24G 陶瓷天线设计与PCB注意事项
2.4GHzPCB天线
2.4GHZ 2.4GHZ倒F及弯曲线 及弯曲线PCB蓝牙 PCB蓝牙天线 蓝牙天线设计指导 设计指导1Contents1 2 3 4 5 6 7 8 9 Introduction .................................................................................................................................................... 3 Inverted-F Antenna ........................................................................................................................................ 4 Meander Line Antenna................................................................................................................................... 5 Real Designs .................................................................................................................................................. 6 Proximity to Metal Objects ............................................................................................................................ 7 Proximity to Dielectric Materials................................................................................................................... 8 Network Analyser........................................................................................................................................... 9 Final Tuning.................................................................................................................................................. 10 Conclusion ................................................................................................................................................... 12Terms and Definitions ........................................................................................................................................ 13 Document History ............................................................................................................................................... 14List of Figures Figure 2.1: Inv erted-F Antenna ............................................................................................................................... 4 Figure 3.1: Meander Line Antenna .......................................................................................................................... 5 Figure 3.2: Input Impedance of Two Meander Line Antennas................................................................................. 5 Figure 4.1: Approximate Dimensions of Inverted-F Antenna................................................................................... 6 Figure 4.2: Approximate Dimensions of Meander Line Antenna ............................................................................. 6 Figure 7.1: Preparation Before Measurement ......................................................................................................... 9 Figure 7.2: Assembled System Ready to Measure ................................................................................................. 9 Figure 8.1: Locating Product in Far Field of Antenna............................................................................................ 10 Figure 8.2: Final Tuning Procedure....................................................................................................................... 11第 2 页 共 13 页1IntroductionThis document outlines two ty pes of Printed Circuit Board (PCB) antennas used by CSR, which can be used with 2.4GHz radios. ■ Inverted-F ■ Meander Line In addition, this document discusses the effect of placing metallic or dielectric materials near an antenna.