A kind of Electro Magnetic Compatibility method that solves the Miniature Terminal antenna for mobile phone
Technical field
The present invention relates to the Miniature Terminal mobile phone, relate in particular to a kind of Electro Magnetic Compatibility method that solves the Miniature Terminal antenna for mobile phone.
Background technology
At present, because the antenna of Miniature Terminal often adopts common printed circuit antenna form or monopole antenna.This class antenna is to satisfy common OTA(Over The Air) requirement, but at Electro Magnetic Compatibility index-SAR(Specific Absorption Rate) and HAC(Hearing Aid compatibility), but nearly all can not satisfy.This also is the bottleneck of present Miniature Terminal antenna development.SAR is meant will produce induction field in the human body under the effect of external electromagnetic field.Because the various organs of human body are lossy dielectric, so electromagnetic field will produce electric current in the body, causes absorbing and the dissipation electromagnetic energy.The RF energy of antenna for mobile phone institute radiation can be absorbed by the body and produce heat, and transmits by the body heat regulation system of human body.The RF electromagnetic wave energy ratio that tissue absorbed or consumed of unit mass just is called SAR.Being commonly referred to as electro-magnetic wave absorption ratio or specific absorption rate, is that the electromagnetic wave energy of mobile phone or wireless product absorbs ratio, and unit is W/kg.The test of SAR is the radio wave energy that produces via mobile phone, and measuring actually by testing equipment, how many electromagenetic wave radiations human body (just brain or health) has absorbed.The HAC test index is that mobile phone can produce mutual interference mutually in use with hearing-aid device, therefore, Federal Communications Committee (FCC) requires test and improves the compatibility of mobile phone and hearing-aid device, help is worn the hearing aids personage in the process of making a phone call, the electromagnetic interference (Electromagnetic Interference) of avoiding operating handset to produce.
What SAR studied is under the effect of external electromagnetic field, will produce induction field in the human body.Because the various organs of human body are lossy dielectric, so electromagnetic field will produce electric current in the body, causes absorbing and the dissipation electromagnetic energy.For example people can follow the air time long more in the process of making a phone call, and human brain can produce the dizzy brain phenomenon of dusk, the problem of SAR is about to research that Here it is.HAC research be Electro Magnetic Compatibility index when weighing antenna for mobile phone with the hearing aids co-operation owing to wear in the process that the hearing aids personage makes a phone call through being everlasting, be subjected to the electromagnetic field of mobile phone and interfering with each other of hearing aids, can allow the unintelligible unusually of change of conversing.And in the process that these crowds are conversing, the electromagnetic field that mobile phone produces can be coupled on the hearing aids, allows the caller produce noise.And these phenomenons HAC problem that will solve just.
At present, be used for the antenna of Miniature Terminal, antenna body is dipole antenna normally.But along with mobile miniaturization terminal develops toward lightening direction, the space of leaving the miniaturization terminal antenna for is also more and more littler, at this time uses monopole antenna can satisfy the communication need of miniaturization terminal equipment, also can satisfy the demand of multifrequency and wideband.Along with the proposition of Electro Magnetic Compatibility index, not only the antenna of Miniature Terminal there is the requirement of emission and acceptance, also have the requirement of SAR and HAC.Here it is has produced the contradiction of far-field radiation and near-field thermal radiation.
At present, do not have effective and lower-cost solution in the industry, general solution all is by reducing the performance index of far-field radiation, just reduce the index of OTA, exchanging the up to standard of near field SAR and HAC for.But run into the index request of international well-known operator, not only require OTA but also require SAR and HAC, often just powerless.This has also just become the development bottleneck of present miniaturization terminal antenna.
Summary of the invention
The problem that the present invention need solve provides and a kind ofly makes antenna volume do forr a short time under the prerequisite of Electro Magnetic Compatibility and satisfy SAR, HAC index and the Electro Magnetic Compatibility method of the solution Miniature Terminal antenna for mobile phone that the OTA test specification requires satisfying.
To achieve these goals, the present invention designs a kind of Electro Magnetic Compatibility method that solves the Miniature Terminal antenna for mobile phone, choose the antenna of unipole antenna as the Miniature Terminal mobile phone, in the empty regions of the unipole antenna of pcb board, be printed with lead, the ground end of the pcb board in one end of described lead and the non-empty regions is connected, the other end extends in empty regions, and described lead can effectively disperse the electric field of HAC and magnetic field focus to distribute, thereby has solved HAC index request in the Electro Magnetic Compatibility; On the bonnet of Miniature Terminal mobile phone, paste conductive fabric or spray conductive paint, and make it to be connected, thereby effectively solved SAR index request in the Electro Magnetic Compatibility with the ground end of PCB; The match circuit of tuned antenna makes the emitting performance of antenna and accepts performance to obtain more satisfactory state, and the SAR and the HAC requirement of near-field thermal radiation are satisfied in both requirements of the OTA of the far-field radiation of Man Zuing again.
