WO2016061997A1

WO2016061997A1 - Antenna structure

Info

Publication number: WO2016061997A1
Application number: PCT/CN2015/074777
Authority: WO
Inventors: 谢一泓
Original assignee: 中兴通讯股份有限公司
Priority date: 2014-10-21
Filing date: 2015-03-20
Publication date: 2016-04-28
Also published as: CN204243174U

Abstract

An antenna structure comprises a dual-arm antenna and a mainboard. The mainboard is connected to the dual-arm antenna and is used for feeding power to the dual-arm antenna. The dual-arm antenna comprises a first arm used for low-frequency resonance, a second arm used for high-frequency resonance, and a coupling branch. A first end of the first arm and a first end of the second arm are respectively connected to the mainboard. The coupling branch is parallel to the second arm and comprises a first branch portion and a second branch portion. The first branch portion and a first portion of the second arm are arranged side by side. The first portion of the second arm forms one part of a second end of the second arm extending towards the first end. The second branch portion extends away from the first end of the second arm relative to the first branch portion. The second branch portion is connected to the first arm. By means of the antenna structure, the specific absorption rate (SAR) of the antenna and the radiation injury to the human body are reduced.

Description

Antenna structure

Technical field

This paper relates to the field of communications, and in particular to an antenna structure.

Background technique

SAR is the specific absorption rate. Under the action of an external electromagnetic field, an induced electromagnetic field will be generated in the human body. Since every organ in the human body is a lossy medium, the electromagnetic field in the body will generate electric current, resulting in absorption and dissipation of electromagnetic energy. SAR is commonly used in biodoping to characterize this physical process. SAR is defined as the electromagnetic power absorbed or consumed by human tissue per unit mass in W/kg.

With the rapid development of wireless communication technology, wireless terminals (mobile phones, data cards, MiFi/Hotspot) products have been widely used in life. At the same time, the public is increasingly concerned about the impact of electromagnetic radiation from wireless terminal products on human health. Therefore, many markets currently require SAR for mobile terminal products, and many products must meet FCC/CE SAR requirements. This puts higher requirements on the design of the mobile terminal antenna. The current SAR technology reduces the cable power and absorbing materials. These aspects are either sacrificing the total radiated power TRP of the antenna, affecting the communication signal, or increasing the cost and process complexity. The antenna design really solves the problem of SAR.

Related small-sized, thin and light mobile terminals leave the antenna with a small headroom and a low height. In the case of more frequency bands to be covered, the antenna design can basically be unipolar multi-arm, monopole plus parasitic IFA plus parasitic and other forms, and the high frequency (1700-2700MHz) that comes out of these kinds of routing forms, although the performance of the active test OTA is generally good, the SAR value is generally high, and even the SAR value exceeds the standard, becoming a mobile terminal. One of the challenges in antenna design.

As shown in FIG. 1 , it is a common single-pole dual-arm antenna. In the antenna structure, the main board 1 is connected to the single-pole dual-arm antenna through a feeding point and an impedance matching network to feed the single-pole dual-arm antenna.

2 is a detailed structural diagram of the conventional single-pole dual-arm antenna of FIG. 1. The common single-pole dual-arm antenna is composed of two arms, that is, a low-frequency long arm 51 and a high-frequency short arm 52; wherein the low-frequency long arm 51 is mainly configured to achieve low-frequency resonance. In an ideal situation, it is also possible to adjust its length and impedance matching network, using its double frequency The resonance of the current high frequency band, but the high frequency bandwidth is narrow at this time, and the resonance position is limited; the high frequency short arm 52 is set to achieve high frequency resonance, and the design is flexible, and the length can be freely controlled according to the required frequency band. Ideally, the length of the two arms and the impedance matching network can be adjusted so that the double resonance of the low frequency long arm 51 and the resonance generated by the high frequency short arm 52 are interleaved to widen the bandwidth of the antenna. However, the main disadvantage of such a conventional single pole dual arm antenna is that the SAR value of the high frequency band realized by the high frequency short arm 52 is generally high.