第 3 页 共 13 页2Inverted-F AntennaQuarterwaveInput OutputFigure 2.1: Inverted-F Antenna The inv erted-F is a quarterwav e antenna. It is bent into an L-shape. The shorter side is connected to earth. The longer side is left open-circuit at the end. The f eed point is located somewhere between the earth end and the open end. The resulting structure resembles the letter F and possesses the properties of both a loop antenna due to the circulating current from the f eed point to ground and a whip antenna due to the open circuited straight section. In the PCB v ersion, the antenna is printed on the top layer and a ground plane is placed near the antenna on the top lay er. There must not be a ground plane underneath the antenna. The aim is to make the quarterwav e section resonate at the midband frequency (which is 2441MHz f or 2.4GHz ISM radios). The f eed point (which is the input/output connection) is connected to the L-Shape at the point corresponding to 50∧ . Experiment with measurement to determine the correct location for the feed point and length of this antenna.第 4 页 共 13 页3Meander Line AntennaS Ground Plane Input Output第 5 页 共 13 页Figure 3.1: Meander Line Antenna The length of the meander line antenna is difficult to predict. It is usually a bit longer than a quarterwav e but dependent on its exact geometry and proximity to the ground plane.Note:In Figure 3.1 the ground plane is shown in black. S is the distance from the ground plane. See Figure 4.2 for approximate dimensions. This ty pe of antenna is alway s a PCB version. The antenna is printed on the top lay er and a ground plane is placed near the antenna on the top lay er. There must be no ground plane underneath the radiating section of the antenna.Smith ChartABFigure 3.2: Input Impedance of Two Meander Line Antennas The real part of the impedance of this antenna is about 15∧ to 25∧ , depending on geometry and proximity to the ground plane. The impedance matching is done by adjusting the length of the antenna until the input impedance is at the unity conductance circle (when normalised to 50∧ ), in the top half of the Smith chart (Point A). A shunt capacitor is then connected between the antenna input and ground to match to 50∧ (Point B). Experimental measurement is used to determine the correct design.4Real Designs18.0mm13.5mm Width=0.8mm 6 .0mm 5 .0mm Not to scaleGround PlaneActual SizeFigure 4.1: Approximate Dimensions of Inverted-F Antenna第 6 页 共 13 页1.5mm1.0mm4.4mm Width=0.5mm 2.8mm 1.7mm Ground Plane Not to scale1.5pF CapacitorPlaced immediatel y after F eedpoint8 .0 mm FeedpointActual SizeFigure 4.2: Approximate Dimensions of Meander Line Antenna第 7 页 共 13 页5Proximity to Metal ObjectsCSR recommends keeping metal objects as far away f rom the antenna as possible. Keeping metallic objects out of the near field is usually adequate. Near Field = 2D / λ D is the largest dimension of the antenna. In the case of these antennas, this is approximately a quarterwav e (λ/4).Notes:2λ is the wav elength of the signal in f reespace. In the 2.4GHz ISM band, λ=122mm in freespace. Substituting D=λ/4 into the Near Field equation giv es Near Field = λ/8. Near Field = 122/8 mm = 15.25mm.第 8 页 共 13 页6Proximity to Dielectric MaterialsDielectric materials (like plastic or FR-4) detune an antenna by lowering its resonant frequency. The effect is not as serious as placing an antenna next to metal objects and can be corrected by reducing the length of the antenna. Theref ore, it is important to tune the antenna when it is in the product. This is done during the dev elopment of the product.