KR20200088151A - On board antenna for miniaturization terminal - Google Patents

Abstract

The present invention relates to an on-board antenna for a small terminal. According to one embodiment of the present invention, the on-board antenna for a small terminal comprises a mu zero resonator (MZR) cell, which operates in a 2.4 GHz Wi-Fi band, only in a condition which has a PCB having the length, width, and thickness of 78 × 38 × 0.8 mm^3, a system region having the length, width, and thickness of 63 × 38 × 0.8 mm^3, and a radiation unit configured in the PCB having the length, width, and thickness of 15 × 38 × 0.8 mm^3. Accordingly, not only can the antenna be miniaturized, which can be easily applied to a small terminal, but also a wide operating bandwidth and single radiation characteristic can be easily satisfied.

Description

ON BOARD ANTENNA FOR MINIATURIZATION TERMINAL

The present invention relates to an antenna. More specifically, it relates to an on-board antenna for application to a portable wireless device.

For example, by using various portable wireless devices, an antenna having a high efficiency and a small size is needed to improve RF characteristics, and as a result, antenna miniaturization technology is attractive and ongoing research is ongoing.

Research on miniaturization of antennas is an important research field in the introduction of high-speed communication, medical applications of microwave signals, wearable antennas for telemedicine, and short-range communication for Internet access.

From the system designer's point of view, system design using a small antenna structure is a very good idea, but from the antenna designer's point of view, it meets all the necessary criteria including miniaturization of the antenna, wide operating bandwidth (BW), and single radiation characteristics. It is a very difficult situation.

This is because the antenna size and radiation characteristics are theoretically limited by complementary characteristics. The cause of this limiting factor is mainly due to the quality factor of the antenna, and in the case of a linearly polarized antenna, the bandwidth is due to a property inversely proportional to the antenna size.

Therefore, by reducing the antenna size, the quality factor increases while the bandwidth of the antenna decreases.

In order to overcome this theoretical problem, a metamaterial structure has been recently proposed. For example, these structures, called NRI (Negative Refractive Index) transmission line (TL) or Composite Right Left Handed (CRLH), can be configured by adding serial capacitance and shunt inductance to the transmission line and the antenna radiating portion.

In addition, the antenna configured in this way can change the antenna radiation characteristics by using backward wave popagation and zero propagation characteristics that resonate regardless of the length, which cannot be obtained in a conventional transmission line.

Therefore, the antenna resonance point can resonate regardless of the size of the antenna, and various antennas using this technology have been proposed and applied to the miniaturization of the antenna.

However, the small antenna according to the prior art has disadvantages such as low gain, efficiency, and narrow bandwidth, which are important characteristics of the antenna, and efforts to improve characteristics by using an antenna and an emitter with metamaterial to solve these disadvantages Is doing.

Republic of Korea Patent Publication No. 10-2018-0053862

The miniaturization of the antenna uses a ZOR (Zero order resonator) having an infinite wavelength among the characteristics of CRLH metamaterial. Using this concept, it can be constructed using EZR (Epsilon Zero Resonator) using zero-order resonance mode and MZR (Mu Zero Resonator) using only series capacitance using only parallel inductance.

This ZOR has the advantage that a very small antenna configuration is possible because the resonance frequency is not affected by the size of the antenna, and an antenna configuration that is not influenced by the outside is possible by forming a uniform electric field between the ground plane and the antenna. The radiation pattern of the antenna is omnidirectional.

An object of the present invention is to provide an on-board antenna for a small terminal that can be easily applied to portable wireless devices using MZR operating in the 2.4 GHz Wi-Fi band.