Summary of the invention

Embodiments of the present invention provide an antenna structure to solve the technical problem of how to effectively reduce the specific absorption rate SAR of a dual-arm antenna.

In order to solve the above technical problem, an embodiment of the present invention provides an antenna structure, including:

Double arm antenna

a main board connected to the dual-arm antenna and feeding the dual-arm antenna;

The dual-arm antenna includes: a first arm configured to achieve low-frequency resonance, a second arm configured to achieve high-frequency resonance, and a coupling branch;

The first end of the first arm and the first end of the second arm are respectively connected to the main board;

The coupling branch is parallel to the second arm, and the coupling branch includes: a first branch portion and a second branch portion, wherein the first branch portion is disposed side by side with the first portion of the second arm, the first a first portion of the second arm is formed as a portion of the second end of the second arm extending toward the first end; the second branch portion is away from the first end of the second arm relative to the first branch portion The direction of the extension is; the second branch portion is connected to the first arm.

Optionally, the length of the first branch portion is less than 10 mm.

Optionally, a distance of an end of the second branch portion away from the first branch portion and a second end of the first arm is between 10 mm and 15 mm.

Optionally, the first end of the first arm is connected to the main board through a feeding point and impedance matching.

Optionally, the first end of the second arm is coupled to the first end of the first arm.

Optionally, the first end of the second arm is connected to the main board through a grounding point.

Optionally, the distance between the grounding point and the feeding point is less than a preset value, and the preset value is 5 mm.

Optionally, when the dual-arm antenna is an inverted-F dual-arm antenna, the first end of the first arm is further connected to the main board through the grounding point.

Optionally, the first end of the second arm is connected to the main board through the grounding point.

The beneficial effects of the above technical solutions are as follows:

In the above solution, the antenna structure includes a main board and a dual-arm antenna, and the main board feeds the two-arm antenna through a feeding point and impedance matching; the first arm of the dual-arm antenna is connected to the main board through impedance matching and a feeding point, The two arms are led out from the beginning of the first arm or are led out by the grounding point; in addition, the coupling branch is also led out from the end of the first arm, and the coupling branch is coupled with the second arm end in parallel, and the second current is changed by coupling. The distribution and dispersion of the electric field improve the high-band SAR value achieved by the second arm in the ordinary single-pole dual-arm antenna, and reduce the SAR value of the antenna.

BRIEF abstract

1 is a schematic structural view of a related conventional single-pole dual-arm antenna;

Figure 2 is a detailed structural view of the conventional single-pole dual-arm antenna of Figure 1;

3 is a schematic structural view of an antenna according to an embodiment of the present invention;

4 is a detailed structural diagram of an antenna of the embodiment of the present invention in FIG. 3;

FIG. 5 is a detailed structural diagram of still another antenna in the embodiment of the present invention; FIG.

6 is a detailed structural diagram of an IFA dual-arm antenna in an embodiment of the present invention;

Fig. 7 is a view showing the detailed structure of still another IFA dual-arm antenna in the embodiment of the present invention.

Description of the reference signs:

1-motherboard; 2-feed point; 3-impedance matching; 4-ground point; 5-arm antenna; 51-low frequency long arm; 52-high frequency short arm; 521-first part of high frequency short arm; - coupling branch section; 531 - first branch section; 532 - second branch section.

Preferred embodiment of the invention

The embodiments will be described in detail below with reference to the accompanying drawings.

The embodiment of the present invention provides an antenna structure for the problem that the current terminal SAR value is relatively high.

