conductive pattern P1 and the second conductive pattern P2 is relatively widened by forming a separate space between the first conductive pattern P1 and the second conductive pattern P2. Thereby preventing a capacitance component from being generated.

For example, when the spacing distance DP between the first conductive pattern P1 and the second conductive pattern P2 is excessively close, a capacitance is formed between the first conductive pattern P1 and the second conductive pattern P2, And the capacitance value of the first conductive pattern P1 may be influenced.

In such a case, the resonance frequency Wo of the first conductive pattern P1 determined according to the resistance value, the capacitance value, and the inductance value may be influenced, and the signal transmission / reception ratio may be lowered. Therefore, in order to prevent this, the spacing DP between the first conductive pattern P1 and the second conductive pattern P2 can be relatively widened.

More specifically, the spacing DP between the first conductive pattern P1 and the second conductive pattern P2 is set to a distance DP1 between the respective loop patterns in the first conductive pattern P1, P2) between 4 and 12 times the interval DP2 between the respective loop patterns.

For example, the spacing DP between the first conductive pattern P1 and the second conductive pattern P2 may be between 2 mm and 6 mm, preferably 4 mm. However, the spacing distance DP between the first conductive pattern P1 and the second conductive pattern P2 is not necessarily limited thereto.

Here, the width WP1 of each loop pattern in the first conductive pattern P1 may be equal to the interval DP1 between the respective loop patterns in the first conductive pattern P1. For example, when the width WP1 of each loop pattern in the first conductive pattern P1 is 0.5 mm, the interval DP1 between the respective loop patterns in the first conductive pattern P1 may be 0.5 mm have.

However, the present invention is not limited to this, and the capacitance value of the first conductive pattern P1 may vary according to the width WP1 of each loop pattern in the first conductive pattern P1, And the inductance value according to the total length of the plurality of loop patterns included in the loop pattern.

The width WP2 of each loop pattern in the second conductive pattern P2 may be equal to the interval DP2 between the respective loop patterns in the second conductive pattern P2. For example, the width WP2 and the spacing DP2 of each loop pattern in the second conductive pattern P2 may be 0.5 mm.

Therefore, the width WP1 of each loop pattern in the first conductive pattern P1 may be the same as the width WP2 of each loop pattern in the second conductive pattern P2.

In addition, the base station 10, the short-range communication antenna 100 including the first conductive pattern P1 and the second conductive pattern P2 can be used as a battery of a mobile communication terminal such as a feature phone or a smart phone, At least one of a short distance communication device such as a back case of a communication terminal, a transportation card of a bus or a subway, a short distance communication device such as a transportation card terminal, an RFID transceiver, a storage medium such as a USIM- As shown in FIG.

In addition, the antenna 100 for short-range communication according to the present invention can be used in three modes (specifically, Read / Write, Card emulation, Peer to Peer mode) in which the system including the antenna for short- It is possible to perform near field wireless communication through the antenna 100 for communication.

2 is a view for explaining an example of the operation of the antenna for short-range communication shown in Fig.

2, a current applied to the first conductive pattern P1 may be generated by transmission or reception of a signal in the antenna 100 for short-range communication according to the present invention. At this time, The direction of the current IP2 flowing through the second conductive pattern P2 may be opposite to the direction of the current IP1 flowing through the first conductive pattern P1 as shown in FIG. The flowing current may be a current induced by the current IP1 flowing in the first conductive pattern P1.

More specifically, a magnetic field (H) can be generated around the first conductive pattern P1 by the current IP1 flowing in the first conductive pattern P1 on the outer side, and the first conductive pattern P1 The current IP2 can flow through the second conductive pattern P2 located inside the first conductive pattern P1 by the magnetic field around the first conductive pattern P1. The current flowing through the second conductive pattern P2 at this time is determined by the reaction against the magnetic field H generated by the current IP1 flowing through the first conductive pattern P1 and by the Faraday's law, A current having a phase opposite to the phase of the current IP1 flowing through the transistor P1 can be generated.

Therefore, the magnetic field generated in the second conductive pattern P2 and the magnetic field H generated in the first conductive pattern P1 are canceled by the phases of different currents, thereby reducing the size H of the magnetic field in the adjacent region Therefore, it is possible to suppress a frequency detuning phenomenon in which the operating frequency of the antenna for short-range communication 100 is separated and moved when the two short-range communication antennas 100 are close to each other.

Here, in the antenna 100 for short-range communication according to the present invention, the decrease in the size of the magnetic field of the antenna 100 for short-range communication due to the second conductive pattern P2 can be confirmed in FIG.

FIGS. 3 and 4 are diagrams for explaining the comparison between the magnitude of the magnetic field of the short-range communication antenna according to the present invention and the magnitude of the magnetic field of the short-range communication antenna without the second conductive pattern.