In order to solve the above problem,

On-board antenna for a small terminal according to an embodiment of the present invention is a PCB (Printed Circuit Board);

Including,

The length, width, and thickness of the PCB are 78×38×0.8㎣, and the length, width, and thickness of the system area constituting the PCB are 63×38×0.8㎣, and the length and width of the radiating portion constituting the PCB, The thickness is 15 × 38 × 0.8㎣ MZR (Mu Zero Resonator) cell operating in the 2.4GHz Wi-Fi (WiFi) band only in the limited condition;

It includes,

The MZR cells are arranged in the longitudinal direction at intervals.

In addition, in the on-board antenna for a small terminal according to an embodiment of the present invention, a feeding point is configured at a top of one side of the system area, and a CPW structure is used for stable feeding in the system area. Is done.

In addition, in the on-board antenna for a small terminal according to an embodiment of the present invention, the coupling between the feeder and the PCB uses a magnetic field coupling structure.

In addition, in the on-board antenna for a small terminal according to an embodiment of the present invention, both sides of the radiating section for the MZR cell configuration are constructed using a strip line having a line width of 0.1 mm and a length of 6 to 8 mm. do.

These solutions will become more apparent from the specific details for carrying out the following invention based on the accompanying drawings.

Prior to this, the terms or words used in the specification and claims should not be interpreted in a conventional and lexical sense, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle of being able to be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

According to an embodiment of the present invention, it is configured by using an MZR cell operating in the 2.4GHz Wi-Fi (WiFi) band only under limited conditions, so that the on-board antenna can be miniaturized and easily applicable to a small terminal. Wide operating bandwidth and single radiation characteristics can be easily met.

,

에서 이론값과 실험값의 비교도면.
도 11은 본 발명의 일실시 예에 따른 소형 단말기용 온 보드 안테나의

에서 방사 패턴의 측정값을 나타내 보인 도면.1 is a view showing a transmission line model of the MZR cell according to an embodiment of the present invention.
2 is a structural diagram of an on-board antenna for a small terminal according to an embodiment of the present invention.
3 is a structural view showing a radiating portion of the on-board antenna for a small terminal according to an embodiment of the present invention.
4 is a view showing a reflection loss characteristic by changing the spacing between MZR cells according to an embodiment of the present invention.
5 is a view showing the reflection loss characteristics according to the length change of the MZR cell according to an embodiment of the present invention.
6 is a view showing a reflection loss characteristic according to an interdigital length change according to an embodiment of the present invention.
7 is a view showing the reflection loss characteristics according to the distance between the ground plane and the radiating unit according to an embodiment of the present invention.
Figure 8 is a real picture showing the on-board antenna for a small terminal according to an embodiment of the present invention as a whole.
9 is a view showing a return loss measurement value of the on-board antenna for a small terminal according to an embodiment of the present invention.
10 is an on-board antenna for a small terminal according to an embodiment of the present invention

,

In the drawing comparing the theoretical and experimental values.
11 is an on-board antenna for a small terminal according to an embodiment of the present invention

In the drawing showing the measured value of the radiation pattern.

The specific aspects and specific technical features of the present invention will become more apparent from the following specific contents and embodiments associated with the accompanying drawings. It should be noted that in this specification, when adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing an embodiment of the present invention, when it is determined that detailed descriptions of related known configurations or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, the component may be directly connected to or connected to the other component, but another component between each component It should be understood that elements may be "connected", "coupled" or "connected".

First, in the on-board antenna for a small terminal according to an embodiment of the present invention, the length, width, and thickness of a printed circuit board (PCB) are 78×38×0.8㎣, and the length, width, The thickness is 63×38×0.8㎣, and the length, width, and thickness of the radiating portion formed on the PCB are MZR (Mu Zero Resonator) cells operating in the 2.4GHz Wi-Fi band only under the constraints of 15×38×0.8㎣. It includes.

와 셀의 인덕턴스

에 의해서 결정되므로, 셀 사이의 간격, 셀의 길이, 인터디지털 캡(Interdigital Cap)의 길이, 방사부와 접지면의 간격에 대하여 분석하였으며, 그 결과를 사용하게 된다.The resonance frequency of the MZR is a series capacitor

And cell inductance

Since it is determined by the distance between the cells, the length of the cell, the length of the interdigital cap (Interdigital Cap), the distance between the radiating section and the ground plane was analyzed, and the result is used.

