WO2009015579A1

WO2009015579A1 - Multiband antenna and method for achieving multiband antenna

Info

Publication number: WO2009015579A1
Application number: PCT/CN2008/071695
Authority: WO
Inventors: Hai Wang
Original assignee: Shenzhen Huawei Telecommunication Technologies Co., Ltd.
Priority date: 2007-07-27
Filing date: 2008-07-18
Publication date: 2009-02-05
Also published as: CN101123325A

Abstract

A multiband antenna and a method for achieving multiband antenna are used in mobile communication field. The multiband antenna includes an antenna body, at least a switch is set on the antenna body, the switch is used to control the antenna to support different frequency in different state. The method for achieving multiband antenna includes the steps of that: at least a switch is set on the antenna body of the multiband antenna, control signal is set to control the state of the switch on the antenna body, so as to make the multiband antenna support different frequency. Using the multiband antenna in the invention, supporting multiple band is achieved by changing the state of the switch on the antenna body, compared with that the resonance branch is required to increased when supporting multiband in prior art, the area of the antenna is greatly saved and the occupied space of the antenna is decreased, so efficiency of the antenna is improved.

Description

Multi-band antenna and method for realizing multi-band antenna

The present invention relates to the field of mobile communications, and in particular, to a multi-band antenna and a method for implementing a multi-band antenna. Background technique

In mobile systems, such as GSM (Globa Systems for Mob i lecommunication) systems, from the early stage only need to support the frequency of 90 OMH z, to the need to support two frequencies of 900 / 1800MHZ In the current 3G era, it is even necessary to support multiple frequency bands such as 850/900/1800/1900/ 2100MHZ, and higher and higher requirements are imposed on hardware devices, especially terminal antennas.

The role of the antenna is to effectively transmit and effectively receive the RF signal, and the resonant branch of the antenna has a frequency bandwidth. In order to achieve the broadband frequency characteristics required in the mobile system, the same mobile terminal must support The frequencies required in GSM900 must support the frequencies required in GSM1800. Either use multiple antennas or, in the case of one tap, use multiple resonant branches.

In existing mobile terminal systems, multiple resonant branches are typically used to achieve antenna widening. Take the mobile terminal antenna supporting 900/1800MHZ in the GSM system as an example. Referring to FIG. 1 , in order to support an antenna structure diagram of a 900/1800 MHz mobile terminal, the antenna system is composed of a circuit board, an antenna feed point, and an antenna body, and a signal is introduced from the antenna feed point to the antenna body, and the antenna body is branched by branch 1 and branch 1. composition. Among them, branch 1 has a long trace, low resonance frequency, realizes 900MHz signal radiation, branch 1 has a short trace, and has a high resonance frequency to achieve signal radiation of 1800MHz; therefore, the antenna can simultaneously support two frequency bands of 900/1800MHz. The antenna body can be a trace printed on a circuit board or a metal conductor placed on a structure outside the board. See Fig. 2, which is the frequency-reflection return loss graph of the antenna. It can be seen from the curve in the figure that the reflection return loss of the antenna at 900MHz and 1800MHz is about -20dB.

In the process of implementing the present invention, the inventors found that at least the following problems exist in the prior art. question:

The space occupied by the antenna is too large, which does not meet the trend and requirements of miniaturization of the terminal. Since the natural resonant bandwidth of each branch is limited, when it is necessary to support more transmission signals,

-kv 900/1800/2100MHz, even when supporting other services such as GPS (Globa Postation System), only more branches can be used to support multiple bands, but it takes up more space.

Summary of the invention

In order to enable the antenna of the mobile terminal to support multiple frequency bands, the embodiment of the present invention provides a multi-band antenna and a method for implementing the multi-band antenna.

At least one switch is disposed on the antenna body, and the switch is configured to control the multi-band antenna to support different frequencies in different states.

The multi-band antenna provided by the embodiment of the present invention uses the antenna body provided with the switch, and when the switch is set to a different state (that is, the length of the effective metal conductor antenna body is different by using different states of conduction or isolation of the switch) Supporting different frequency bands; Compared with the prior art to support multi-band, it is necessary to increase the area of the antenna and reduce the space occupied by the antenna. In addition, since there is only one transmission path of the signal in the multi-band antenna , the coupling phenomenon caused by multiple transmission paths will not occur, so the efficiency of the antenna can be improved.

