CN101964450A - Antenna of hand-held device - Google Patents

Abstract

The present invention relates to an antenna structure, and in particular to an antenna structure for a handheld device. The antenna structure of the present invention is a continuous transmission line, and forms a ring shape from the outside to the inside, and has two endpoints, the first endpoint is a free end, and the second endpoint is electrically connected to a ground end. In addition, there is a signal feeding point for the antenna signal to be fed into the antenna structure, wherein the signal feeding point is electrically connected to the continuous transmission line and is two-thirds of the wavelength away from the second endpoint. According to the antenna structure of the present invention, a miniaturized antenna structure can be provided, and can operate in an ultra-wideband frequency band, and can simultaneously receive and transmit signals in multiple frequency bands. In addition, according to the antenna structure of the present invention, it can have a lower high-order harmonic signal strength, thereby preventing the antenna signal from being interfered with by high-order harmonics.

Description

Antennas for Handheld Devices

technical field

The invention relates to an antenna design, especially an antenna design suitable for a handheld device.

Background technique

Due to the advancement of technology, various high-tech electronic products have been developed to facilitate people's life, including various electronic devices, such as notebook computers, mobile phones, personal digital assistants (PDAs), and the like. With the popularization of these high-tech electronic products and the increase of people's needs, in addition to the substantial increase in the functions and applications configured in these high-tech products, especially in order to meet people's mobile needs, the function of wireless communication has been added. . Therefore, people can use these high-tech electronic products at any place or at any time through these high-tech electronic devices with wireless communication functions. Thereby greatly increasing the flexibility and convenience of the use of these high-tech electronic products, therefore, people no longer have to be confined to a fixed area, breaking the boundaries of the scope of use, making the application of these electronic products really convenient people's lives.

As the applicability of these electronic products increases, people have higher and higher requirements for various applications, especially the use of these electronic products in various frequency bands. Therefore, in these electronic products, a dual-band or triple-band antenna structure is usually provided to meet the requirements for transceiving and operating in various frequency bands. In order to still obtain good sending and receiving signals in different environments, the design and quality of these antennas need to be precisely designed.

In general, known antennas usually include Dipole Antenna, Monopole Antenna, Patch Antenna, Planar Inverted-F Antenna, Meander Line Antenna Antenna), Inverted-L Antenna, Loop Antenna, Spiral Antenna, Spring Antenna, etc. Therefore, these antennas usually have a relatively large area, and occupy a relatively large space for various electronic devices, which increases the volume of these electronic devices. However, the main purpose of the design and development of these electronic devices is to allow users to carry them easily. Therefore, how to reduce the size of the antenna will be a problem that these electronic devices need to overcome.

In addition, because the generally known antennas usually have higher signal strength of second or third harmonics, or other higher harmonics, these higher harmonics will cause interference in wireless signal transmission and reception, and will indirectly interfere with Other electronic devices utilizing wireless transmission and wireless communication. The safety standard certification formulated by the Federal Communications Commission (FCC) of the United States also stipulates the value of the high-order harmonic interference that these antennas should have. In addition, the safety standards of various countries also have this Higher harmonics have a limit value. Therefore, since the commonly known antennas have higher signal strength of higher harmonics, if these known antennas are used in these electronic products, they will fail to pass the certification test in the safety standard certification of various countries. This will cause these electronic products to fail to pass the certification and cannot be sold. Therefore, how to reduce the signal strength of the high-order harmonics of these antennas has also become a problem that these electronic products need to overcome.

Contents of the invention

The invention provides an antenna with a miniaturized structure, which is manufactured by using a microstrip line and has a surrounding structure, which can reduce the required area of the antenna.

The present invention provides a miniaturized antenna, which has a surrounding structure, which can make the antenna with this structure have a lower high-order harmonic signal strength, so that it can avoid the interference of high-order harmonics when sending and receiving signals, and can avoid indirect Interfere with other electronic devices that use wireless transmission and wireless communication.

The invention provides an antenna structure, which can transmit/receive ultra-wideband antenna signal frequency bands, and can provide multi-band operation.