×0.072

×0.0064

이다. 그리고 측정결과 10dB 대역폭, 이득과 방향성은 각각 440MHz(18.3%), 0.4405dB, 2.722dB이다. 방사 패턴은 전방향 특성이 있다.The on-board antenna for the small terminal has a length, width, and thickness of 20.8×9.0×0.8㎣ including a feeding structure, and an electrical length of 0.1664

×0.072

×0.0064

to be. And the measurement results show that the 10dB bandwidth, gain and directionality are 440MHz (18.3%), 0.4405dB, and 2.722dB, respectively. The radiation pattern is omnidirectional.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a transmission line model of an MZR cell according to an embodiment of the present invention, and can be expressed as (a) and (b) using a distributed integer circuit and a concentrated integer circuit, and periodic boundary conditions The exact variance applied by can be expressed as follows.

[Equation 1]

는 전송선로의 전기적인 길이이며,

이다.here

Is the electrical length of the transmission line,

to be.

)고 가정하면 [식2]는 다음과 같다.Also, it is assumed that the size of the parallel inductor is infinite, and the cell size is small (

Assuming ), Equation 2 is as follows.

[Equation 2]

는 직렬부하 커패시터이고,

,

은 전송선로의 단위길이당 커패시터와 인덕터이고,

는 전파상수이고,

는 전송선로의 특성임피던스이다.here

Is a series load capacitor,

,

Is the capacitor and inductor per unit length of the transmission line,

Is the propagation constant,

Is the characteristic impedance of the transmission line.

Assuming that the cell size is infinitely small, the propagation constant of MZR is as follows.

[Equation 3]

와 전송선로의 직렬 인덕턴스를 조합함으로써 전파상수가 영인 공진 조건을 얻을 수 있으며, 이를 영차공진(Zeroth order resonance)이라 한다.By analyzing the above [Equation 3] in detail, it can be intuitively understood that the propagation constant can have a zero value at an arbitrary frequency. I.e. inserted in series

By combining the series inductance of and transmission line, the resonance condition of zero propagation constant can be obtained, and this is called zero order resonance.

The condition in which resonance of the MZR transmission line occurs can be expressed as follows.

[Equation 4]

Here, N is the number of cells, and therefore a resonance point can be obtained in a positive mode.

The MZR resonant frequency uses open and short conditions for the termination of the general transmission line. At this time, when the termination is open, the input input impedance is

[Equation 5]

, And the input impedance in the shorted condition,

[Equation 6]

to be.

When this condition is applied to FIG. 1, [Equation 5] and [Equation 6] are derived as follows.

Input impedance under load open condition,

[Equation 7]

And input impedance under load short circuit condition,

[Equation 8]

It becomes.

If the MZR resonance frequency is obtained using [Equation 8],

[Equation 9]

to be.

Therefore, it can be confirmed that the resonant frequency is independent of the length of the resonator.

은 63㎜, 상기 PCB(2)의 상부에 구성되는 방사부(10) 크기인

는 15㎜이다. FR4 재질로 이루어지는 PCB(2)는 상대 유전율이 4.4, 두께가 0.8㎜인 제한조건에서 2.45 GHz 와이파이(WiFi) 대역에서 공진하는 온 보드 안테나를 구성하게 된다.In FIG. 2, the size of the system area 20 configured under the PCB 2 is W=38 mm,

Is 63 mm, which is the size of the radiating part 10 formed on the upper part of the PCB 2

Is 15 mm. The PCB 2 made of FR4 material constitutes an on-board antenna that resonates in the 2.45 GHz Wi-Fi band under the condition that the relative permittivity is 4.4 and the thickness is 0.8 mm.

