CN102570028A - System and method for realizing high isolation of antennas between adjacent frequency bands - Google Patents

Abstract

The invention discloses a multi-antenna system for realizing high isolation of antennas between adjacent frequency bands. The tail ends of two antenna units at different frequency bands form a coupling capacitor; the two antenna units are connected with each other by a neutralizing wire; the coupling capacitor and the neutralizing wire form a loop; a parallel resonant circuit/distribution parameter structure is added on the neutralizing wire; and both fi and f0 are less than f2 and greater than f1, wherein the frequency bands to be isolated are f1 and f2, fi is resonant frequency of the loop formed by the coupling capacitor and the neutralizing wire (the parallel resonant circuit is not added), and f0 is resonant frequency of the parallel resonant circuit/distribution parameter structure. When frequency f is less than f0, the parallel resonant circuit/distribution parameter structure shows an inductance characteristic, so that the equivalent inductance of the whole neutralizing wire is improved and the resonant frequency of the loop can be reduced to f1. When the work frequency f is greater than f0, the parallel resonant circuit/distribution parameter structure shows a capacitance characteristic, so that the equivalent inductance of the whole neutral wire is reduced and the resonant frequency of the loop can be increased to be greater than fi. At the same time, the parallel resonant circuit/distribution parameter structure belongs to an open loop, so that good electromagnetic radiation can be generated.

Description

Close on and realize the high system and method for isolating of antenna between frequency range

Technical field

The present invention relates to the multiaerial system of communication, relate in particular to a kind of two and close on the system and method for realizing the high isolation of antenna in the frequency range.

Background technology

In multiaerial system, need to use a plurality of receptions and transmitting antenna.Coupling between the antenna can reduce the radiance of antenna, and influences the performance of whole system thus.Especially in portable terminal, the crack between the antenna is very little, and coupling each other is strong, need adopt isolation technology to eliminate the coupling between the antenna for this reason.

Wherein a kind of is to be employed in to slot on the ground plate or add defective ground (DGS) structure to eliminate the technology that is coupled between the antenna, utilizes groove or defective ground on the ground plate to produce the band inhibition effect, thus the coupling between the suppressing antenna.But ground plate generally needs to be connected with a lot of electric components, and the structure difficulty that change ground plate is bigger, and versatility is poor.

Second kind is the technology that adopts electromagnetic bandgap structure (EBG) to eliminate to be coupled between the antenna, and electromagnetic bandgap structure can suppress surface wave propagation, reduces the coupling between antenna thus.But the EGB structure is too big, is not suitable for being applied in this type of picture mobile phone portable terminal.

The third is that antenna adopts the ultra material of electromagnetism in one section frequency range, to produce the equivalent negative magnetic permeability, thereby makes electromagnetic energy to be sent to another antenna from an antenna, realizes high effect of isolating thus.Or the 4th kind is adopted port to decouple and matching process is eliminated the technology that is coupled between the antenna.That is, a passive decoupling device (directional coupler or branch line coupler) and matching network are added to the port of antenna.But the defective that above-mentioned two kinds of methods exist is: increased the complexity of design, will occupy very big space as passive device etc., also do not utilized to be applied in this type of picture mobile phone portable terminal.

At application number is to disclose a kind of " adopting coupling element to improve the system and method for antenna isolation " in 20088000128.0; Antenna system is disclosed in this application file; It comprises and first antenna element, itself and the second antenna element mutual, and the mutual coupling between first and second antenna elements makes and on second antenna element, produces first electric current; And coupling element is at least partly between first and second antenna elements; The wherein coupling element and the first and second antenna element mutual coupling, and coupling element is configured on second antenna element to produce second electric current, and it at least can partial offset first electric current.In above-mentioned patent application principle does not openly only specifically indicate and how to accomplish antenna isolation.

Yet along with the fast development of radio communication, for speed and the quality that improves transfer of data, multiple-input and multiple-output (MIMO) technology is used.That is to say that along with sustainable development in recent years, the MIMO technology is applied to various communication systems more and more.And, or formulated a plurality of wireless communication standards in order to satisfy various application.The working frequency range of these standards is different, but because the scarcity of electromagnetic spectrum, the working frequency range of a lot of standards closes on again very much, like the CDMA800 that is using at present, and GSM900. and the U.S. also gives LTE with the frequency allocation of 700MHz.Can predict, in the near future, have increasing standard and adopt the MIMO technology, and the working frequency range of these standards can be very near.

