多模移动终端中天线技术的研究
摘要
随着移动通信技术的演进发展，2G/3G/LTE等多制式移动通信网络共存将成为必然趋势。为满足用户漫游及多种业务需求，移动终端产品需要有支持多模、多频段的多天线。同时由于在移动终端上尺寸受限，因此还必须使天线尽量小型化，提高天线集成度。天线隔离度对整个MIMO通信系统的分集增益起着重大的影响，当隔离度不佳时，系统的分集增益大大降低，因此高隔离度、高集成度、多模、多频段的多天线将成为未来移动终端天线研究的主要方向，本文主要研究高隔离度多天线与高集成度多频天线。
在提高天线隔离度的研究方面，本文提出了新型的平面倒F天线结构，采用了非接触的容性馈电与容性加载技术，使能量不能直接通过馈源或短路壁流入接地板，从而降低了多天线之间的耦合，通过仿真和实物测试证明了该天线结构的正确性。在工作频带内天线隔离度大于25dB，包络相关系数小于0.012，满足MIMO通信系统对包络相关系数小于0.5的要求。同时该结构与平衡结构类似，与非平衡结构的天线相比，接地板不再作为天线系统的一部分参与电磁波辐射，因此接地板的尺寸等外部因素对天线性能影响更小。
在实现天线多频特性的研究方面，本文在充分研究平面倒F天线短路壁位置与宽度对天线谐振频率影响的基础上，提出了通过改变其短路壁位置实现频率重构的方法，其天线结构是：在单层、矩形微带天线侧面上加载多个通断状态可控的短路壁（在短路壁上附加开关器件实现通断状态可控），通过控制短路壁上开关器件的通断状态，有选择地使其中一个短路壁接通，同时其他短路壁断开，辐射片上的电流则通过此短路壁流入接地板。选择不同的短路壁接通，电流则通过不同路径流入接地板，因此，随着电流路径的改变，天线工作频率也会改变，并且天线可以工作在一个很宽的频带范围内。同时提出短路壁可重构天线工作频率的估算公式和设计方法。最后通过仿真和实物测试证明了短路壁可重构天线结构的正确性。
As the evolution of the mobile communication technology, the coexistenceof2G/3G/LTE formats will become an inevitable trend. To meet the userroaming and the needs of the business, mobile terminal product needs tosupport multimode, multimode and multiband antenna. As the mobile terminalis limited in size, it must make the antenna be miniaturization, and enhancethe antenna integration. The antenna isolation has a major influence on thediversity gain of the whole MIMO communication system, when the isolationis bad, the diversity gain of system will be greatly reduced. So the highisolation、high integration、multimode and multiband antenna will become themain research direction of the future mobile terminal antenna. This papermainly studies the high isolation degree antenna and the high isolationmultiband.
In the study of enhance the isolation degree of antenna, this paper putsforward the new type of plane fall F antenna structure, it makes that energycan’t flow into the GND directly through the feed source or short wall byadopting non-contact capacitive feed and capacitive load, then it can reducecoupling of the multiple antenna. The antenna isolation is larger than25dB inthe operating frequency range, the envelope correlation coefficient is less than0.012, and it meets the requirement that the envelope correlation coefficientis less than the of0.5in the MIMO communication system. At the same timethe structure is a balanced structure, GND is no more a part of a antennasystem to participate in electromagnetic radiation compared with thenon-equilibrium structure of antenna, so the size of GND and other externalfactors have less impact on the antenna performance.
On the basis of studying the planar inverted F antenna short circuit walllocation and width of the antenna resonant frequency fully, this paperproposing that it can realize frequency reconstruction by changing theposition of the short wall, the antenna structure is: to load multiple off state-controlled short-circuit wall on the single layer, and the side of therectangular microstrip antenna(it can realize on-off state by attaching switching devices controlled in the short-circuit walls), through the control ofshort-circuit wall switch device off state, to make one short-circuit wall beconnected and others be switched off at the same time, then the current on theradiation patch can flow into the GND. Current can flow into the GND byusing different methods by choosing different short-circuit wall to beconnected, so the antenna operating frequency will change with the change ofthe current path, and the antenna can work in a wide frequency range. Thenproduce the estimation formula of frequency and design methods of the shortwall reconfigurable antenna.