第 9 页 共 13 页71. 2.Network AnalyserCut the PCB track (trace) just before the antenna matching network to isolate the f ilter and previous stages f rom the measurement. Connect a coaxial cable between the VNA and the PCB of the product. The coaxial cable must hav e f errite beads fitted over its outer sleeve. The f errite beads help to prev ent RF currents from f lowing on the outer sleeve, which would disturb the measurement. Solder the outer sleeve of the coaxial cable to the ground plane of the PCB as close as possible to the input of the antenna-matching network. Perf orm a One-Port calibration on the VNA with Open, Short, Loads connected at the end of the coaxial cable inside the product. Solder the inner conductor of the coaxial cable to the input of the antenna-matching network. Tune the antenna by adjusting the values of any “matching network” components, the feed point of the antenna or the length of the antenna until the S11 trace (display ed on the VNA) is at the centre of the Smith chart at the midband f requency 2441MHz. Repair the cut track by putting a small amount of solder over the cut.Use a v ector network analyser (VNA) to perform the initial tuning of the antenna:3. 4. 5.6.Figure 7.1: Preparation Before MeasurementVNAFerrite BeadsAntenna 2.4GHz RadioFigure 7.2: Assembled System Ready to Measure第 10 页 共 13 页8Final TuningAfter tuning the antenna using the VNA procedure, it is necessary to perf orm fine-tuning. This y ields a small improv ement and is the f inal optimisation of the antenna. It is best to perf orm this procedure in an anechoic chamber, but when this is not possible, an indoor or outdoor test range can be used. It is important to minimise radio signal reflections. Avoid metallic objects such as lab-benches, filing cabinets, lampposts and cars.Approximately 2m RX Antenna2.4GHz RadioSpectrum Analy serFigure 8.1: Locating Product in Far Field of Antenna第 11 页 共 13 页Connect omni directional receive antenna to a spectrum analyser Place fully assembled product approximatel y 2m away from receive antenna Put product into continuous transmitWatch power level of received signal on the specturm anal yser while moving receive antenna ±10cm in each of x,y,z planes to ensure it is not located in a null point. A sudden dip in received power indicates a null pointYesIs antenna located in a null point?No Rotate product around in the x,y,z planes until the maximum power level is observed on the spectrum anal yser. This ensures that the dominant polarisation mode of the antenna is measured.NoHas the maximum possible power level been observed on the spectrum anal yser?Yes Record power level observed on the spectrum analyser. Turn off product, disassemble it and make adjustments to length of antenna, feed point or matching componentsReassemble product and place it in the same location and orientation as beforeNoHas the maximum receive power been obtained?Yes End of procedure Repeat process on multiple devices to ensure results are repeatableFigure 8.2: Final Tuning Procedure第 12 页 共 13 页9ConclusionMetal objects should be kept at least 15.25mm away from the Inverted-F and Meander Line types of antennas in the 2.4GHz ISM band f or the antenna to work efficiently. If that is not possible, experiment to determine an acceptable trade-off between antenna performance and product size. Ev en by f ollowing these rules, antenna detuning can occur. This usually results in lowering the resonant frequency of the antenna. Correct this by reducing the length of the antennaTerms and DefinitionsISM PCB RF VNA Industrial, Scientific and Medical Printed Circuit Board Radio Frequency Vector Network Analyser第 13 页 共 13 页。