As shown in FIG. 3 to FIG. 7 , an embodiment of the present invention provides an antenna structure, which can reduce a high frequency SAR value of a terminal, where the antenna includes:

Double arm antenna 5;

a main board 1 connected to the dual-arm antenna 5 and feeding the dual-arm antenna 5;

Optionally, the dual-arm antenna 5 includes: a first arm configured to achieve low-frequency resonance, a second arm configured to achieve high-frequency resonance, and a coupling branch 53, a first arm configured to achieve low-frequency resonance in this embodiment Corresponding to the low frequency long arm 51 shown in FIG. 4, the second arm provided to realize high frequency resonance corresponds to the high frequency short arm 52 shown in FIG.

The first end of the low frequency long arm 51 and the first end of the high frequency short arm 52 are respectively connected to the main board;

The coupling branch 53 is parallel to the high frequency short arm 52 and includes: a first branch portion 531 and a second branch portion 532, wherein the first branch portion 531 and the first portion 521 of the high frequency short arm Positioned side by side, the first portion 521 of the high frequency short arm forms a portion of the second end of the high frequency short arm 52 extending toward the first end; the second branch portion 532 is opposite to the first branch portion 531 Extending from a direction away from the first end of the high frequency short arm 52; the second branch portion 532 is coupled to the low frequency long arm 51.

Optionally, the length of the first branch portion 531 is less than 10 mm; the distance between the end of the second branch portion 532 away from the first branch portion 531 and the second end of the low frequency long arm 51 is located at 10 mm to Between 15mm.

The first end of the low frequency long arm 51 is connected to the main board 1 through a feeding point 2 and an impedance matching 3, and the first end of the high frequency short arm 52 is opposite to the first end of the low frequency long arm 51. connection. Optionally, the first end of the high frequency short arm 52 can also be directly connected to the main board 1 through the grounding point 4.

Optionally, the distance between the grounding point 4 and the feeding point 2 is less than a preset value, and the preset value is 5 mm.

Optionally, when the dual-arm antenna is an inverted-F dual-arm antenna, the first end of the low-frequency long arm 51 is further connected to the main board 1 through the grounding point 4, the high-frequency short arm A first end of the 52 is coupled to the first end of the low frequency long arm 51. Optionally, the first end of the high frequency short arm 52 can also be connected to the main board 1 through a grounding point 4.

In the above solution, the main board feeds the two-arm antenna through the feeding point and the impedance matching; The line consists of a low-frequency long arm, a high-frequency short arm and a coupling branch; the low-frequency long arm is connected to the main board through impedance matching and a feeding point; the high-frequency long arm is led out from the beginning of the low-frequency short arm or is led out by the grounding point; The distance between the grounding points is generally less than 5 mm; the coupling branches are drawn from the end of the low-frequency long arm 10-15 mm, and the ends of the high-frequency short arms are staggered in parallel, and the staggering distance is less than 10 mm. The coupling branch is coupled with the end of the high-frequency short arm in parallel, and the current distribution on the high-frequency short arm is changed by coupling to disperse the electric field, thereby improving the high-band SAR value of the ordinary single-pole dual-arm antenna realized by the high-frequency short arm. In the higher case, the SAR value of the antenna is lowered.

As shown in FIG. 3, the antenna in the embodiment of the present invention also includes a main body including a main board 1, a feeding point 2, a grounding point 3, an impedance matching 4, and a monopole dual-arm antenna 5.

As shown in FIG. 4, unlike the conventional single-pole dual-arm antenna, the single-pole dual-arm antenna of the present embodiment includes a coupling branch 53 in addition to the low-frequency long arm 51 and the high-frequency short arm 52. The working principle of the dual-arm antenna is similar to that of the ordinary monopole antenna. The low-band resonance is realized by the local oscillator resonance of the low-frequency long arm 51, and the high-band resonance is performed by the double frequency of the low-frequency long arm 51 and the high-frequency short arm 52. achieve. Since the SAR value of the high frequency band realized by the high frequency short arm 52 in the ordinary single pole dual arm antenna is relatively high, the coupling branch 53 is introduced into the antenna design in this embodiment, that is, it is taken out from the end of the low frequency long arm 51 by 10-15 mm. A short trace runs in the direction of the high frequency short arm 52 and is parallel to the end of the high frequency short arm 52 and has a side-by-side arrangement with a staggered distance of less than 10 mm. Since the coupling branch 53 drawn from the low-frequency long arm 51 is short, the influence on the low-frequency resonance is small, and the low-frequency resonance performance remains substantially unchanged; and the coupling branch 53 and the high-frequency short arm 52 are equally staggered, and the original height is changed by the coupling action. The current distribution on the short arm 52 changes the surrounding electromagnetic field and disperses it, thereby achieving the purpose of reducing the high frequency SAR value.