를 사용하고 있으나 소형 단말기의 제한조건으로 인하여 CPW의 크기는 11㎜,

=2.5㎜로 실시하였다. MZR 셀 구성을 위한 방사부(10)의 양면 단락은 스트립선로를 사용하며, 선로폭

은 0.1㎜로 실시하게 된다.The configuration of the on-board antenna in FIG. 3 includes two MZR cells arranged in the longitudinal direction with an interdigital cap formed in the longitudinal direction, and in general, the feeding line of the feeding unit 30 for matching is 0.25

The size of CPW is 11mm, due to the restrictions of the small terminal.

= 2.5 mm. The short circuit on both sides of the radiating section 10 for the MZR cell configuration uses a strip line, and the line width

Is carried out at 0.1 mm.

와 셀의 인덕턴스

에 의해서 결정됨을 알 수 있다. 즉 직렬 커패시턴스는 셀의 폭과 인터디지털 캡의 구조에 의해서 형성되며, 인덕턴스는 선로의 폭과 길이에 의해서 결정됨을 알 수 있다.According to [Equation 9], the resonance frequency of MZR is a series capacitor

And cell inductance

It can be seen that is determined by. That is, it can be seen that the series capacitance is formed by the width of the cell and the structure of the interdigital cap, and the inductance is determined by the width and length of the line.

It can be seen that it is reasonable to determine the resonance frequency using the above two conditions for the antenna miniaturization design.

Therefore, in the present invention, the gap between the MZR cell, the length of the MZR cell, the length of the interdigital cap, the spacing between the radiating part and the ground plane, which can cause a change in the series capacitor and the series inductance, were analyzed, and the results of the analysis are shown in FIG. 4. Same as

는 5㎜,

는 8㎜,

은 2㎜,

은 2㎜일 때 MZR 셀 사이의 간격변화에 따른 반사손실을 나타내고 있다. MZR 셀 간격

가 0.2㎜, 0.3㎜, 0.4㎜일 때 각각 최대 반사손실이 발생하는 공진 주파수가 2.6865GHz, 2.7261GHz, 2.6072GHz로 감소하고, 반사손실이 개선됨을 확인할 수 있으며, 이것은 간격이 증가함으로써

가 감소함을 알 수 있다.Figure 4

Is 5㎜,

Is 8㎜,

2 mm,

Indicates the return loss due to the change in spacing between MZR cells at 2 mm. MZR cell spacing

When is 0.2㎜, 0.3㎜, 0.4㎜ respectively, the resonance frequency at which maximum reflection loss occurs decreases to 2.6865GHz, 2.7261GHz, 2.6072GHz, and it can be seen that reflection loss is improved.

It can be seen that decreases.

를 0.4㎜로 설정하고, MZR 셀의 길이

을 4㎜, 5㎜, 6㎜로 변화시켰을 때 각각 최대 반사손실이 발생하는 공진 주파수가 2.6171GHz, 2.6072GHz, 1.6559GHz로 감소하고, 반사손실과 대역폭이 변화됨을 확인할 수 있으며, 이것은 MZR 셀의 길이가 증가함으로

이 증가로 인한 결과이다.Figure 5 is the MZR cell spacing in the condition of Figure 4

Is set to 0.4 mm, and the length of the MZR cell

When 4 is changed to 4 mm, 5 mm, and 6 mm, the resonance frequencies at which maximum reflection loss occurs respectively are reduced to 2.6171 GHz, 2.6072 GHz, and 1.6559 GHz, and it can be seen that reflection loss and bandwidth are changed. As the length increases

This is the result of the increase.