pcb布板时应注意的事项和总结
pcb布板时应注意的事项及总结作为PCB工程师，在Lay PCB，应重点注意那些事项？1、电源进来之后，先到滤波电容，从滤波电容出来之后，才送给后面的设备。
因为PCB上面的走线，不是理想的导线，存在着电阻以及分布电感，如果从滤波电容前面取电，纹波就会比较大，滤波效果就不好了。
2、线条有讲究：有条件做宽的线决不做细，不得有尖锐的倒角，拐弯也不得采用直角。
地线应尽量宽，最好使用大面积敷铜，这对接地点问题有相当大的改善。
3、电容是为开关器件(门电路)或其它需要滤波/退耦的部件而设置的，布置这些电容就应尽量靠近这些元部件，离得太远就没有作用了。
4.Y 电容通用脚距10mm，留出焊盘，中间空隙是8mm，中间最好不要走线，中间不走线，放置的地方当然是板子的上下，左为强电，右为弱电。
强电端的GND最好为功率地，右边的弱电最好是靠近变压器的GND引脚。
5.再往大功率的，遵循的是两点：（1）主回路最好不要使用跳线，若一定要用就需加套管，跳线的上面若有元器件的话，还需点胶。
（2）在有限的平面积里及安全间距内尽可能的加粗，若不能加粗，就需要加铺焊层。
Lay PCB（电源板）时，结合安规要求，重点注意那些事项？1、交流电源进线，保险丝之前两线最小安全距离不小于6MM，两线与机壳或机内接地最小安全距离不小于8MM。
2、保险丝后的走线要求：零、火线最小爬电距离不小于3MM。
3、高压区与低压区的最小爬电距离不小于8MM，不足8MM 或等于8MM的。
须开2MM的安全槽。
4、高压区须有高压示警标识的丝印，即有感叹号在内的三角形符号；高压区须用丝印框住，框条丝印须不小于3MM5、高压整流滤波的正负之间的最小安全距离不小于2MM6.按照先大后小，先难后易的原则，即重要的单元电路，核心元件应当优先布局。
7.布局应参考原理图，根据主板的主信号流向规律安排主要元器件。
8.布局尽量满足总的连线尽可能短，关键信号线最短，高电压，大电流信号与小电流，低电压的弱信号完全分开，模拟信号与数字信号分开，高频和低频信号分开，高频元器件间隔要充分。
蓝牙耳机陶瓷天线摆放注意事项
PCB大小: 33mm x7mm 空区大小: 5.5mm x 4.5mm
调频用元件
推荐使用π型匹配，调试天线的阻抗和频率
1：天线摆放注意事项(单极天线)
天线的頂部、底部、前方都净空区，不能有金属，这样天线的辐射 效率和损耗才能达到最佳的效果。
顶部方向(A)
(A)
底部方向(B)
前方(C)
陶瓷天线
(C) M
(B)
1：陶瓷天线应该放在线路板的边缘，并在板边角落位置。 2：有较大的金属元件需要放在天线的周围时候，金属元件离天线 的的距离至少保存3mm以上，包括USB充点口 铜柱 麦克风 电池
2：天线摆放注意事項(双极
Side Vie w
箭頭向外方向 禁止任何金属
1：有较大的金属需要摆放在天线周围时（按键或者咪头）尽量不要进入到净空区里面，离天线的距离保持在 3mm以上，上下的距离保持在3-5mm以上，包括充电铜柱，触摸铜箔，电池，金属饰物。 2：双极天线建议使用在长条的板子，或者水滴形板子上，摆放的位置越接近中间越好，有些看实际的板框来 确定天线的具体走向和设计，天线尽量在中间，天线两侧的地比较完整，天线的效果相对来说会比较好，不容 易出现死角。
以下图来看当入耳式蓝芽耳机以这种方式配戴时， 天线于PCB上的位置选择有以下两种较佳。
B位置优于A位置，以上图中的红色线为地，天线到地的距离2-2.5mm左右，线宽可以根据匹配料焊盘的宽度来 确定走线的大小。
若是是共板设计的，天线的摆放在中间，左右对称出现，因为现在的耳机多采有不分主从设计，故两边的耳机 天线的需要匹配。两边的天线的尽量采取大颗的天线，尽量远离人体，天线可以有效的辐射。
PCB全向天线 2.4G
首 页新闻资讯技术资料论 坛网电子元器件搜索：IC库存(8958万) PDF资料(329万) IC价格 IC求购 资讯维库电子市场网是国内外知名的电子元器件交易网站，为电子行业的广大用一种水平极化平面印刷全向天线的设计新闻出处：广东电子商贸网 发布时间： 2007-11-20来源：电子技术应用 作者：西安电子科技大学 高红卫 焦永昌 张福顺摘 要：介绍了一种水平极化奎向天线，先仿真设计再加工制作，最后实际测试。
结果表明：在2．4GHz频段上，获得了120MHz的带宽(VSWR<3)和良好的全向方向图。
该天线被印刷在一块面积只有24.3×24.3mm2的FR-4介质板上，结构简单凑，可用于无线局域网终端通信。
关键词：水平极化全向天线2．4GHz频度无线局域网终端全向天线在无线通信中发挥着重要的作用，常见的多是垂直极化天线，水平极化的不多，然而水平极化全向天线却有着特的应用。
在城市或者室内无线环境中，虽然基站发射的都是特定的极化信号，比如常见的垂直极化信号，但是很难直传播到移动终端，一般要经过多径传播，即信号要经过反射或者绕射，或者反射加绕射，或者绕射加反射，才能到达移终端。
在经过多径传播后，极化要发生旋转，因此一般来说，多径信号到达移动终端时，既有水平极化信号，又有垂直化信号。
由于多径传播是随机的，因此这些信号也是随机的。
可以考虑在移动终端安装一个水平极化天线和一个垂直极天线，从而获得较好的接收信号。
或者在发射端和接收端分别安装两个天线，一个水平极化天线和一个垂直极化天线，得到两个不相关的信号，这就是极化分集，它正是利用了空中水平路径和垂直路径的不相关性来实现抗快衰落的。
据研究，发射端和接收端都采用水平极化天线的系统比发射端和接收端都采用垂直极化天线的系统可以多获得平均10dB的功率。
因此研究水平极化全向天线有着重要的现实意义。
本文设计了一种可用于2．4GHz频段移动终端的水平极化全向天线，属平面结构，被印刷在一块面积只有24．3×24．3的常见电路板上(FR-4)。
干货·各种小天线的PCB设计要点
干货·各种小天线的PCB设计要点天线是各种智能设备都需要的重要部件，所有需要用到无线的设备都需要用到它。
现在是无线时代，网络路由器都是无线WIFI，电脑，手机连网络再也不用网线连接了，还有蓝牙耳机，蓝牙鼠标，蓝牙键盘等等不再有电线了，这个天线的性能就至关重要了。
一般天线的选择有一些因素，除了考虑性能还要考虑成本，所以在选择天线的时候，需要综合考虑。
今天上尉Shonway就给大家讲讲各种天线的设计及设计要点。
第一种、PCB板载天线这种天线成本低，但性能会稍微差一点。
PCB板载天线也有几种形式。
a,平面倒F型天线，英文缩写即PIFA如下图所示就是倒F的PCB板载天线图1图2下面这个是上面平面倒F的PCB板载天线的变种，由于空间不够，扭曲一下。
此倒F天线PCB设计都有哪些需要注意的问题？我们首先要知道这个射频知识，Shonway以前出过一篇文章，对于射频，任何铜箔，导线都不能看成是简单的导线，他是由很多阻容电路组成的一种等效电路，你看到短路的，对于射频就不是短路。
以这个思路我们看看这个倒F天线的PCB设计。
如下图所示图3这里有六点要注意1、这个倒F天线，不是随便画的，网上有专门的这种天线的库，拿过来，按要求放上去就好。
如果空间不够，那就是自己通过仿真自己制作了自己专用的天线了。
原创今日头条：卧龙会IT技术2、RF馈点这里引出来的线阻抗必须做到50ohm3、接地馈点必须接地牢靠4、地平面必须要多打地过孔，如上图所示，这个过孔间距多少合适的话，我们以前一篇卧龙会布布熊老师写过一篇文章，大家找一下可以看看5、天线这里所有层铜箔必须净空。
6、天线必须放在PCB板的角落里，最好三面都是空的，如图2所示，上面三面都是空的手机上的天线叫平面倒F天线，原理上是用一个平面接上一个接地平面馈点，与RF馈点组成，如下图4所示图4上面图4从左下方RF馈点这个箭头看过去，就是一个倒F。
同样是倒F结构，但手机中的天线采用的是平面结构，这个倒F天线就比PCB板载天线性能就会好很多，这样空间又比较少，成本又低，对于手机天线是最好的选择。