The method for implementing a multi-band antenna includes:

At least one switch is disposed on the antenna body of the multi-band antenna, and a control signal is set to control a state of the switch on the antenna body to enable the multi-band antenna to support different frequencies.

Compared with the prior art, the embodiment of the invention has the following advantages:

The method for implementing a multi-band antenna provided by the embodiment of the present invention can support multiple frequency bands by supporting multiple frequency bands by controlling the state of the switch on the antenna body of the multi-band antenna. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are used in the description of the claims Other drawings can also be obtained from these drawings on the premise of creative labor.

1 is an antenna configuration diagram of a mobile terminal supporting 900 MHz and 1800 MHz in the prior art;

2 is a frequency-reflection return loss graph of the antenna of FIG. 1;

3 is a structural diagram of a multi-band antenna according to an embodiment of the present invention;

4 is a circuit diagram of a multi-band antenna according to an embodiment of the present invention;

Figure 5 is a structural diagram of a switch module of the multi-band antenna of Figure 4;

6 is a flowchart of a method for implementing a multi-band antenna according to an embodiment of the present invention; FIG. 7 is a physical output effect diagram when the multi-band antenna of FIG. 4 supports a lowest frequency; FIG. 8 is a multi-band antenna support of FIG. Frequency-reflection return loss graph at the lowest frequency;

9 is a physical output effect diagram of the multi-band antenna of FIG. 4 supporting a higher frequency; FIG. 10 is a frequency-reflection return loss curve diagram of the multi-band antenna of FIG. 4 supporting a higher frequency;

Fig. 1 1 is a physical output effect diagram when the multi-band antenna of Fig. 4 supports the highest frequency; Fig. 12 is a frequency-reflection return loss curve diagram of the multi-band antenna of Fig. 4 supporting the highest frequency. detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

In order to make the objects, technical solutions and advantages of the present invention more clear, the following will be combined with the accompanying drawings. The embodiments of the present invention are further described in detail.

Referring to FIG. 3, an embodiment of the present invention provides a multi-band antenna, including a circuit board, an antenna feed point, and an antenna body. The signal is introduced from the antenna feed point to the antenna body, and the circuit board is placed horizontally at the bottom of the multi-band antenna. a ground plane, an antenna body is drawn on the antenna feed point of the circuit board, the antenna body is above the circuit board, and the antenna feed point is in contact with the circuit board, and at least one switch is disposed on the antenna body, and the switch is used to control different The multi-band antenna supports different frequencies. The antenna body may be a trace printed on the circuit board or a metal conductor placed on the structure outside the circuit board. The shape of the metal conductor can be differently shaped as needed, such as a straight line, a return line, a fold line, a zigzag line, or the like, or a combination of different shapes.

The above switch may be an active switch or a mechanical switch, and the structure may be a simple switch structure or a switch module including a capacitor. Referring to FIG. 4, two switch modules, a switch module 1 and a switch module 2 are disposed on the antenna body, thereby dividing the antenna body into three segments, a branch 1-1, a branch 1-2, and a branch 1 _3. The structure of the switch module is shown in FIG. 5. In the switch module, the main body is a switching device, and the two sides of the switch device respectively have capacitors. Through the control of the control signal, the transmission signal can pass or not pass through the switching device, and the function of turning on or blocking is realized. The control signal is derived from the baseband. According to the actual network frequency, the state of the switch is set to select the corresponding frequency. The function of the capacitors on both sides of the switching device is to make the switch work normally and ensure the DC path required by the switch. For the antenna body, when a plurality of switches are disposed thereon, a capacitor can be disposed between the adjacent two switches, thereby functioning as an isolation.