3 (a) is a photograph of the cross-sectional size H of the magnetic field generated by the antenna 100 for short-distance communication according to the present invention. FIG. 3 (b) Sectional size H of the magnetic field generated by the short-range communication antenna 200 in which the second conductive pattern P2 is omitted from the communication antenna.

As shown in Fig. 3A, the cross-sectional size H of the magnetic field generated by the antenna 100 for short-range communication according to the present invention is smaller than that of the first conductive pattern P1, and the area where the second conductive pattern P2 is located sharply decreases so that a strong magnetic field is generated in a circular shape only in the outer portion of the antenna 100 for short- It can be seen that the magnetic field is very weakly formed in the inner region of the substrate 100.

However, as shown in Fig. 3 (b), in the comparative example, there is no second conductive pattern P2, and it is confirmed that a relatively strong magnetic field is formed not only in the outer portion of the antenna 100 for short- .

4 is a view for explaining the magnetic field size of the short-range communication antenna according to the vertical distance from the center point of the short-range communication antenna to the front direction.

4A is a value obtained by measuring the magnetic field size H of the antenna 100 for short-distance communication according to the present invention with distance. FIG. 4B is a comparative example, (H) of the magnetic field generated by the antenna for short-range communication 200 in which the second conductive pattern P2 is omitted in FIG.

4, the antenna 100 for short-range communication according to the present invention is formed by the second conductive pattern P2 so that the distance from the center point of the antenna 100 for short-range communication, as defined by the ISO / IEC 18092 standard When the size (H) of the magnetic field of the antenna 100 for short range communication is 1.5 A / m < | H | &Lt; 7.5 A / m.

However, in the comparative example, the distance from the center point of the short distance communication antenna 200 to the distance of approximately 20 mm to 50 mm is not satisfied by the second conductive pattern P2, but the distance is approximately If it is less than 20mm, it can be confirmed that it does not satisfy ISO / IEC 18092 standard.

Therefore, in the comparative example, when the two short-range communication antennas 200 are very close to each other, as described above, the frequency detuning phenomenon is likely to occur in the comparative example. In such a case, An error bit is generated at the time of transmitting / receiving the short range communication antenna 200, and therefore the recognition rate or the transmission rate of the short range communication antenna 200 is significantly lowered, so that the short range communication antenna 200 may not operate normally.

However, the antenna 100 for short-range communication according to the present invention is designed such that the size (H) of the magnetic field of the antenna 100 for short-range communication is 1.5 A / m < | H | &Lt; 7.5 A / m, the frequency detuning phenomenon can be suppressed as much as possible.

5 is a view for explaining a magnetic field change according to the number of turns (turn number) of a plurality of loop patterns included in the second conductive pattern in the antenna for short-range communication according to the present invention.

5A shows the case where the number of revolutions of the loop pattern included in the second conductive pattern P2 is one, FIG. 5B shows the case where the number of revolutions of the loop pattern included in the second conductive pattern P2 is two, (c) shows the case where the number of revolutions of the loop pattern included in the second conductive pattern P2 is three, (d) shows the case where the number of revolutions of the loop pattern included in the second conductive pattern P2 is four, 100 in accordance with the distance between the magnetic field and the magnetic field.

5, when the number of rotations of the loop pattern increases from one to four, the magnetic field of the second conductive pattern P2, which is generated in a direction opposite to the magnetic field generated in the first conductive pattern P1, gradually increases It can be seen that the magnetic field according to the distance of the antenna for short-range communication gradually decreases and the amount of decrease of the magnetic field increases as the distance from the antenna for short-range communication 100 approaches.

It can be seen that the magnetic field reduction amount of the antenna for short-range communication 100 becomes larger when the distance to the antenna for short-range communication 100 is 20 mm or less.

FIGS. 6 to 8 are diagrams for explaining the difference in the frequency detuning phenomenon according to the present invention and the comparative example.

6 (a) shows a case where two short-range communication antennas 100 according to a comparative example are located close to each other, and Figs. 7 (a) to 7 (d) A reflection loss S11 and a power transmission rate S21 according to the distance D1 between the two antennas for short-range communication 200A and 200B are measured.

6 (b) shows a case where two antennas 100 for short-range communication according to the present invention are located close to each other, and FIGS. 8 (a) to 8 (d) A reflection loss S11 and a power transmission rate S21 according to the distance D2 between the two antennas for short-range communication 100A and 100B are measured.

7 and 8, S11 (single) means the reflection loss S11 when the antenna for short-range communication 100 operates normally, and it can be confirmed that the minimum is the resonance frequency W0. S11 denotes a return loss when two short-range communication antennas 100 are adjacent to each other, and S21 denotes a power transmission rate S21 between two short-range communication antennas 100. [ Here, the case where the resonance frequency Wo is 13.56 MHz is an example.