And MIMO Technology Need mobile device has the identical but separate antenna of two or more working methods.In mobile device, in order to save the space, the frequency range of closing on generally all is to adopt an antenna to cover.If adopt the MIMO technology, then will need two or many can cover this two antennas that close on frequency range.But this time, very big coupling will take place in these antenna in these two frequency ranges.How to realize all in these two frequency ranges of closing on that good isolation is to need the urgent problem that solves.And existing technology all can only realize the height isolation of single frequency range and arrowband.

Summary of the invention

First purpose of the present invention is to provide a kind of closing on to realize the high system that isolates of antenna in the frequency range, isolates with the height that can only realize single frequency range and arrowband in the solution prior art, and can not realize that two close on the technical problem that realizes the high isolation of antenna in the frequency range.

Second purpose of the present invention is to provide a kind of closing on to realize the high method of isolating of antenna in the frequency range, isolates with the height that can only realize single frequency range and arrowband in the solution prior art, and can not realize that two close on the technical problem that realizes the high isolation of antenna in the frequency range.

A kind of close between frequency range realized the high multiaerial system of isolating of antenna, and the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance, and between two antenna elements with in be connected with line; Coupling capacitance with the neutralization line form a loop, and in line on add antiresonant circuit/distributed constant structure, and; F1 < fi < f2; F1 f0 f2, wherein, it is f1 and f2 that desire produces two frequency ranges of isolating; Fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of antiresonant circuit/>distributed constant structure.

A kind of closing on realized the high method of isolating of antenna between frequency range, may further comprise the steps:

One circuit is provided: the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance, and between two antenna elements with in is connected with line, the coupling capacitance and the line that neutralizes form a loop; And in line on add antiresonant circuit/distributed constant structure, and, f1 < fi < f2; F1 f0 f2, wherein, it is f1 and f2 that desire produces two frequency ranges of isolating; Fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of antiresonant circuit/>distributed constant structure;

At the operating frequency f that the input of the port of antenna element changes, the degree of coupling of the frequency ranges that test two is isolated in advance finds and satisfies the operating frequency that meets insulation request.

The master who supposes antenna is coupled as capacitive coupling, and coupling capacitance is C<sub >c</sub>, coupling inductance is L<sub >c</sub>, the high isolation just occurs in<img file="DEST_PATH_IMAGE001.GIF" he="29" img-content="drawing" img-format="GIF" inline="no" orientation="portrait" wi="120" />. as operating frequency f<during f0, antiresonant circuit/distributed constant structure externally shows as inductance characteristic, reduces the current resonance frequency fi in loop, as operating frequency f>Antiresonant circuit during f0/distributed constant structure externally shows as capacitance characteristic, the current resonance frequency fi in rising loop.

Compared with prior art, the present invention can close on the height isolation that frequency range realizes antenna at two, keeps the good radiance of antenna simultaneously again.

Description of drawings

Fig. 1 is a kind of principle exemplary plot that realizes the high multiaerial system of isolating of antenna between frequency range of closing on;

Fig. 2 A is the structural representation that antenna element adopts the high multiaerial system of isolating of realization of C type monopole antenna, and Fig. 2 B is the enlarged drawing of the antiresonant circuit part in the structure, and Fig. 2 C is that ground plate is at the base lower surface sketch map;

Fig. 3 is not for adopting in the resonant mode simulation result with the structure of collimation method;

Fig. 4 is for adopting in the tradition and the simulation result of the structure of collimation method;

Fig. 5 is for adopting in the resonant mode and the simulation result of the structure of collimation method;

Fig. 6 is the another kind of principle exemplary plot that realizes the high multiaerial system of isolating of antenna between frequency range of closing on.

Fig. 7 is the enlarged drawing of the antiresonant circuit part in the another kind of structure.

Embodiment

Below in conjunction with accompanying drawing, specify the present invention.

Embodiment 1

The present invention proposes in a kind of new method-resonant mode and collimation method, and the end of two antennas has a coupling, in general is capacitive coupling.And in line be one section thin lead, be equivalent to introduce inductance coupling high.Inductance coupling high and capacitive coupling form a loop.When the resonance of this loop (establishing resonance frequency is fi), for the port of antenna, just as having produced a band stop filter.Therefore, can realize that one is well isolated in this frequency range.With traditional in different with collimation method, this method in line in added antiresonant circuit.