自己动手制作路由器2.4G定向天线
自己动手制作路由器2.4G定向天线2012-04-04 00:05本站整理Emmanuel字号：A+|A-2.4GHZ本身就是高频要求制作精度高，如果您动手能力差的话还是不要做的好许多网友看到网上的制作资料就急不可耐的去找材料，然后加班加点的制作。
等做出了天线发现效果不怎么样，或出了这样和那样的问题，才肯坐下来继续研究资料。
其实你大可研究好了再做，网上的图纸各种各样，你知道它的材料吗？因为它来自世界各地。
缩短率，平衡-不平衡转换，原理，构造，阻抗匹配等。
最起码得先了解些原理吧，比如有个网友做了个双菱形的感觉效果不怎么好就想再做个4菱形的，尺寸和原来的一样结果做出来了增益没有高，减益倒高了不少，因为双菱形的阻抗和4菱形的根本不一样。
无线系统的天线长度通常是使用频率波长的1/4，2.4Ghz由于频率高，波长当然就短，所以天线自然就特别短，因此使用 2.4Ghz系统当然就再不需要传统那样长长的拉杆天线了。
单一菱形四条边：每一边长 1/4 波长，单个菱形全长 1个波长，有些人会计入缩短系数(根据线径粗细0.96-1.05)，所以有这么多值跑出来，最好自己计算。
频率为2.4GHZ的波长是12.5cm ，2.4G波长=3*108/2.4？….*109=0.125m=12.5cm，根据频点可得不同长度。
如2.45G频率的波长12.24厘米，1.5mm铜丝的缩短系数0.96，则边长=波长*缩短系数/4=29.39毫米反射板的宽度应大于12.5CM，取140MM也是合理的，但不要太大了，能有个弧度最好为了减少杂波干扰,前面还可以制作一个挡板，过滤掉波长为几十毫米以下的杂波，当然这个工艺性要求较高，省去也是可以的。
引下线可以采用50欧姆的同轴电缆，长度计算应与阻抗相匹配。
2.4G高频信号衰减厉害，馈线最好不要超1米。
反射板屏蔽掉能获得更大增益，双棱增益10DB，屏蔽12DB ;四棱增益13DB，屏蔽 14DB一个菱形标准是 3.15dbi，加反射板多 3db，菱形每多一倍加 3db，所以双菱形是 3.15+3+3=9.15dbi; 四菱形 12.15dbi;八菱形 15.15dbi; 16 菱形 18.15dbi;32 菱形21.15dbi;64 菱形 24.15dbi;128 菱形是 27.15dbi;要达到30dbi增益需要256 个菱形!!!高增益天线应用在短距离时，其效果并不见得会比低增益天线来的好(近距离时，低增益天线的"等效截面积"，有时会比高增益天线来的大)，如果再加上于室内使用，因为多重路径的关系，高增益天线的效果也不一定会比低增益天线好下面是国外网站10db定向天线制作过程：。
自制24G WIFI天线
自制2.4G WIFI天线以前我总觉得DIY天线是一件十分困难的事情，受到BG7IOO的影响，我现在对天线也发烧了。
由于收到自身技术和器材限制，我一般只玩手持机的天线，平时也经常跟BG7IOO通长途聊天线，权当生活中的一种乐趣！最近我沉迷于2.4G频段的WIFI，WIFI让人着迷之处在于它是有线宽带网络的无线延伸！但由于技术规范的限制，WIFI设备的发射功率都非常低，一般都是mW级的功率。
这样一来，数据传输的距离就显得捉襟见肘。
有鉴于此，很多业余无线电爱好者都热衷于在WIFI天线上做文章。
为了让自己的WIFI设备也能插上翅膀，我下定决心DIY一根属于自己的WIFI ANT！第1步：选型先上网收集天线资料，看到很多国外的天线DIYER做出来的WIFI天线真是五花八门！有螺旋天线、有八木天线、有菱形天线、有栅网天线、还有罐头天线......让人看得眼花缭乱。
经过再三筛选，最终把制作目标锁定在罐头天线上。
选择它为DIY对象主要是因为这种天线取材方便、效率高！十分适合初学者制作。
同时在05年的《业余无线电家》会刊第4期也有介绍。
不过，我喜欢把它的名字称为“圆筒天线”！第2步：制作圆筒天线之所以取材方便，是由于人人家里必定有铁罐、金属筒之类的东西。
我就是随便拿了一个奶粉罐制作的。
下面是我参照外国网站的图片而画的制作图。
各数据如下：中心频点＝2.445G圆筒直径＝127mm圆筒长度＝111mm振子长度＝31mm振子距圆筒底部边距＝37mm从图片可以看出，馈线的屏蔽网连接金属圆筒，信号通过圆筒反射到振子上，当然振子就是馈线的芯线了，芯线与金属筒是绝缘的，这点必须注意！在参照外国爱好者制作WIFI天线的同时，我加入了自己的想法：很多爱好者都喜欢在圆筒加装N座或BNC座，然后在馈线的连接处做对应的N头或BNC头，用于连接。
但我觉得虽然该方法对使用十分方便，但同时也对信号造成了损耗（估计1－2DBI），尤其在2.4G 的频段更加明显！因此，我决定把屏蔽网直接焊在圆筒上（焊接前先把外壳打磨光滑），而作为振子的芯线则保留其原来的泡沫绝缘。
WiFi天线对PCB布局布线和结构的要求详解-全文
WiFi天线对PCB布局布线和结构的要求详解-全⽂ 随着市场竞争的加剧，硬件设备正以集成化的⽅向发展。
天线也由外置进化内置再进化到嵌⼊式，我们先来介绍这类应⽤的天线种类： ⑴ On Board板载式：采⽤PCB蚀刻⼀体成型，性能受限，极低成本，应⽤于蓝⽛、WIFI模组集成； ⑵ SMT贴装式：材质有陶瓷、⾦属⽚、PCB，性能成本适中，适⽤于⼤批量的嵌⼊式射频模组； ⑶ IPX外接式：使⽤PCB或FPC+Cable的组合，性能优秀，成本适中，⼴泛应⽤于OTT、终端设备； ⑷ External外置类：塑胶棒状天线，⾼性能，独⽴性，成本⾼，应⽤于终端设备，⽆须考虑EMC等问题； 外置天线⼤家都很熟知了，我们直接看看三类内置天线需要的空间： 再来总结⼀下空间要求和性能指标： 以上就是WIFI2.4G的天线设计参考啦！ 天线最终的⽬的是要将射频信号辐射到⾃由空间，这时天线的设计就显得⾮常重要，但是天线设计很⼤程度上依赖于所安装平台的特性，另外天线对周围环境很敏感，这些原因导致很多情况下，天线对每个平台都是独⼀⽆⼆的设计。
由于客户对天线设计所考虑的因素不太清楚，这⾥给出⼀些我们对便携设备天线设计的⼀些建议，便于客户更好的设计⾃⼰的电路和PCB，增加项⽬成功的机会。
但是每个项⽬都有各⾃的特点，所以还有⼀些问题需要具体问题具体分析。
WiFi天线对PCB布局布线和结构的要求 1.天线的形式及天线位置和馈点尺⼨的建议 内置天线经常采⽤的⼏种形式分别为，分为弹⽚形式和chip贴⽚天线和FPC天线。
贴⽚天线的形式是统⼀规格的，有固定的尺⼨，焊盘的位置和尺⼨根据具体规格的天线也是固定的。
另外根据特定型号的天线有相关的天线周围净空的要求和设备尺⼨的建议等设计指导意见。
如果采⽤弹⽚形式，我们建议客户采⽤PIFA天线作为WiFi天线的形式，根据我们的经验，PIFA天线成功率和性能都要好⼀些。
天线RF 馈电焊盘应采尺⼨为2&mes;3mm，焊盘含周边≥0.8mm的⾯积下PCB所有层⾯不布铜。
天线设计注意事项
天线设计注意事项⼿机天线设计注意事项总结⼀、主板1.布线在关联RF的布线时要注意转弯处运⽤45度⾓⾛线或圆弧处理，做好铺地隔离和⾛线的特性阻抗仿真。
同时RF地要合理设计，RF信号⾛线的参考地平⾯要找对，并保证RF信号⾛线时信号回流路径最短，并且RF信号线与地之间的相应层没有其它⾛线影响它。
PCB板和地的边缘要打“地墙”。
从RF模块引出的天线馈源微带线，为防⽌⾛线阻抗难以控制，减少损耗，不要布在PCB的中间层，设计在TOP⾯为宜，其参考层应该是完整地参考⾯。
并且在与屏蔽盒交叉处屏蔽盒要做开槽避让设计，以防短路和旁路耦合。
2.布板RF模块附近避免安置⼀些零散的⾮屏蔽元件，同时少开散热孔。
最忌讳长条形状孔槽。
天线投影区域内有完整的铺地，同时不要天线侧安排元器件，特别是含⾦属结构的元件，如喇叭、马达、摄像头基板等⾦属元件和低频驱动器件，要尽量接地。
它们对天线的电性性能有很⼤的负⾯影响.3.天线的空间辐射会被主板的⾦属元件（包括机壳上天线附近的⾦属成分装饰件）耦合吸收后产⽣⼀定量的⼆次辐射，频率与⾦属件的尺⼨关联。
会造成整机产⽣⼀定的杂散，整机杂散问题还与天线与RF模块之间的谐振匹配电路有关，如果谐振匹配电路的稳定性不好，很容易激发产⽣⾼次谐波的⼲扰。
因此要求此类元件有良好的接地，消除或降低⼆次辐射。
⼆、机壳的设计由于⼿机内置天线对其附近的介质⽐较敏感，因此，外壳的设计和天线性能有密切关系。