The above-described frequency detuning phenomenon may occur most greatly when two near-field communication antennas having the same pattern are close to each other.

Therefore, in FIGS. 6A and 6B, the case where the near-field communication antennas 100 adjacent to each other have the same pattern is described as an example.

First, as shown in Fig. 6A, when two near-field (D1) communication antennas 200A and 200B without the second conductive pattern P2 are located close to each other, as shown in Fig. 7 Likewise, as the distance D1 between the two near-field (D1) communication antennas 200A and 200B approaches, the minimum reflection loss S11 frequency is separated in the direction away from the resonance frequency Wo, The power transmission rate S21 at the resonance frequency Wo greatly decreases while the maximum power transmission rate S21 is also separated in the direction away from the resonance frequency Wo, The frequency detuning phenomenon in which the operating frequencies of the antennas 200A and 200B are separated and moved becomes very large.

More specifically, in FIG. 7, the distance D1 between the two antennas 200A and 200B according to the comparative example is 10 mm, 20 mm, 30 mm, 40 mm.

In this case, when the distance D1 between the two antennas 200A and 200B according to the comparative example is 40 mm, the return loss S11 is the largest at the resonance frequency Wo as shown in FIG. 7 (d) And the power transmission rate S21 is the highest.

However, when the distance D1 between the two antennas 200A and 200B according to the comparative example is reduced to 40 mm ==> 30 mm ==> 20 mm ==> 10 mm, It can be seen that the return loss S11 at the resonant frequency Wo is significantly increased and the frequency at which the return loss S11 is minimum is separated from the resonant frequency Wo and separated from the resonant frequency Wo, It can be seen that the power transmission rate S21 at the resonance frequency Wo is greatly lowered while the frequency at which the maximum frequency S21 is also far from the resonance frequency Wo and separated.

Therefore, when the distance D1 between the two antennas 200A and 200B according to the comparative example is 10 mm, the width DF1 between the two frequencies, in which the return loss S11 is the minimum and the power transmission rate S21 is the maximum, It can be seen that the difference between the 12.3 MHz and the 16.3 MHz is 4 MHz, and the difference (DM1) between the maximum and minimum values of the power transmission rate (S21) is also very large, approximately 8 dB. As a result, the power transmission rate S21 at the resonance frequency Wo is very low and the return loss S11 is very high, so that it is possible to confirm that the near-field communication antennas 200A and 200B are in a very difficult state to operate normally.

As a result, as the distance D1 between the two antennas 200A and 200B according to the comparative example approaches, the frequency detuning (detuning) in which the operating frequencies of the antennas 200A and 200B for short- ) Phenomenon is very large.

However, as shown in Fig. 6 (b), when the two short-range communication antennas 100A and 100B having the second conductive pattern P2 are located close to each other according to the present invention, Likewise, as the distance D2 between the two short-range communication antennas 100A and 100B approaches, the minimum reflection loss S11 frequency is separated in the direction away from the resonance frequency Wo, but the width DF2 thereof is not large , It can be confirmed that the amount of decrease in the reflection loss S11 at the resonance frequency Wo is not large.

In addition, although the maximum power transmission rate S21 is also separated in the direction away from the resonance frequency Wo, the frequency separation width DF2 is not large and the power transmission rate S21 at the resonance frequency Wo is reduced. However, DM2) is not large.

Accordingly, it can be seen that the frequency detuning phenomenon in which the operating frequencies of the antennas 100A and 100B for short-distance communication are separated and moved is greatly suppressed.

More specifically, in FIG. 8, the distance D2 between the two antennas according to the present invention is 10 mm, (b) 20 mm, (c) 30 mm and (d) 40 mm.

Here, when the distance D2 between the two antennas 100A and 100B according to the present invention is 40 mm, as shown in FIG. 8 (d), the return loss S11 at the resonance frequency Wo becomes And the power transmission rate S21 is the highest.

If the distance D2 between the two antennas 100A and 100B according to the present invention is reduced to 40 mm ==> 30 mm ==> 20 mm ==> 10 mm, As shown in the drawing, the frequency at which the reflection loss S11 at the resonance frequency Wo is relatively small and the reflection loss S11 is the minimum is separated from the resonance frequency Wo and separated from the resonance frequency Wo, ) Is relatively small.

Although the frequency at which the power transmission rate S21 is the maximum is also separated and separated from the resonance frequency Wo, the frequency separation width DF2 is relatively small and the power transmission rate S21 at the resonance frequency W0 ) Is also relatively suppressed.