More preferably, described lead is to draw at empty regions distributing point rightabout.
More preferably, described lead is " L " type.
More preferably, described conductor width is 2~4mm.
More preferably, the length of described lead is 1/3
To 1/5
Wavelength.
More preferably, the length of described lead is 25~40mm.
Described in the present invention conductive fabric or conductive paint are by connecting by direct contact or being of coupled connections.Described being of coupled connections is meant conductive fabric or the liftoff segment distance of conductive paint, and the form by electromagnetic coupled tells on.
Described in the present invention conductive fabric or conductive paint are to be arranged on the projected position of the antenna empty regions on the pcb board.
Described in the present invention match circuit is ∏ type multiple-series-parallel form match circuit.
The tuning manner of described match circuit is inductance capacitance and place parallel way in the present invention.
The invention solves the emc issue of antenna for mobile phone, satisfy SAR and HAC index, the utmost point
The earth has reduced the Miniature Terminal antenna volume, under the index that satisfies SAR and HAC, can satisfy the requirement of OTA test specification again.It is the Miniature Terminal communication product of representative that the present invention is used for the mobile phone, is applicable in the products such as mobile phone, MID.
The present invention has following beneficial effect:
1. it is convenient to realize, structure is simple and clear, and can effectively improve the Electro Magnetic Compatibility of antenna for mobile phone.
2. solved the contradictory relation of far-field radiation OTA and near-field thermal radiation in the traditional approach.
3. solution is with low cost, easily realizes.
Description of drawings:
Fig. 1 is the antenna structure view that the present invention solves the Electro Magnetic Compatibility method of Miniature Terminal antenna for mobile phone.
Embodiment
For the ease of those skilled in the art's understanding, structural principle of the present invention is described in further detail below in conjunction with specific embodiment and accompanying drawing:
As shown in Figure 1, a kind of Electro Magnetic Compatibility method that solves the Miniature Terminal antenna for mobile phone.Be printed with lead 4 in its
empty regions 3 on the
pcb board 1 of unipole antenna, the ground end of the pcb board in one end of described lead 4 and the
non-empty regions 2 is connected, the other end extends in
empty regions 3, described lead 4 can effectively disperse the electric field of HAC and magnetic field focus to distribute, thereby has solved HAC index request in the Electro Magnetic Compatibility.Described lead 4 is to draw at
empty regions 3 distributing
points 5 rightabouts, and described lead 4 is " L " type.Lead 4 width controls are controlled to be in 2~4mm scope.The length of lead 4 is 1/3
To 1/5
Wavelength, or the length of lead 4 is 25~40mm.
The present invention solves the Electro Magnetic Compatibility method of Miniature Terminal antenna for mobile phone, on the bonnet of the projected position of the antenna empty regions on the pcb board, paste conductive fabric or spray conductive paint, and make it to be connected with the ground end of PCB, its area size is half area of battery cover.Thereby effectively solved SAR index request in the Electro Magnetic Compatibility, its cardinal principle is offset the forward current of mainboard for producing reverse current, can relatively effectively reduce SAR, improves Electro Magnetic Compatibility.
The Electro Magnetic Compatibility method that the present invention solves the Miniature Terminal antenna for mobile phone is the match circuit by tuned antenna also, make the emitting performance of antenna and accept performance and obtain more satisfactory state, the SAR and the HAC requirement of near-field thermal radiation are satisfied in both requirements of the OTA of the far-field radiation of Man Zuing again.The present invention adopts the form match circuit of the multiple-series-parallel connection of ∏ type, and its tuning manner is inductance capacitance and place parallel way.
The empty regions of indication of the present invention: refer to not have among the PCB zone of PCB ground covering, and also do not have other electronic devices in the zone.
The invention has gone out a kind of from solving the Electro Magnetic Compatibility interference of Miniature Terminal antenna in essence, improves SAR﹠amp; The HAC index is improved handset capability, improves the technical scheme of Miniature Terminal antenna for mobile phone.At present domesticly there is no other theoretical foundation is arranged, can reduce SAR, satisfy the effective ways of HAC index again.
Foregoing is preferred embodiment of the present invention only, is not to be used to limit embodiment of the present invention, and those skilled in the art are according to design of the present invention, and appropriate adaptation of having done or modification all should be within protection scope of the present invention.