外壳的表⾯喷涂材料不能含有⾦属成分，壳体靠近天线的周围不要设计任何⾦属装饰件或电镀件。
若有需要，应采⽤⾮⾦属⼯艺实现。
机壳内侧的导电喷涂，应⽌于距天线20mm处。
对于纯⾦属的电池后盖，应距天线20mm以上。
如采⽤单极天线，⾯板禁⽤⾦属类壳体及环状⾦属装饰。
电池（含电连接座）与天线的距离应设计在5mm以上。
三、天线结构1）PIFA天线基本注意：1，天线空间⼀般要求预留空间：W（宽），L（长），H（⾼）其中W（15-25mm）、L（35-45mm）、H（6-8mm)。
2.4G天线设计完整指南（原理、设计、布局、性能、调试）
2.4G天线设计完整指南（原理、设计、布局、性能、调试）本文章使用简单的术语介绍了天线的设计情况，并推荐了两款经过测试的低成本PCB天线。
这些PCB天线能够与PRoC?和PSoC?系列中的低功耗蓝牙(BLE)解决方案配合使用。
为了使性能最佳，PRoC BLE和PSoC4 BLE2.4GHz射频必须与其天线正确匹配。
本应用笔记中最后部分介绍了如何在最终产品中调试天线。
1、简介天线是无线系统中的关键组件，它负责发送和接收来自空中的电磁辐射。
为低成本、消费广的应用设计天线，并将其集成到手提产品中是大多数原装设备制造商(OEM)正在面对的挑战。
终端客户从某个RF产品(如电量有限的硬币型电池)获得的无线射程主要取决于天线的设计、塑料外壳以及良好的PCB布局。
对于芯片和电源相同但布局和天线设计实践不同的系统，它们的RF(射频)范围变化超过50%也是正常的。
本应用笔记介绍了最佳实践、布局指南以及天线调试程序，并给出了使用给定电量所获取的最宽波段。
图1.典型的近距离无线系统设计优良的天线可以扩大无线产品的工作范围。
从无线模块发送的能量越大，在已给的数据包错误率(PER)以及接收器灵敏度固定的条件下，传输的距离也越大。
另外，天线还有其他不太明显的优点，例如：在某个给定的范围内，设计优良的天线能够发射更多的能量，从而可以提高错误容限化(由干扰或噪声引起的)。
同样，接收端良好的调试天线和Balun(平衡器)可以在极小的辐射条件下工作。
最佳天线可以降低PER，并提高通信质量。
PER越低，发生重新传输的次数也越少，从而可以节省电池电量。
2、天线原理天线一般指的是裸露在空间内的导体。
该导体的长度与信号波长成特定比例或整数倍时，它可作为天线使用。
因为提供给天线的电能被发射到空间内，所以该条件被称为“谐振”。
图2. 偶极天线基础如图2所示，导体的波长为λ/2，其中λ为电信号的波长。
信号发生器通过一根传输线(也称为天线馈电)在天线的中心点为其供电。
天线走线规则技巧及PCB制程培训讲座共35页文档
41、俯仰终宇宙，不乐复何如。 42、夏日长抱饥，寒夜无被眠。 43、不戚戚于贫贱，不汲汲于富贵。 44、欲言无予和，挥杯劝孤影。 45、盛年不重来，一日难再晨。及时 当勉励 ，岁月 不待人 。
21、要知道对好事的称颂过于夸大，也会招来人们的反感轻蔑和嫉妒。——培根 22、业精于勤，荒于嬉；行成于思，毁于随。——韩愈
23、一切节省，归根到底都归结为时间的节省。——马克思 24、意志命运往往背道而驰，决心到最后会全部推倒。——莎士比亚
25、学习是劳动，是充满思想的劳动。——乌申斯基
谢谢！
影响GPS天线性能的主要因素及其使用注意事项
影响GPS天线性能的主要因素及其使用注意事项我们知道，GPS 就是通过接受卫星信号，进行定位或者导航的终端(GPS是什么)。
而在这接受信号的过程中就必须用到天线，故我们将接受信号的天线称之为GPS天线。
GPS卫星信号分为L1和L2，频率分别为1575.42MHZ和1228MHZ，其中L1为开放的民用信号，信号为圆形极化(GPS原理)。
信号强度为166-DBM左右，属于比较弱的信号。
这些特点决定了要为GPS信号的接受准备专门的天线。
下面小编就为大家介绍有关GPS天线性能与使用注意事项的知识(GPS定位)。
影响GPS天线性能的主要是以下几个方面1、陶瓷片：陶瓷粉末的好坏以及烧结工艺直接影响它的性能。
现市面使用的陶瓷片主要是25×25、18×18、15×15、12×12。
陶瓷片面积越大，介电常数越大，其共振频率越高，接受效果越好。
陶瓷片大多是正方形设计，是为了保证在XY方向上共振基本一致，从而达到均匀收星的效果。
2、银层：陶瓷天线表面银层可以影响天线共振频率。
理想的GPS陶瓷片频点准确落在1575.42MHz，但天线频点非常容易受到周边环境影响，特别是装配在整机内，必须通过调整银面涂层外形，来调节频点重新保持在1575.42MHz。
因此GPS整机厂家在采购天线时一定要配合天线厂家，提供整机样品进行测试。
3、馈点：陶瓷天线通过馈点收集共振信号并发送至后端。
由于天线阻抗匹配的原因，馈点一般不是在天线的正中央，而是在XY方向上做微小调整。
这样的阻抗匹配方法简单而且没有增加成本。
仅在单轴方向上移动称为单偏天线，在两轴均做移动称为双偏。
4、放大电路：承载陶瓷天线的PCB形状及面积。
由于GPS有触地反弹的特性，当背景是7cm×7cm无间断大地时，patch天线的效能可以发挥到极致。
虽然受外观结构等因素制约，但尽量保持相当的面积且形状均匀。
放大电路增益的选择必须配合后端LNA增益。
24G+PCB天线设计
Freescale Semiconductor AN2731 Rev. 1.2 11/2004Application NoteCompact Integrated AntennasDesigns and Applications for the MC13191/92/931 Introduction Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 1Good antenna design is the most critical factor in 2 Antenna Terms . . . . . . . . . . . . . . . . . . . . . . . . 2obtaining good range and stable throughput in a wireless 3 Basic Antenna Theory . . . . . . . . . . . . . . . . . .2application. This is especially true in low power and 4 ImpedanceMatching . . . . . . . . . . . . . . . . . . . 6compact designs where antenna space is less than 5 Miniaturization Trade-offs . . . . . . . . . . . . . . 13optimal. However several compact cost efficient and 6 Potential Issues . . . . . . . . . . . . . . . . . . . . . . 14very effective options exist for implementing integrated 7 Recommended Antenna Designs . . . . . . . . 14 8 Design Examples . . . . . . . . . . . . . . . . . . . . . 