According to an embodiment of the present invention, an antenna structure is provided, which is characterized in that: a continuous transmission line forms a surrounding structure from outside to inside, which has a first end point and a second end point, and the first end point is a A free end, the second end point is electrically connected to a ground end; a signal feeding point is electrically connected to the continuous transmission line, and the distance from the second end point is 2/3 of the wavelength.

The inventive concept proposed in this application, the mechanism of the present invention is completely different from the known technology, in order to provide an antenna structure with low-intensity high-order harmonics and suitable for multi-band operation, so as to promote industrial upgrading.

The above overview, the following detailed description and accompanying drawings are all for further illustrating the ways, means and effects of the present invention to achieve the intended purpose. Other purposes and advantages of the present invention will be described in the subsequent description and accompanying drawings.

Description of drawings

Figure 1 shows a schematic diagram of the antenna structure according to the present invention;

FIG. 2 is a diagram illustrating the measurement of the frequency response of the reflection loss according to the first embodiment of the present invention;

FIG. 3 is a diagram showing the measurement of the frequency response of the reflection loss according to the second embodiment of the present invention;

FIG. 4 is a diagram showing the measurement of the frequency response of the reflection loss according to the third embodiment of the present invention;

FIG. 5 is a measurement illustration of a Smith Chart (Smith Chart) according to a third embodiment of the present invention;

FIG. 6 is a diagram illustrating the measurement of the frequency response of the reflection loss according to the fourth embodiment of the present invention;

FIG. 7 is a measurement illustration of a Smith Chart (Smith Chart) according to a fourth embodiment of the present invention;

Fig. 8 is a measurement illustration of the frequency response of the reflection loss according to the first embodiment of the present invention;

9 is a measurement illustration of a Smith Chart (Smith Chart) according to a first embodiment of the present invention;

FIG. 10 is a measurement illustration of electromagnetic wave interference in the vertical direction according to the first embodiment of the present invention;

FIG. 11 is a measurement illustration of electromagnetic wave interference in the horizontal direction according to the first embodiment of the present invention;

Fig. 12 is a measurement illustration in the vertical direction of electromagnetic wave interference of higher harmonics according to the first embodiment of the present invention;

FIG. 13 is a diagram illustrating the measurement of electromagnetic wave interference of higher harmonics in the horizontal direction according to the first embodiment of the present invention.

[Description of reference signs of main components]

10: Antenna structure

11: Substrate

12: First endpoint

13: Second endpoint

14: Signal feed-in endpoint

h: thickness

Detailed ways

Fig. 1 is a schematic diagram showing the structure of an antenna according to the present invention.

Please refer to Figure 1. FIG. 1 is a schematic structural diagram of an antenna structure 10 according to the present invention. The antenna structure 10 of the present invention is formed on a substrate 11, wherein the substrate 11 in the embodiment of the present invention is a standard FR4 glass fiber board with a dielectric constant ε _r of 4.4 and a thickness h of 1.2 mm. According to the spirit of the present invention, the substrate 11 can also be a glass fiber board of other specifications or the substrate 11 of other specifications, and the specification of the substrate 11 of the present invention is not limited thereto.

In addition, the antenna structure 10 has two terminals 12 , 13 , the first terminal 12 is a free terminal, and the second terminal 13 is electrically connected to a ground terminal. The antenna structure 10 of the present invention uses a continuous transmission line to form a surrounding structure from the outside to the inside. This surrounding structure can be a circle, a square, a triangle, an ellipse, or two semicircles as shown in Figure 1 and a long straight transmission line. ring, and the surrounding structure has multiple turns as shown in FIG. 1 to form the antenna structure 10 of the present invention. In addition, the antenna structure 10 has a signal feed point 14 for feeding the antenna signal.

Since the antenna structure 10 has a surrounding structure with multiple turns, and the distance between the continuous transmission lines can be the same distance, and the line width of the continuous transmission lines can also be the same, so it has an inductance characteristic, and can be easily adjusted by means of The spacing between successive transmission lines and the number of multi-turns further adjust the inductance value.