When a switch is disposed on the antenna body, the multi-band antenna can support two frequency bands. When two switches are disposed on the antenna body, the multi-band antenna can support three frequency bands, and so on, the switch disposed on the antenna body. The more the multi-band antennas can support the more frequency bands. The switch disposed on the antenna body can be specifically configured to control the multi-band antenna to support the lowest frequency in the fully closed state, and control the multi-band antenna to support the highest frequency when the switch closest to the feed point is open, and control All switches enable a multi-band antenna to support frequencies other than the lowest frequency and highest frequency in the combined state of open and closed. When the multi-band antenna is required to support the lowest frequency, all the switches on the antenna body can be controlled to be set to a closed (on) state; wherein, the lowest frequency refers to the lowest frequency among the frequencies that the multi-band antenna can support, for example, multi-band The antenna can support GSM900MHz, DCS (Data Communication [Conditioning] System, data transmission system) 1800MHz, PCS (Personal Communication Systems) 1900MHz and WLAN (Wireless Local Area Network) 2500MHz four frequency bands, The lowest frequency is GSM900MHz, and three switches can be set on the antenna body. When the three switches are fully closed, the multi-band antenna can support the lowest frequency of 900MHz.

When the multi-band antenna is required to support the highest frequency, the switch closest to the antenna feed point on the antenna body can be controlled to be set to an open state; wherein, the highest frequency refers to the highest frequency among the frequencies that the multi-band antenna can support, for example, a multi-band antenna It can support three frequency bands of GSM900MHz, GPS1500MHz and WCDMA2100MHz. The highest frequency is WCDMA2100MHz. Two switches can be set on the antenna body of multi-band antenna. It is assumed that switch 1 and switch 2 will be switched from near to far from the antenna feeder. When the 1 is turned on, the multi-band antenna can support the highest frequency of 2100MHz. At this time, the state of the other switches may be open or closed, and the length of the antenna body is not affected; for example, referring to FIG. 4, the switch on the antenna body closest to the antenna feed point, that is, the switch in the switch module 1, can be opened. The band antenna supports the highest frequency. At this time, the switch in the switch module 2 can be opened or closed, that is, after the switch in the switch module 1 is opened, the length of the antenna body is fixed.

When the frequency supported by the multi-band antenna needs to be changed from low to high, it can be controlled to start from the switch on the antenna body farthest from the antenna feed point, and the switches on the antenna body are sequentially set to the open state (ie, all switches are assumed to be initial) For example, the multi-band antenna can support four frequency bands of GSM900MHz, DCS1800MHz, PCS1900MHz and WCDMA2100MHz. Three switches are arranged on the antenna body of the multi-band antenna, assuming that the switch 1 is switched from the antenna feed point to the near end. , switch 2 and switch 3, and all switches in the initial state are closed, that is, the minimum frequency of 900MHz is initially supported, then switch 3, switch 2 and switch 1 are turned on in turn, so that the multi-band antenna can support DCS1800MHz, The frequencies of PCS1900MHz and WCDMA2100MHz, ie the supported frequencies vary from low to high. In addition, when the frequency supported by the multi-band antenna needs to be changed from high to low, it is also possible to control the switch from the antenna body closest to the antenna feed point, and then set the switch to the closed state in turn (ie, all switches are not initialized when H is not initialized) Open state).

In order to enable the multi-band antenna to support more frequency bands, the length of the antenna body may be set to a length corresponding to the multi-band antenna capable of supporting the lowest frequency. According to the relationship between the length of the antenna body and the frequency supported by the antenna in the prior art, the length of the corresponding antenna body when the antenna body supports the lowest frequency can be calculated, and the antenna body in the multi-band antenna is set to the length, This multi-band antenna is enabled to support the widest range of frequency bands. The shorter the antenna body is, the higher the frequency supported by the corresponding antenna is. Therefore, by setting a plurality of switches at different positions of the antenna body, the length of the antenna body can be changed by changing the state of the switch, so that the multi-band antenna supports different frequency.

The multi-band antenna in the embodiment of the present invention supports different frequency bands when the switch is set to different states (that is, the lengths of the effective antenna body are different) by using the antenna body provided with the switch; when the switch is opened, the length of the antenna body is changed. Short, multi-band antennas can support high frequencies. When the switch is closed, the length of the antenna body becomes longer. Multi-band antennas can support low frequencies. Compared with the prior art, when multiple bands are supported, the antenna branches can be greatly saved. Area, reduce the space occupied by the antenna. In addition, since there is only one transmission path of the signal in the multi-band antenna, there is no coupling phenomenon due to multiple transmission paths, so the efficiency of the antenna can be improved. By using capacitors for isolation, the high isolation of the switch is effectively utilized, and isolation of more than 20 dB can be achieved, ensuring that the split branch does not participate in the transmission channel of the useful signal, thereby improving the efficiency of the antenna. By setting the antenna body to a multi-band antenna to support the corresponding length at the lowest frequency, multi-band antennas can support more frequency bands.