16antennas.To obtain the desired performance it is required thatusers have at least a basic knowledge about howantennas function and the design parameters involved.These parameters include selecting the correct antennaantenna tuning matching gain/loss and knowing therequired radiation pattern.This note will help users understand antenna basics andaid in selecting the right antenna solution for theirapplication. Freescale Semiconductor Inc. 2004. All rights reserved.Antenna Terms2 Antenna TermsAntenna Gain A measure of how well the antenna radiates the RF power in a given direction compared to a reference antenna such as a dipole or an isotropic radiator. The gain is usually measured in dB’s. A negative number means that the antenna in question radiates less than the reference antenna a positive number means that the antenna radiates more.Decibel dB A logarithmic scale used to represent power gain or loss in an RF circuit. 3 dB is a doubling of the power -3 dB is half the power. -6 dB represents half the voltage or current and quarter the power.Radiation Resistance The part of antenna’s impedance which produces radiated power. The measured impedance of an antenna is comprised of radiation resistance and loss.3 Basic Antenna TheoryEvery structure carrying RF current generates an electromagnetic field and can radiate RF power to someextent and likewise an external RF field can introduce currents in the structure. This means thattheoretically any metallic structure can be used as an antenna. However some structures are more efficientin radiating and receiving RF power than others. The following set of examples explains this concept.Transmission lines striplines coaxial lines etc. are designed to transport RF power with as little radiationloss as possible because these structures are designed to contain the electromagnetic fields. To obtain anyappreciable radiation from such a structure requires excessively high RF currents which causes lowefficiency due to high losses. Likewise the ability to introduce RF currents into the structure is ofimportance described by the feed point impedance. If the feed point impedance is very high lowand/orhighly complex it is difficult to introduce RF current with good efficiency.The antenna structure should be of reasonable size compared to the wavelength of the RF field. A naturalsize is half a wavelength which corresponds to approximately 6 cm at the 2.4 GHz ISM band. This size iseffective because when fed with RF power at the center point the structure is resonant at the half wavefrequency. Reducing the size below 6cm tends to make the antenna less visible to the RF field and notresonant which causes low efficiency. Not all structures make an efficient antenna.Numerous structures have been devised that provide good efficiency and impedance match but most ofthese are derived from a few basic structures. A short description of these basic antennas and some goodadvice on how to implement these with success is provided later in this note.Thisnote does not include complicated formulas concerning antenna theory because it is beyond the scopeof this note. The intention of this note is to provide basic information about how antennas work whichshould allow users to achieve reasonable performance with a minimum number of attempts.If users are interested in performing comp lex calculations and antenna simulations they should consult theabundant and widely available literature concerning antenna theory and design. Note that simply copyingan existing design does not necessarily ensure reasonable performance. A lot of external factors affectantenna tuning gain radiation patterns etc. An antenna tuned for one set of environmental factors maynot perform at all if put into a new environment and may require a lot of tuning to achieve even reasonableperformance. Compact Integrated