The signal feeding point 14 of the antenna structure 10 is a contact point, and the signal feeding point 14 is electrically connected to the continuous transmission line of the antenna structure 10 for feeding the signal into the antenna structure 10 . Wherein, the distance between the signal feeding point 14 and the second end point 13 of the antenna structure 10 needs to be two-thirds of the wavelength (2λ/3). That is, the distance between the signal feeding point 14 and the grounding point of the antenna structure 10 needs to be two-thirds of the wavelength (2λ/3). Therefore, when the antenna signal is fed into the antenna structure 10 from the signal feeding point 14, the antenna signal is transmitted to the first terminal 12 and the second terminal 13 at the same time, and is transmitted from the outside to the inside to the first terminal 12 in a radial direction. . Since the signal feeding point 14 of the antenna structure 10 is two-thirds of the wavelength (2λ/3) away from the ground point of the second end 13, it can have better inductance when the antenna signal is transmitted to the first end point 12 and resistance.

According to the embodiment of the present invention, it is proposed that the optimal line width and line spacing of the antenna structure 10 are respectively 0.2 mm, and the overall occupied area of the antenna structure 10 has a length of 29.3 mm and a width of 7.9 mm. The numerical value of the area occupied by the antenna structure 10 here is only a preferred embodiment, and is still related to the optimal transmission frequency, line length, line width, line distance, surrounding shape and the number of circles of the antenna structure 10 in fact. , even related to the parameters of the substrate 11. For example, when applied to different frequencies, the wire length will be adjusted accordingly. For example, the optical formula λ=C/F expresses the relationship between the wavelength (λ), the speed of light (C) and the frequency (F). For example, when the frequency is 434MHz, the wavelength is about 69 cm, and according to the shortest transmission line of the antenna needs to be a quarter of the wavelength (λ/4), the length of the transmission line of the antenna needs to be about 17.27 cm. In addition, the value of the area occupied by the antenna structure 10 as a whole is also related to the parameters such as the width of the transmission line and the distance between the transmission lines, etc., which will not be repeated here. Therefore, the area occupied by the antenna structure 10 disclosed here is only a preferred embodiment, and still needs to be optimized and adjusted according to actual design parameters. Moreover, the dimensions of the antenna structure 10 , such as line length, line width, line spacing, and surrounding shape, will vary according to the design of the frequency band. Therefore, the present invention does not limit the relevant design parameters of the antenna structure 10 .

According to the embodiment of the present invention, as mentioned above, when the required transmission frequency of the antenna structure 10 is 434MHz, that is, the shortest antenna length is about 17.27 cm, so it is impossible to install an antenna with such a length in a hand-held electronic device. Therefore, the present invention proposes an antenna structure 10 with a surrounding structure, which can bend the antenna into a surrounding structure as shown in Figure 1, so that the area of the antenna can be greatly reduced to suit various hand-held in the electronic device. Even the transmission line of the antenna structure 10 can be extended to be equal to the length of the wavelength, or a least common multiple of the wavelengths of several frequency bands can be obtained to make an antenna to receive the wavelengths of several frequency bands at the same time. According to the antenna structure 10 of the present invention, a miniaturized antenna can be obtained to save the area and volume of the antenna. In addition to improving the signal transmission and reception effect of the handheld device, the volume of the handheld device can be further reduced.

According to the antenna structure 10 of the embodiment of the present invention, it can have the characteristics of multi-bandwidth operation, and has lower signal strength of higher harmonics such as second harmonic and third harmonic, so as to avoid signal interference of these higher harmonics , and can avoid indirect interference with other electronic devices using wireless transmission and wireless communication, so the antenna structure 10 of the present invention can have excellent communication quality.

FIG. 2 is a graph showing the measurement of the frequency response of the reflection loss according to the first embodiment of the present invention.

FIG. 3 is a graph showing the measurement of the frequency response of the reflection loss according to the second embodiment of the present invention.

FIG. 4 is a graph showing the measurement of the frequency response of the reflection loss according to the third embodiment of the present invention.

FIG. 6 is a graph showing the measurement of the frequency response of the reflection loss according to the fourth embodiment of the present invention.