Referring to FIG. 6, the embodiment of the present invention further provides a method for implementing a multi-band antenna, which specifically includes the following steps:

Step 101: Set at least one switch on the antenna body of the multi-band antenna; Step 102: Set a control signal to control the state of the switch on the antenna body so that the multi-band antenna supports different frequencies.

Wherein, setting a control signal to control the state of the switch on the antenna body to make multi-band days The steps of the line to support different frequencies can be specifically as follows:

Set the low frequency control signal to control all the switches on the antenna body to be closed, so that the multi-band antenna supports the lowest frequency. The lowest frequency refers to the lowest frequency among the frequencies that the multi-band antenna can support. For example, the multi-band antenna can support four bands of GSM900MHz, DCS1800MHZ, PCS1900MHz and WLAN2500MHz, and the lowest frequency is GSM900MHZ. Three switches can be set on the antenna body. When the three switches are fully closed, the multi-band antenna can support the lowest frequency of 900 MHz;

The step of setting a control signal to control the state of the switch on the antenna body so that the multi-band antenna supports different frequencies may also be specifically:

Set the high frequency control signal to control the switch on the antenna body closest to the antenna feed point to be on, so that the multi-band antenna supports the highest frequency. The highest frequency refers to the highest frequency that the multi-band antenna can support. For example, the multi-band antenna can support three frequency bands: GSM900MHz, GPS1500MHz and WCDMA2100MHz. The highest frequency is WCDMA2100MHZ, which can be set on the antenna body of the multi-band antenna. The switches, assuming that switch 1 and switch 2 are in turn from the antenna feed point, the multi-band antenna can support the highest frequency 2100 MHz when the switch 1 is turned on; at this time, the state of the other switches can be open or closed. , the length of the antenna body is not affected; for example, referring to FIG. 4, the switch in the switch module 1 that is closest to the antenna feed point on the antenna body is turned on, so that the multi-band antenna supports the highest frequency. At this time, the switch module The switch in 2 can be opened or closed, that is, after the switch in the switch module 1 is opened, the length of the antenna body is fixed;

The step of setting a control signal to control the state of the switch on the antenna body to enable the multi-band antenna to support different frequencies may be specifically as follows:

The intermediate frequency control signal is set to control all the switches on the antenna body to be in a combined state of opening and closing, so that the multi-band antenna supports other frequencies than the lowest frequency and the highest frequency. For example, when the frequency supported by the multi-band antenna is required to change from low to high, starting from the switch on the antenna body that is farthest from the antenna feed point, the switches on the antenna body are sequentially turned on (ie, all switches are initially closed); In addition, when the frequency supported by the multi-band antenna needs to be changed from high to low, it can also start from the switch on the antenna body that is closest to the feeder. Close the switch in turn (assuming all switches are on at the beginning).

For example, the multi-band antenna can support four frequency bands of GSM900MHz, DCS1800MHz, PCS1900MHz and WCDMA2100MHz. Three switches are arranged on the antenna body of the multi-band antenna, and it is assumed that the switches 1, switch 2 and switch 3 are sequentially from the start to the far end. In the initial state, all the switches are in a closed state, that is, the minimum frequency of 900MHz is initially supported, and then the switch 3, the switch 2 and the switch 1 are turned on in turn, so that the multi-band antenna can support the frequencies of DCS1800MHz, PCS1900MHz and WCDMA2100MHz, respectively. The supported frequencies vary from low to high.

Further, when a plurality of switches are disposed on the antenna body of the multi-band antenna, a capacitor may be disposed between the adjacent two switches to function as an isolation.

The multi-band antenna with two switches in FIG. 4 is taken as an example. It is assumed that the antenna body is a metal conductor, the switch in the switch module 1 is simply referred to as switch 1, and the switch in the switch module 2 is simply referred to as switch 2. The specific instructions are as follows:

When the minimum frequency needs to be transmitted, the low frequency control signal is set, and both switch 1 and switch 2 are closed. At this time, the metal conductor of the multi-band antenna is the longest branch, and the physical output effect is as shown in FIG. 7; that is, branch 1-1 The branch 1-2 and the branch 1_3 all participate in the signal radiation at the same time. The output performance of the multi-band antenna is shown in Fig. 8. It can be seen from the frequency-feedback return loss graph in Fig. 8 that the reflection is in the range of 880MHz_935MHz. The coefficients are all less than -16dB, and the corresponding standing wave is less than 1.4.