As shown in FIG. 5, another implementation form of reducing the SAR monopole dual-arm antenna in this embodiment is shown. In this implementation, the high-frequency short arm 52 is directly connected to the grounding point 4 as a parasitic branch, instead of being drawn from the beginning of the low-frequency long arm 51, which is fed by the coupling with the low-frequency long arm 51, which can be realized. High frequency band resonance. By the coupling action of the high frequency short arm 52 and the coupling branch 53, the SAR value of the high frequency resonance generated by the high frequency short arm 52 can also be lowered.

As shown in FIG. 6, in this embodiment, another implementation form of reducing the SAR dual-arm antenna is realized by the form of an IFA antenna + a parasitic branch. The main board 1 is connected to the low frequency long arm 51 of the dual arm antenna 5 through the feeding point 2 and the impedance matching 3, and the low frequency long arm 51 also passes through the grounding point 4 Connected to the main board 1 to achieve low-frequency resonance with an IFA antenna and high-frequency partial resonance with its double frequency. The high-frequency short arm 52 is led out from the beginning of the low-frequency long arm 51 to realize high-frequency resonance; by adjusting its length and impedance matching, the resonance generated by it is interleaved with the resonance generated by the double-frequency of the low-frequency long arm 51, and the high-frequency bandwidth can be broadened. . The coupling branch 53 is taken out from the end of the low-frequency long arm 51 by 10-15 mm, is routed along the direction of the high-frequency short arm, and is parallel with the end of the high-frequency short arm and has a side-by-side arrangement, and the staggered distance is less than 10 mm. The coupling of the high-frequency short arm changes the current on the high-frequency short arm to disperse the nearby electromagnetic field distribution and reduce the high-frequency SAR value.

As shown in FIG. 7, another implementation form of reducing the SAR dual-arm antenna in this embodiment. The low frequency long arm 51 of the dual arm antenna is implemented by the IFA antenna like the antenna of FIG. The difference is that the high frequency short arm 52 is led out by the grounding point 4 instead of the beginning of the low frequency long arm 51. The high frequency short arm 52 in this implementation is fed by its coupling with the low frequency long arm 51 to achieve high frequency resonance. Similarly, the high frequency SAR value is reduced by the coupling between the high frequency short arm 52 and the coupling branch 53.

Table 1

Table 2

For this embodiment, the performance of a conventional single pole dual arm antenna as in Fig. 1 and a single pole dual arm antenna (see Fig. 3) which can effectively reduce the SAR value of the mobile terminal in this embodiment is compared. See Table 1 and Table 2. Table 1 shows the performance of the ordinary single-pole dual-arm antenna, and Table 2 shows the performance table of the SAR single-pole dual-arm antenna. Among them, WCDMA850, WCDMA1700 and WCDMA1900 represent three frequency bands, and SAR represents the SAR value of the antenna corresponding to a certain channel of a certain frequency band. The SAR data in the table is tested under the Speag Dasy5SAR test system.