를 0.4㎜로 설정하고, 인터디지털 캡의 길이

을 0.2㎜, 0.6㎜, 1㎜로 변화시켰을 때 각각 최대 반사손실이 발생하는 공진 주파수가 2.6072GHz, 2.7221GHz, 2.7162GHz로 증가하고, 반사손실과 대역폭이 변화됨을 확인할 수 있으며, 이것은 인터디지털 캡의 길이가 증가함으로써 생성되는 인덕턴스와 커패시터의 상쇄로 인하여 길이 증가로 인한 공진주파수의 변화가 적음을 알 수 있다.Figure 6 is in the condition of Figure 4

Is set to 0.4 mm, and the length of the interdigital cap

When the values were changed to 0.2㎜, 0.6㎜, and 1㎜, the resonance frequencies at which the maximum reflection loss occurred respectively increased to 2.6072GHz, 2.7221GHz, and 2.7162GHz, and it was confirmed that the reflection loss and bandwidth were changed. It can be seen that the change in resonant frequency due to the increase in length is small due to the cancellation of the inductance and capacitor generated by the increase of the length of.

를 0.4㎜로 설정하고, 접지면과 방사부의 간격 길이

를 6㎜, 7㎜, 8㎜로 변화시켰을 때 각각 최대 반사손실이 발생하는 공진 주파수가 2.8252GHz, 2.6865GHz, 2.6072GHz로 감소하고 있으며, 반사손실과 대역폭이 변화됨을 확인할 수 있으며, 이것은 접지면과 방사부의 길이가 증가함으로써 급전선의 길이가 증가함으로 인한 입력 임피던스의 변화에 따른 공진주파수가 변화됨을 알 수 있다.Figure 7 is in the condition of Figure 4

Is set to 0.4 mm, the distance between the ground plane and the radiating section

When changing to 6㎜, 7㎜, 8㎜, the resonant frequency at which maximum reflection loss occurs respectively is decreased to 2.8252GHz, 2.6865GHz, 2.6072GHz, and it can be seen that reflection loss and bandwidth are changed, which is the ground plane. It can be seen that the resonance frequency is changed according to the change in the input impedance due to the increase in the length of the feeder line as the length of the over-radiation section increases.

,

에 따라서 온 보드 안테나의 공진주파수를 변화시킬 수 있음을 확인하였다. 따라서 공진기의 폭과 인터디지털 커패시턴스를 형성시킬 수 있는 인터디지털 캡의 변화에 따라서 온 보드 안테나의 공진주파수를 변화시킬 수 있다.What can be inferred from the results of FIGS. 4 to 7

,

Accordingly, it was confirmed that the resonance frequency of the on-board antenna can be changed. Therefore, the resonance frequency of the on-board antenna can be changed according to the change of the width of the resonator and the interdigital cap capable of forming the interdigital capacitance.

[Experimental Example]

In the on-board antenna composed of two MZR cells specified in the present invention, the resonance point, which is an important characteristic of the on-board antenna according to the distance, the length of the MZR cell, the length of the interdigital cap, and the length between the radiating part and the ground plane, , It was analyzed about the improvement of return loss and matching.

Parameters Quantity Parameters Quantity

4.0

0.1

4.0

2.5

0.6

0.1

0.8

4.0

5.0

0.3

0.5

Design value of on-board antenna (Unit: mm)

Using the analysis data for these, the length, width, and thickness of the PCB are 78×38×0.8,, the length, width, and thickness of the system area constituting the PCB is 63×38×0.8㎣, and the length of the radiating part, The width and thickness are 15×38×0.8㎣, and the on-board antenna was constructed using two MZR cells operating in the 2.4GHz Wi-Fi band only under the constraints using FR4 as the material of the PCB.

×0.072

×0.0064

이다.The feeding structure is limited to the upper left of the system area in the drawing, and the on-board antenna is designed and manufactured, and the on-board antenna is shown in FIG. 8. The length, width, and thickness of the antenna including the feeding structure are 20.8×9.0×0.8㎣, and when converted to electrical length, 0.1664

×0.072

×0.0064

to be.