When a higher frequency needs to be transmitted, the intermediate frequency control signal is set, the switch 1 is closed, the switch 2 is opened, and the branches 1-1 and 1-2 are involved in signal radiation, and the branches 1-3 are only used as a metal body. The physical output effect is shown in Figure 9. See Figure 10 for the frequency-feedback return loss graph of the multi-band antenna. It can be seen from the figure that the reflection coefficient is less than -lldB in the range of 1700MHz~2080MHz. The corresponding standing wave is less than 1.8; the standing wave is less than 2 at the frequency of 2.2 GHz, which can fully meet the standing wave requirements of the existing terminal antenna.

When a higher frequency needs to be transmitted, a high frequency control signal is set, and both switch 1 and switch 2 are turned on, that is, only branch 1-1 participates in signal radiation, and branch 1-2 and branch 1_3 are only used as a metal body, physical output. The effect is shown in Figure 11; see Figure 12 for this The frequency-feedback return loss graph of the multi-band antenna, as can be seen from the figure,

In the range of 2300MHz~2450MHz, the reflection coefficient is less than -12dB, and the corresponding standing wave is less than 1.7.

Therefore, it can be seen from the output of the above segments that the multi-band antenna has a standing wave of less than 2 in the bands of GSM900MHz, DCS1800 MHz, PCS1900 MHz, WCDAM2100 MHz and WLAN 2500 MHz~2690MHz, which satisfies the requirements of the terminal antenna.

The technical solution for implementing the multi-band antenna in the embodiment of the present invention can control the state of the switch on the antenna body of the multi-band antenna by setting a control signal, so that the multi-band antenna can support multiple frequency bands; the switch is in different states, and the antenna is changed. The length of the body, so that the multi-band antenna supports different frequencies; compared with the prior art, when the multi-band is required to support the multi-band, the antenna area can be greatly saved, the space occupied by the antenna can be reduced, and the signal is in the multi-band antenna. There is only one transmission path, and there is no coupling phenomenon caused by multiple transmission paths, so the efficiency of the antenna can be improved.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by hardware or by software plus necessary general hardware platform. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including several The instructions are for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention.

The above disclosure is only a few specific embodiments of the present invention, but the present invention is not limited thereto, and any changes that can be made by those skilled in the art should fall within the protection scope of the present invention.

Claims

Rights request

A multi-band antenna comprising an antenna body, characterized in that

Providing at least one switch on the antenna body;

The switch is for controlling the multi-band antenna to support different frequencies in different states.

The multi-band antenna according to claim 1, wherein the antenna body is provided with a plurality of switches, and a capacitor is provided between adjacent switches.

The multi-band antenna according to claim 1, wherein the switch is specifically configured to control the multi-band antenna to support a lowest frequency in a fully closed state, and control a switch that is closest to the feed point. In order to enable the multi-band antenna to support the highest frequency in an open state, all switches are controlled to enable the multi-band antenna to support other frequencies than the lowest frequency and the highest frequency in a combined state of opening and closing.

A method for implementing a multi-band antenna, comprising: disposing at least one switch on an antenna body of a multi-band antenna, and setting a control signal to control a state of a switch on the antenna body to enable the multi-band antenna Support different frequencies.

5. The method according to claim 4, wherein a plurality of switches are disposed on the antenna body of the multi-band antenna, a capacitance is set between adjacent switches; and a device capacitance is between adjacent switches.

The method according to claim 4, wherein the setting a control signal to control a state of the switch on the antenna body to enable the multi-band antenna to support different frequencies includes:

A low frequency control signal is set to control that all switches on the antenna body are in a closed state, so that the multi-band antenna supports a lowest frequency.

The high frequency control signal is set to control the switch on the antenna body closest to the feed point to be in an open state, so that the multi-band antenna supports the highest frequency.

An intermediate frequency control signal is provided to control all of the switches on the antenna body to be in a combined state of opening and closing, such that the multi-band antenna supports frequencies other than the lowest frequency and the highest frequency.