See also Fig. 1, a kind of closing on realized the high multiaerial system of isolating of antenna between frequency range, and the not end that is positioned at twoantenna elements 5 of different frequency range forms acoupling capacitance 1; And between twoantenna elements 5 with in is connected with line 2,coupling capacitance 1 and thin wire (or in claiming and line) 2 formation, one loop, and in and add antiresonant circuit on the line 2; And, f1 < fi < f2, f1 < f0 < f2; Wherein, Two frequency ranges that desire produce to be isolated are f1 and f2, fi becoupling capacitance 1 with in form the resonance frequency in a loop with line 2, f0 is the resonance frequency of antiresonant circuit.In Fig. 1, antiresonant circuit comprises the electric capacity 4 and inductance 3 of a parallel connection, but the present invention is not limited thereto, and any equivalent electric circuit can.

The master who supposes antenna is coupled as capacitive coupling, and coupling capacitance is C_c, coupling inductance is L_c, the high isolation just occurs in. work as frequency f<during f0, antiresonant circuit externally shows as inductance characteristic, improves with the equivalent inductance of line in therefore whole.Therefore can be reduced to the resonance frequency in loop less than fi.As operating frequency f>during f0, antiresonant circuit externally shows as capacitance characteristic, reduces with the equivalent inductance of line in therefore whole, therefore can raise the resonance frequency in loop for greater than fi.Simultaneously, because this resonant tank belongs to open loop, therefore can produce good electromagnetic radiation.That is antiresonant circuit provides a reactance with frequency change, with this change whole in the equivalent inductance of line, thereby the resonance frequency in loop changes.

Antenna element can be C shape monopole antenna, dipole antenna, planar inverted-F antenna, one of them of microstrip antenna.

Antenna element is that embodiment explains the present invention with C type monopole antenna.

See also Fig. 2 A, it adopts the structural representation of the high multiaerial system of isolating of realization of C type monopole antenna for antenna element.Fig. 2 B is the enlarged drawing of the antiresonant circuit part in the structure.Fig. 2 A is atsubstrate 601 upper surfaces, and Fig. 2 C is aground plate 701, atsubstrate 601 lower surfaces.

Two C type monopole antennas are oppositely arranged on a substrate 601,101,201 and do not hold and just form a coupling capacitance.And (mainly be meant the stage casing of C type monopole antenna 101,201) between two C type monopole antennas with in be connected with line 402; Coupling capacitance with in form a loop with line 402; And in line on add antiresonant circuit 501, antiresonant circuit 501 comprises theelectric capacity 801 andinductance 901 of parallel connection.

Based on above-mentioned circuit, a kind of closing on realizes between frequency range that the high method of isolating of antenna may further comprise the steps:

At the operating frequency f that the input of the port of antenna element changes, utilize the degree of coupling of the frequency ranges that emulation testing two isolates in advance, find and satisfy the operating frequency that meets insulation request.

And; As operating frequency f < during f0; Antiresonant circuit/distributed constant structure externally shows as inductance characteristic, reduces the current resonance frequency fi in loop, as operating frequency f>during f0 in; Antiresonant circuit/distributed constant structure externally shows as capacitance characteristic, the current resonance frequency fi in rising loop.Simultaneously, because this resonant tank belongs to open loop, therefore can produce good electromagnetic radiation.

In order to verify said method, working frequency range LTE700 (746-756MHz) that is designed and GSM850 (869-894MHz), the isolation in this connects frequency range need be less than-15dB, and radiation efficiency is greater than 40%.We further with our structure with adopt in the structure of line and adopt in the tradition structure with line to compare.As shown in Figure 3 in adopting with the simulation result of the structure of line, can find out that effective working frequency range of antenna is positioned at 650MHz, and coupling has herein reached-3dB.Adopt in the tradition with the simulation result of the structure of collimation method as shown in Figure 4ly, can find out that effective working frequency range of antenna is positioned at 850MHz, and coupling can be less than-15dB herein.But also can find out, adopt only can in a frequency range, produce effective isolation and radiation with collimation method in traditional, can't satisfy the requirement of two two-bands of closing on.Adopt in the resonant mode that we propose with the simulation result of the structure of collimation method as shown in Figure 5ly, can find out that in two frequency ranges of closing on (LTE700 and GSM850), antenna not only can have good radiation, and the isolation of antenna is also less than-15dB.

Embodiment two

See also Fig. 6, a kind of closing on realized the high multiaerial system of isolating of antenna between frequency range, and the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance; And between two antenna elements with in is connected with line, coupling capacitance forms a loop with the neutralization line, and in line on adding distributed capacitor 8 and distributed inductance 9 (seeing also Fig. 7); And, f1 < fi < f2, f1 < f0 < f2; Wherein, It is f1 and f2 that desire produces two frequency ranges of isolating, and fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of distributed constant structure.