으로 설정하였으며, CPW의 임피던스가 같도록 설계하였다.8 is an actual on-board antenna manufactured based on the theory proposed in the present invention. [Table 1] shows values for the parameters presented in FIG. 3. The impedance of the feeder

It was set as and designed to have the same impedance of CPW.

Item Theory value Experiment value Band width 2.3595~2.7757 GHz
0.4162 GHz (17.3 %) 2.3116~2.7521 GHz
0.4405 GHz (18.3 %) Gain 5.9197 dB 0.377802 dB Directivity 3.8992 dB 2.72213 dB

[Table 2] tested the return loss and radiation characteristics of the on-board antenna manufactured using the ZVA40 (Rohde & Schwarz) network analyzer and the OTA radiation pattern meter owned by the Gumi Institute of Electronic Information Technology, respectively. It is the same as 11 to 11, and compares the theoretical value and the experimental value for the on-board antenna measurement items.

9 to 11 is a comparison of the theoretical value and the experimental value of the return loss and radiation pattern of the on-board antenna for a small terminal according to an embodiment of the present invention at 2.40GHz, the resonance point from the return loss result is the theoretical value And the experimental values were confirmed to be the same.

As a result of the experiment, the 10dB bandwidth and gain are 440 MHz (18.3%) and 0.4405dB, respectively. The error between the theoretical value and the experimental value of the produced antenna was found to be 30MHz, 5.6dB, and 1.1dB at 2.4GHz.

In particular, the bandwidth and the directionality were small, but there were many errors in gain. This error is thought to be due to the error between simulation and measurement. In other words, it takes about 80 mm for the coaxial cable to measure, which is thought to be the result of errors due to cable and experimental measurements.

The radiation pattern generally has an omnidirectional characteristic, and was measured to have superior characteristics of about 5 dB in the lateral direction than in the anterior and posterior directions.

Therefore, it can be confirmed that it is applicable to an on-board antenna for a small terminal using two MZR cells specified in the present invention.

The present invention has been described in detail through an embodiment, but this is for specifically describing the present invention, and the on-board antenna for a small terminal according to the present invention is not limited thereto. In addition, the terms "include", "consist", or "have" as described above mean that the corresponding component can be inherent unless specifically stated to the contrary, excluding other components However, it should be interpreted as being able to further include other components, and all terms, including technical or scientific terms, are generally understood by those skilled in the art to which the present invention pertains, unless otherwise defined. It has the same meaning as being.

In addition, the above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains can variously modify and modify the scope without departing from the essential characteristics of the present invention. Therefore, the exemplary embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain the scope, and the scope of the technical spirit of the present invention is not limited by the exemplary embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

1: MZR cell 2: PCB
10: radiating section 20: system area
30: feeder

Claims (5)

PCB (Printed Circuit Board);
Including,
The length, width, and thickness of the PCB are 78×38×0.8㎣, and the length, width, and thickness of the system area constituting the PCB are 63×38×0.8㎣, and the length and width of the radiating portion constituting the PCB, MZR (Mu Zero Resonator) cells operating in the 2.4GHz Wi-Fi band only under the condition of 15×38×0.8㎣;
It includes,
The MZR cell is an on-board antenna for a small terminal arranged in a longitudinal direction at a distance.
The method according to claim 1,
The PCB is made of FR4 material, the on-board antenna for a small terminal having a relative permittivity of 4.4.
The method according to claim 1,
An on-board antenna for a small terminal in which a feeding point of a feeding part is configured at one upper end of the system area.
The method according to claim 1,
The on-board antenna for a small terminal constructed by using a strip line having a line width of 0.1 mm and a length of 6 to 8 mm in both sides of the radiating section for the MZR cell configuration.
The method according to claim 4,
The width of the MZR cell is 5 mm, the length is 2 to 6 mm, the length of the interdigital cap formed in the longitudinal direction of the MZR cell is 0.2 to 2 mm, and the distance between the two MZR cells is 0.2 to 0.4 mm. On-board antenna for small terminal.

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