Please refer to Figure 2. As shown in FIG. 2, the measurement graph of the frequency response of the return loss (Return Loss) according to the first embodiment of the present invention is shown. As shown in the figure, it can be seen that the antenna structure 10 of the present invention can easily obtain the frequency response of the reflection loss. The three frequencies of 436MHz, 1.73GHz, and 3.38GHz can obtain the lowest reflection loss, and these reflection losses are all lower than -20dB. Therefore, it can be seen that the antenna structure 10 of the present invention can operate in three frequency bands of 436MHz, 1.73GHz, and 3.38GHz, and can obtain good antenna radiation efficiency.

Please refer to Figure 3, Figure 4 and Figure 6 at the same time. FIG. 3 , FIG. 4 and FIG. 6 show the measurement graphs of the frequency response of the reflection loss according to the second, third and fourth embodiments of the present invention. FIG. 3 shows the frequency response of the reflection loss obtained by the antenna structure 10 according to the present invention. The lowest reflection loss can be obtained for the three frequencies of 143MHz, 2.53GHz and 2.93GHz. FIG. 4 shows the frequency response of the reflection loss obtained by the antenna structure 10 according to the present invention. The lowest reflection loss can be obtained for the three frequencies of 153 MHz, 2.44 GHz and 2.90 GHz. FIG. 6 shows the frequency response of the reflection loss obtained by the antenna structure 10 according to the present invention. The lowest reflection loss can be obtained for the three frequencies of 141 MHz, 2.40 GHz and 2.83 GHz. Among them, the second embodiment, the third embodiment and the fourth embodiment only slightly modify the parameters of the first embodiment, such as line length, line width, line spacing, number of turns, etc., which can be compared with the other three different The frequency band achieves a reflection loss below -20dB. Therefore, the antenna structure 10 according to the present invention can be applied to the other three frequency bands for transmitting and receiving antenna signals only by slightly modifying parameters. From the first to fourth embodiments of the present invention, it can be seen that the antenna structure 10 of the present invention can obtain ultra-wideband transmission/reception frequency bands, and the reception frequency band can be easily adjusted only by making minor modifications to the design parameters , so the antenna structure 10 of the present invention is an ultra-wideband antenna with an elastically adjustable receiving frequency band.

FIG. 5 is a measurement diagram of a Smith Chart according to a third embodiment of the present invention.

FIG. 7 is a measurement diagram of a Smith Chart according to a fourth embodiment of the present invention.

Please refer to Figure 4 and Figure 7. FIG. 4 is a measurement diagram of a Smith Chart according to a third embodiment of the present invention. Therein, the relative inductive reactance, capacitive reactance and impedance values of the antenna structure 10 according to the present invention at three frequencies of 153 MHz, 2.44 GHz and 2.90 GHz can be obtained. FIG. 7 is a measurement diagram of a Smith Chart according to a fourth embodiment of the present invention. Therein, the relative inductive reactance, capacitive reactance and impedance values of the antenna structure 10 according to the present invention at three frequencies of 141 MHz, 2.40 GHz and 2.83 GHz can be obtained.

FIG. 8 is a measurement diagram of the frequency response of return loss according to the first embodiment of the present invention.

FIG. 9 is a measurement diagram of a Smith Chart according to a first embodiment of the present invention.

Please refer to Figure 8 and Figure 9 at the same time. 8 and 9 are measurement diagrams according to the first embodiment of the present invention, and are scanned in a small bandwidth range (150kHz-867Hz), so only the reflection loss response of the lowest frequency of the first embodiment is seen. From FIG. 8 , it can be seen that the antenna structure 10 according to the first embodiment of the present invention can obtain a reflection loss response of -28.9 dB at 433 MHz, so the antenna structure 10 in the first embodiment can operate in the frequency band of 433 MHz. From FIG. 9 , the values of inductive reactance, capacitive reactance and impedance of the antenna structure 10 of the first embodiment can be known.

FIG. 10 is a diagram illustrating the measurement of electromagnetic wave interference in the vertical direction according to the first embodiment of the present invention.

FIG. 11 is a measurement diagram of electromagnetic wave interference in the horizontal direction according to the first embodiment of the present invention.