It can be seen from Table 1 and Table 2 that compared with the ordinary single-pole dual-arm antenna, the WCDMA1700 with the parasitic high-frequency short arm is reduced in the total radiated power (TRP). With the same constant, the SAR of the three channels (8762, 8846, 8912) has decreased. The smallest SAR is the intermediate channel 8846. The TRP is basically the same (normal single-pole dual-arm antenna 19.4, SAR unipolar) The two-arm antenna 19.7), the maximum surface SAR values are: ordinary single-pole dual-arm antenna 1.86, SAR single-pole dual-arm antenna 1.07. It can be seen that in the case of equivalent TRP, the SAR value of the low-frequency and high-frequency bands realized by the low-frequency long arm is basically the same, and the high-frequency SAR realized by the parasitic high-frequency short arm is adopted. Can be reduced by about 0.8W/Kg.

In this way, the present embodiment extracts the coupling branch on the low-frequency long arm of the dual-arm antenna and traces it along the direction of the high-frequency short arm so as to be parallelized with the end of the high-frequency short arm to generate a coupling effect, thereby changing the high-frequency short arm. The current distribution on the distributed electromagnetic field distribution reduces the high frequency SAR value.

In addition, the relative position between the dual-arm antenna and the main board can be arbitrary, depending on the product designed The reserved antenna clearance depends on. For products with a certain thickness, the height of the antenna design space is guaranteed, and it can be realized by a bracket antenna or an LDS antenna (formed directly by laser). At this time, the dual-arm antenna can be located in the upper area or the lower area of the main board; for ultra-thin products, the antenna The design space is highly limited, and the single-pole dual-arm antenna can be directly etched on the main board, using a PCB antenna (the part of the printed circuit board for wireless reception and transmission).

The antenna structure of the above embodiment of the invention extracts the coupling branch from the low-frequency long arm of the dual-arm antenna. Since the coupling branch is led out from the end of the low-frequency long arm and has a short length, it has little effect on the low-frequency performance of the antenna; the coupling branch and the high The ends of the short-frequency arm are parallel-staggered for coupling, and the current distribution on the high-frequency short arm is changed by coupling to disperse the electric field, thereby improving the high-band SAR value achieved by the high-frequency short arm in the ordinary single-pole dual-arm antenna. Reduce the SAR value of the antenna and reduce the damage to the human body.

The above is a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Industrial applicability

The above technical solution improves the high-band SAR value achieved by the second arm in the ordinary single-pole dual-arm antenna, and reduces the SAR value of the antenna.

Claims

An antenna structure comprising:

Double arm antenna

a motherboard that is coupled to the dual-arm antenna and feeds the dual-arm antenna,

The dual-arm antenna includes: a first arm configured to achieve low-frequency resonance, a second arm configured to achieve high-frequency resonance, and a coupling branch;

The first end of the first arm and the first end of the second arm are respectively connected to the main board;

The coupling branch is parallel to the second arm, and the coupling branch includes: a first branch portion and a second branch portion, wherein the first branch portion is disposed side by side with the first portion of the second arm, the first a first portion of the second arm is formed as a portion of the second end of the second arm extending toward the first end; the second branch portion is away from the first end of the second arm relative to the first branch portion The direction of the extension is; the second branch portion is connected to the first arm.
The antenna structure of claim 1 wherein said first branch portion has a length of less than 10 mm.
The antenna structure according to claim 1, wherein a distance of an end of the second branch portion away from the first branch portion from a second end of the first arm is between 10 mm and 15 mm.
The antenna structure of claim 1 wherein the first end of the first arm is coupled to the motherboard by a feed point and impedance matching.
The antenna structure of claim 4 wherein the first end of the second arm is coupled to the first end of the first arm.
The antenna structure of claim 4 wherein the first end of the second arm is coupled to the motherboard by a ground point.
The antenna structure according to claim 6, wherein a distance between the grounding point and the feeding point is less than a predetermined value, and the preset value is 5 mm.
The antenna structure according to claim 4, wherein when the dual-arm antenna is an inverted-F dual-arm antenna, the first end of the first arm is further connected to the main board through the grounding point.
The antenna structure of claim 8 wherein the first end of the second arm is coupled to the first end of the first arm.
The antenna structure of claim 8 wherein the first end of the second arm is coupled to the motherboard via the ground.