Relation below the resonance frequency f0 of distributed constant structure and the resonance frequency fi in loop exist:

< during f0, the distributed constant structure externally shows as inductance characteristic, reduces the current resonance frequency fi in loop as operating frequency f; As operating frequency f>during f0, the distributed constant structure externally shows as capacitance characteristic, and the current resonance frequency fi in rising loop, f are the frequency that inputs to the antenna element port.

More than the disclosed several specific embodiments that are merely the application, but the application is not limited thereto, any those skilled in the art can think variation, all should drop in the application's the protection range.

Claims (9)

1. one kind is closed on the multiaerial system that realizes the high isolation of antenna between frequency range, it is characterized in that the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance; And between two antenna elements with in is connected with line, coupling capacitance forms a loop with the line that neutralizes, and in and add antiresonant circuit on the line; And, f1 < fi < f2, f1 < f0 < f2; Wherein, It is f1 and f2 that desire produces two frequency ranges of isolating, and fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of antiresonant circuit.

2. the system of claim 1 is characterized in that, relation below the resonance frequency f0 of antiresonant circuit and the resonance frequency fi in loop exist:

< during f0, antiresonant circuit externally shows as inductance characteristic, reduces the current resonance frequency fi in loop as operating frequency f;

As operating frequency f>during f0, antiresonant circuit externally shows as capacitance characteristic, and the current resonance frequency fi in rising loop, f are the frequency that inputs to the antenna element port.

3. the system of claim 1 is characterized in that, said antiresonant circuit further comprises the electric capacity and an inductance of parallel connection.

4. the system of claim 1 is characterized in that, antenna element is C shape monopole antenna, dipole antenna, planar inverted-F antenna, one of them of microstrip antenna.

5. one kind is closed on the multiaerial system that realizes the high isolation of antenna between frequency range, it is characterized in that the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance; And between two antenna elements with in is connected with line, coupling capacitance forms a loop with the neutralization line, and in and adding distributed constant structure on the line; And, f1 < fi < f2, f1 < f0 < f2; Wherein, It is f1 and f2 that desire produces two frequency ranges of isolating, and fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of distributed constant structure.

6. system as claimed in claim 4 is characterized in that, antenna element is C shape monopole antenna, dipole antenna, planar inverted-F antenna, one of them of microstrip antenna.

7. system as claimed in claim 4 is characterized in that, relation below the resonance frequency f0 of distributed constant structure and the resonance frequency fi in loop exist:

< during f0, the distributed constant structure externally shows as inductance characteristic, reduces the current resonance frequency fi in loop as operating frequency f;

As operating frequency f>during f0, the distributed constant structure externally shows as capacitance characteristic, and the current resonance frequency fi in rising loop, f are the frequency that inputs to the antenna element port.

8. one kind is closed on the method that realizes the high isolation of antenna between frequency range, it is characterized in that, may further comprise the steps:

One circuit is provided: the not end that is positioned at two antenna elements of different frequency range forms a coupling capacitance, and between two antenna elements with in is connected with line, the coupling capacitance and the line that neutralizes form a loop; And in line on add antiresonant circuit/distributed constant structure, and, f1 < fi < f2; F1 f0 f2, wherein, it is f1 and f2 that desire produces two frequency ranges of isolating; Fi is the resonance frequency that coupling capacitance and neutralization line form a loop, and f0 is the resonance frequency of antiresonant circuit/>distributed constant structure;

At the operating frequency f that the input of the port of antenna element changes, the degree of coupling of the frequency ranges that test two is isolated in advance finds and satisfies the operating frequency that meets insulation request.

9. method as claimed in claim 7 is characterized in that, supposes that the master of antenna is coupled as capacitive coupling, and coupling capacitance is C<sub >c</sub>, coupling inductance is L<sub >c</sub>, the high isolation just occurs in<img file="DEST_PATH_IMAGE002.GIF" he="29" id="ifm0001" img-content="drawing" img-format="GIF" inline="no" orientation="portrait" wi="120" />, as operating frequency f<during f0, antiresonant circuit/distributed constant structure externally shows as inductance characteristic, reduces the current resonance frequency fi in loop, as operating frequency f>During f0, antiresonant circuit/distributed constant structure externally shows as capacitance characteristic, the current resonance frequency fi in rising loop.

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