Please refer to Figure 10 and Figure 11 at the same time. 10 and 11 are diagrams showing the measurement diagrams of the electromagnetic wave interference in the vertical direction and the horizontal direction according to the first embodiment of the present invention. Among them, it can be seen that there is a black line in FIG. 10 and FIG. 11 , which is the standard limit value of electromagnetic wave interference in safety standards. Except that the measured intensity of the main wave can exceed this specification value, the measured values of other high-order harmonic electromagnetic wave interference must be lower than the specified intensity of this black line. Since the present invention is an antenna structure 10 as shown in FIG. 1 , the signal transmitted by its main wave needs to have relatively high strength, so the signal strength of the main wave can exceed the limit value of safety regulations. In this embodiment, the operating frequency band of the antenna structure 10 shown in FIG. 1 is located at 433 MHz. Therefore, in FIGS. 10 and 11 , it can be measured that the signal strength of the main wave exceeds the safety standard limit at the frequency of 433.92 MHz. And it can be seen that many high-order harmonics are generated on both sides of the 433MHz main wave. The signal strength of these high-order harmonics is all lower than -50dBm, which meets the safety specifications of electromagnetic interference. Therefore, it can be seen that the antenna structure 10 of the present invention can effectively suppress the signal strength of high-order harmonics, thus avoiding the interference of high-order harmonics when sending and receiving signals, and avoiding indirect interference with other wireless transmission and wireless communications. The electronic device can also reduce or avoid the harm to health caused by electromagnetic waves when ordinary users use these electronic devices with the antenna structure 10 shown in FIG. 1 .

FIG. 12 is a diagram illustrating the measurement of high-order harmonic electromagnetic wave interference in the vertical direction according to the first embodiment of the present invention.

FIG. 13 is a diagram illustrating the measurement of high-order harmonic electromagnetic wave interference in the horizontal direction according to the first embodiment of the present invention.

Please refer to Figure 12 and Figure 13 at the same time. FIG. 12 and FIG. 13 are diagrams showing the vertical and horizontal measurement diagrams of the high-order harmonic electromagnetic wave interference according to the first embodiment of the present invention. Among them, it can be seen that in Fig. 12 and Fig. 13, in the frequency band from 1000MHz to 8000MHz, the high-order harmonics of the antenna structure 10 shown in Fig. The invented antenna structure 10 can effectively suppress the signal strength of high-order harmonics, so that it can avoid the interference of high-order harmonics when sending and receiving signals, and can avoid indirect interference with other electronic devices that use wireless transmission and wireless communication. Generally, users can reduce or avoid harm to health caused by electromagnetic waves when using these electronic devices with the antenna structure 10 shown in FIG. 1 .

However, the above description is only a detailed description and drawings of specific embodiments of the present invention, and is not intended to limit the present invention. All scopes of the present invention should be based on the claims, and any ordinary skilled person in the field of the present invention Within, easily conceivable changes or modifications can all be included in the protection scope of the claims defined in this application.

Claims (9)

1. An antenna structure, characterized in that: a continuous transmission line forming a surrounding structure from outside to inside, it has a first end point and a second end point, and the first end point is a free end, and the second end point is electrically connected to a ground end; and A signal feed-in point is electrically connected to the continuous transmission line and is two-thirds of the wavelength away from the second end point. 2. The antenna structure according to claim 1, wherein the signal feeding point is for feeding the antenna signal into the antenna structure. 3. The antenna structure as claimed in claim 1, further comprising a substrate on which the antenna structure is formed. 4. The antenna structure according to claim 3, wherein the substrate is an FR4 substrate. 5. The antenna structure according to claim 1, wherein the surrounding structure is a circle, a square, a triangle, an ellipse or a ring formed by two semicircles and a long straight transmission line. 6. The antenna structure as claimed in claim 1, wherein the surrounding structure forms an inductor. 7. The antenna structure as claimed in claim 1, wherein the surrounding structure has multiple turns. 8. The antenna structure as claimed in claim 1, wherein the transmission line has a line width of 0.2 mm. 9. The antenna structure as claimed in claim 1, wherein the transmission line has a pitch of 0.2 mm.

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