在提高天线隔离度的研究方面，本文提出了新型的平面倒F天线结构，采用了非接触的容性馈电与容性加载技术，使能量不能直接通过馈源或短路壁流入接地板，从而降低了多天线之间的耦合，通过仿真和实物测试证明了该天线结构的正确性。在工作频带内天线隔离度大于25dB，包络相关系数小于0.012，满足MIMO通信系统对包络相关系数小于0.5的要求。同时该结构与平衡结构类似，与非平衡结构的天线相比，接地板不再作为天线系统的一部分参与电磁波辐射，因此接地板的尺寸等外部因素对天线性能影响更小。
在实现天线多频特性的研究方面，本文在充分研究平面倒F天线短路壁位置与宽度对天线谐振频率影响的基础上，提出了通过改变其短路壁位置实现频率重构的方法，其天线结构是：在单层、矩形微带天线侧面上加载多个通断状态可控的短路壁（在短路壁上附加开关器件实现通断状态可控），通过控制短路壁上开关器件的通断状态，有选择地使其中一个短路壁接通，同时其他短路壁断开，辐射片上的电流则通过此短路壁流入接地板。选择不同的短路壁接通，电流则通过不同路径流入接地板，因此，随着电流路径的改变，天线工作频率也会改变，并且天线可以工作在一个很宽的频带范围内。同时提出短路壁可重构天线工作频率的估算公式和设计方法。最后通过仿真和实物测试证明了短路壁可重构天线结构的正确性。
As the evolution of the mobile communication technology, the coexistenceof2G/3G/LTE formats will become an inevitable trend. To meet the userroaming and the needs of the business, mobile terminal product needs tosupport multimode, multimode and multiband antenna. As the mobile terminalis limited in size, it must make the antenna be miniaturization, and enhancethe antenna integration. The antenna isolation has a major influence on thediversity gain of the whole MIMO communication system, when the isolationis bad, the diversity gain of system will be greatly reduced. So the highisolation、high integration、multimode and multiband antenna will become themain research direction of the future mobile terminal antenna. This papermainly studies the high isolation degree antenna and the high isolationmultiband.
In the study of enhance the isolation degree of antenna, this paper putsforward the new type of plane fall F antenna structure, it makes that energycan’t flow into the GND directly through the feed source or short wall byadopting non-contact capacitive feed and capacitive load, then it can reducecoupling of the multiple antenna. The antenna isolation is larger than25dB inthe operating frequency range, the envelope correlation coefficient is less than0.012, and it meets the requirement that the envelope correlation coefficientis less than the of0.5in the MIMO communication system. At the same timethe structure is a balanced structure, GND is no more a part of a antennasystem to participate in electromagnetic radiation compared with thenon-equilibrium structure of antenna, so the size of GND and other externalfactors have less impact on the antenna performance.
On the basis of studying the planar inverted F antenna short circuit walllocation and width of the antenna resonant frequency fully, this paperproposing that it can realize frequency reconstruction by changing theposition of the short wall, the antenna structure is: to load multiple off state-controlled short-circuit wall on the single layer, and the side of therectangular microstrip antenna(it can realize on-off state by attaching switching devices controlled in the short-circuit walls), through the control ofshort-circuit wall switch device off state, to make one short-circuit wall beconnected and others be switched off at the same time, then the current on theradiation patch can flow into the GND. Current can flow into the GND byusing different methods by choosing different short-circuit wall to beconnected, so the antenna operating frequency will change with the change ofthe current path, and the antenna can work in a wide frequency range. Thenproduce the estimation formula of frequency and design methods of the shortwall reconfigurable antenna.
引文
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[2] Lin M T, Chung S J. A compact MIMO antenna system with three closelyspaced multi-band antennas for WLAN application [C]. APMC2007, Bangkok,IEEE Press,2007,1-4.
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[6] Chi G M, Li B H, Qi D S. A dual-frequency antenna fed by CPW [C].APSURSI2005, Washington, IEEE Press,2005,459-462.
[7] Yablonovitch E. Inhibited spontaneous emission in solid state physicsandelectronics [J], Phy. Rev. Lett.,1987,58,2059-2062.