Therefore, when the distance D2 between the two antennas according to the present invention is 10 mm, the width DF2 between the two frequencies in which the return loss S11 is the minimum and the power transmission rate S21 is the maximum is 13 MHz and 14.7 MHz And the difference DM2 of the maximum minimum value of the power transmission rate S21 is also about 2.5 dB or less, which is less than half of the frequency separation width DF1 shown in FIG. 7 (a) Which is very small.

Accordingly, when the distance D2 between the two antennas 100A and 100B according to the present invention is 10 mm, the power transmission rate S21 at the resonance frequency Wo is relatively high, and the return loss S11 is It can be confirmed that the near-field communication antennas 100A and 100B can operate normally.

Accordingly, as the distance D2 between the two antennas approaches the distance D2 between the two antennas according to the present invention, the operating frequencies of the antennas 100A and 100B for short- It can be confirmed that the frequency detuning phenomenon is greatly suppressed.

9 is a diagram for explaining a difference in power transmission rate according to the present invention and a comparative example.

9A is a graph showing a power transmission rate S21 according to the distance D1 of the antennas 100A and 100B for short-range communication according to the present invention. FIG. 9B is a graph showing the power- , And 200B in accordance with the distance D2.

9, in the case of the comparative example, when the distance D2 is 15 mm or more and 50 mm or less with the antennas 200A and 200B for short distance communication, a proper power transmission rate S21 is maintained between -5dB and -12dB It can be confirmed that the power transmission rate S21 is greatly lowered when the distance D2 from the antennas 200A and 200B for short distance communication is 15 mm or less.

However, in the case of the present invention, even when the distance D1 is 15 mm or more and 50 mm or less, as well as 15 mm or less, the power transmission rate S21 of an appropriate level is maintained between -5 dB and -12 dB .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (11)

An FR-4 substrate, which is a dielectric substrate containing ferrite as a magnetic material for shielding or reflecting electromagnetic waves and whose dielectric constant (epsilon r) is between 3.0 and 5.0, and which is made up of multiple layers of glass fiber impregnated with epoxy resin A base substrate;
A first conductive pattern disposed on one surface of the base substrate in a loop pattern and having both ends of the loop pattern connected to an antenna feeding portion; And
And a second conductive pattern formed on one surface of the base substrate and surrounded by the first conductive pattern and spaced apart from the first conductive pattern and formed in a loop pattern,
An impedance matching portion is provided at an end of the first conductive pattern adjacent to the antenna feeding portion for impedance matching between the first conductive pattern P1 and the antenna circuit. The impedance matching portion includes a plurality of capacitor elements Wherein the first conductive pattern is formed in a pattern having a plurality of loops in order to reduce an area of the antenna while securing a resistance value, a capacitance value, and an inductance value of the antenna, the loop pattern included in the first conductive pattern,
Wherein a direction of a current flowing through the second conductive pattern is opposite to a direction of a current flowing through the first conductive pattern and a current flowing through the second conductive pattern is induced by a current flowing in the first conductive pattern, The magnetic field H generated in the second conductive pattern and the magnetic field H generated in the first conductive pattern are canceled due to the phases of the different electric currents so that the size H of the magnetic field in the adjacent area can be reduced, (NFC) antenna for suppressing a frequency detuning phenomenon in which the operating frequency of the antenna for short-range communication is separated and moved when the antennas for short-range communication are close to each other. delete delete The method according to claim 1,
The plurality of loop patterns included in the first conductive pattern are connected to each other, and the plurality of loop patterns included in the first conductive pattern are connected to each other,
Wherein the plurality of loop patterns included in the second conductive pattern are plural and the plurality of loop patterns included in the second conductive pattern are not connected to each other and are spaced apart from each other. 5. The method of claim 4,
And the number of revolutions of the second conductive pattern is between 2 times and 6 times. 5. The method of claim 4,
The distance between the first conductive pattern and the second conductive pattern is
In order to prevent the transmission / reception ratio of the signal from being lowered so as not to affect the resonance frequency (Wo) value of the first conductive pattern (P1) determined by the resistance value, the capacitance value and the inductance value, Wherein the distance between the loop patterns of the second conductive pattern is larger than the distance between the loop patterns of the second conductive pattern. The method according to claim 6,
Wherein a width of each of the loop patterns in the first conductive pattern is the same as an interval between the respective loop patterns in the first conductive pattern and equal to a width of each loop pattern in the second conductive pattern,
Wherein the width of each loop pattern in the second conductive pattern is equal to the interval between the respective loop patterns in the second conductive pattern. delete delete The method according to any one of claims 1 to 7,
A short range communication device comprising a short range communication antenna according to any one of the first, second, and fourth to seventh aspects. delete

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