[8] Gao Yue, Chen X D, Ying Z N, Parini C. Design and performanceInvestigation of a dual-element PIFA array at2.5GHz for MIMO terminal [J].IEEE Trans. Antennas Propag.,2007,55(12),3433-3441.
[9] Kingsley S. Advances in handset antenna design [J]. RF design,2005,16-22.
[10] Ide J M, Kingsley S, O'Keefe S G, Saario S A, Schlub R W, Collins B S.Balanced-unbalanced antennas. W.O.Patent, WO2006082382, August10,2006.
[11] Rowson S, Poilasne G, Desclos L. Isolated magnetic dipole antenna:application to GPS [J]. Microwave and Optical Technology Letters,2004,41(6),449-451.
[12] Poilasne G, Rowson S, Desclos L. Multiband capacitively loadedmagnetic dipole [J]. Microwave and Optical Technology Letters,2004,43(6),475-478.
[13] Rowson S. Optimizing performance when integrating multiple antennas[J]. Antenna Systems&Technologies,2006,18-19.
[14] Diallo A, Luxey C, Thuc P L, Staraj R, Kossiavas G. Study and reductionof the mutual coupling between two mobile phone PIFAs operating in theDCS1800and UMTS bands [J]. IEEE Trans. Antennas Propag.,2006,54(11),3063-3074.
[15] Komulainen M, Berg M, Jantunen H, Salonen E T, Charles Free. Afrequency tuning method for a planar inverted-F antenna [J]. IEEE Trans.Antennas Propagat.,2008,56(4),944-950.
[16] Nguyen V A, Bhatti R A, Park S O. Simple PIFA-Based Tunable InternalAntenna for Personal Communication Handsets [J]. IEEE Ant. Wirel. Prop.Lett.,2008,7,130-133.
[17] Fankem B K, Melde K L, Zhou Z. Frequency reconfigurable planarinverted F antenna (PIFA) with software-defined match control [C], IEEEAntennas and Propag. Soc. Int. Symp., Hawaii, IEEE Press,2007,81-84.
[18] Hu W, Ismail M Y, Cahill R, Gamble H S, Dickie R, Fusco V F, Linton D,Rea S P, Grant N. Tunable liquid crystal reflectarray patch element [J].Electron. Lett.,2006,49(9),509-511.
[19] Bai M D. Core technology and analysis of802.11N [C]. InternationalConference on Electric Information and Control Engineering2011, Wuhan,China, IEEE Press,2011,1261-1265.
[20] Fang S T, Yeh S H, Wong K L. Dual-band planar inverted F antenna forGSM/DCS mobile phones [C]. IEEE Trans. Antennas Propag.,2003,51(5),1124-1126.
[21] Rowell C R, Murch R D. A capacitively loaded PIFA for compact mobiletelephone handsets [C]. IEEE Trans. Antennas Propag.,1997,54(5),837-842.
[22] Vaughan R G, Andersen J B. Antenna diversity in mobile communications[C]. IEEE Transactions on Vehicular Technology,1978,36(4),149-172.
[23] Ko S C K, Murch R D. Compact integrated diversity antenna for wirelesscommunications [C]. IEEE Trans. Antennas Propag.,2001,49(6),954-960.
[24] Taga T. Analysis of mean effective gain of mobile antennas in landmobile radio environments [C]. IEEE Transactions on Vehicular Technology,1990,39(2),117-123.
[25]巫正中. RF-MEMS天线理论、建模仿真及特性研究[D].2002,重庆大学博士学位论文.
[26]杨雪松.微带可重构天线研究[D].2006,电子科技大学博士学位论
[2] Lin M T, Chung S J. A compact MIMO antenna system with three closelyspaced multi-band antennas for WLAN application [C]. APMC2007, Bangkok,IEEE Press,2007,1-4.
[3] Christos O Z, Bernhard R. A3-port an tenna for MIMO applications [C].INICA2007, Munich, IEEE Press,2007,49-52.
[4] Karaboikis M, Soras C, Tsachtsiris G, Makios V. Compact dual-printedinverted-F antenna diversity systems for portable wireless devices [J]. IEEEAnt. Wirel. Prop. Lett.,2004,3,9-14.
[5] Min K S, Kim D J, Moon Y M. Improved MIMO antenna by mutualcoupling suppression between elements [C]. ECWT2005, Paris, IEEE Press,2005,125-128.
[6] Chi G M, Li B H, Qi D S. A dual-frequency antenna fed by CPW [C].APSURSI2005, Washington, IEEE Press,2005,459-462.
[7] Yablonovitch E. Inhibited spontaneous emission in solid state physicsandelectronics [J], Phy. Rev. Lett.,1987,58,2059-2062.
[8] Gao Yue, Chen X D, Ying Z N, Parini C. Design and performanceInvestigation of a dual-element PIFA array at2.5GHz for MIMO terminal [J].IEEE Trans. Antennas Propag.,2007,55(12),3433-3441.
[9] Kingsley S. Advances in handset antenna design [J]. RF design,2005,16-22.
[10] Ide J M, Kingsley S, O'Keefe S G, Saario S A, Schlub R W, Collins B S.Balanced-unbalanced antennas. W.O.Patent, WO2006082382, August10,2006.
[11] Rowson S, Poilasne G, Desclos L. Isolated magnetic dipole antenna:application to GPS [J]. Microwave and Optical Technology Letters,2004,41(6),449-451.
[12] Poilasne G, Rowson S, Desclos L. Multiband capacitively loadedmagnetic dipole [J]. Microwave and Optical Technology Letters,2004,43(6),475-478.
[13] Rowson S. Optimizing performance when integrating multiple antennas[J]. Antenna Systems&Technologies,2006,18-19.
[14] Diallo A, Luxey C, Thuc P L, Staraj R, Kossiavas G. Study and reductionof the mutual coupling between two mobile phone PIFAs operating in theDCS1800and UMTS bands [J]. IEEE Trans. Antennas Propag.,2006,54(11),3063-3074.
[15] Komulainen M, Berg M, Jantunen H, Salonen E T, Charles Free. Afrequency tuning method for a planar inverted-F antenna [J]. IEEE Trans.Antennas Propagat.,2008,56(4),944-950.
[16] Nguyen V A, Bhatti R A, Park S O. Simple PIFA-Based Tunable InternalAntenna for Personal Communication Handsets [J]. IEEE Ant. Wirel. Prop.Lett.,2008,7,130-133.
[17] Fankem B K, Melde K L, Zhou Z. Frequency reconfigurable planarinverted F antenna (PIFA) with software-defined match control [C], IEEEAntennas and Propag. Soc. Int. Symp., Hawaii, IEEE Press,2007,81-84.
[18] Hu W, Ismail M Y, Cahill R, Gamble H S, Dickie R, Fusco V F, Linton D,Rea S P, Grant N. Tunable liquid crystal reflectarray patch element [J].Electron. Lett.,2006,49(9),509-511.
[19] Bai M D. Core technology and analysis of802.11N [C]. InternationalConference on Electric Information and Control Engineering2011, Wuhan,China, IEEE Press,2011,1261-1265.
[20] Fang S T, Yeh S H, Wong K L. Dual-band planar inverted F antenna forGSM/DCS mobile phones [C]. IEEE Trans. Antennas Propag.,2003,51(5),1124-1126.
[21] Rowell C R, Murch R D. A capacitively loaded PIFA for compact mobiletelephone handsets [C]. IEEE Trans. Antennas Propag.,1997,54(5),837-842.
[22] Vaughan R G, Andersen J B. Antenna diversity in mobile communications[C]. IEEE Transactions on Vehicular Technology,1978,36(4),149-172.
[23] Ko S C K, Murch R D. Compact integrated diversity antenna for wirelesscommunications [C]. IEEE Trans. Antennas Propag.,2001,49(6),954-960.
[24] Taga T. Analysis of mean effective gain of mobile antennas in landmobile radio environments [C]. IEEE Transactions on Vehicular Technology,1990,39(2),117-123.
[25]巫正中. RF-MEMS天线理论、建模仿真及特性研究[D].2002,重庆大学博士学位论文.
[26]杨雪松.微带可重构天线研究[D].2006,电子科技大学博士学位论