Antennas Rev. 1.22 Freescale Semiconductor Basic Antenna Theory3.1 Basic Antenna Variations3.1.1 3.1.1 Dipole AntennaThe dipole is one of the most basic antennas. The dipole is a straight piece of wire cut in the center and fedwith a balanced generator or transmission line. As previously stated this structure is resonant ornon-reactive at the frequency where the conductor length is 1/2 wavelength. For the ISM band this lengthis approximately 6 cm or about 2 inches. At this length the dipole shows resonance the feed impedanceis resistive and is close to 73 Ohms. This also holds true for a very thin wire in free space. Total Length is Approximately Wavelength At 2.4 GHz Length is Approximately 6 cm Figure 1. Basic DipoleA practical dipole of some thickness loaded with different dielectric materials PCB etc. and perhapsrelatively close to ground shows resonance at a slightly shorter length than calculated and the radiationresistance drops somewhat. For dipoles not too close to ground the shorting factor is typically in the rangeof 5-20 the shorter being more heavily dielectric loaded and radiation resistance is in the range of 35-65Ohms.This dipole setup exhibits a relatively good match to a 50 Ohm generator but the feed is differential. Asmall ceramic balun can be used forsingle-ended feed. The bandwidth is typically 2-5 depending on thereturn loss required. The radiation pattern in free space is doughnut-shaped with pronounced dips alongthe direction of the wires.To fill out these dips the outer ends of the antenna can be bent at a 45 degreeangle. Several configurations are possible including the “broken arrow” shape. Any materials close to theantenna can distort the radiation pattern. Compact Integrated Antennas Rev. 1.2Freescale Semiconductor 3Basic Antenna Theory Figure 2. Dipole Shapes to Improve Omnidirectional CharacteristicsTo reduce the size of the dipole several options exist: Replacing some of the wire length with loading coils Bending the dipole ends back on the dipole Folding the dipole into a meander pattern Hairpin or coil loading of the center Capacitive loading of the dipole ends Compact Integrated Antennas Rev. 1.24 Freescale Semiconductor Basic Antenna Theory Folding Inductive Loading Meander Pattern Hairpin Loading Figure 3. Dipole Loading ExamplesIn general the smaller the antenna the lower the radiation resistance and the lower the efficiency. Theantenna should also be removed somewhat from the ground plane preferably at least wavelength 3 cmbut not less than 1 cm. Sometimes a loading technique is employed where the dipole ends are bent close to theground plane or even loaded with small capacitors to ground. This technique shorts the dipole considerably butcauses heavy RF currents to flow in the ground plane resulting in low efficiency. Often some of the other loadingtechniques result in better performance. Compact Integrated Antennas Rev.1.2Freescale Semiconductor 5Impedance Matching4 Impedance MatchingFor heavily loaded antennas and antennas close to ground the radiation resistance maydeviateconsiderably from 50 Ohms which causes a poor match. An Inductive/Capacitive LC matching networkmay be employed but better efficiency is possible by raising the feed impedance.These techniques may also be employed if an impedance higher than 50 Ohm is required.The current and voltage distribution on a dipole is such that the impedance is low in the center and raisestowards the ends. By tapering the dipole at some distance from the center an appropriate match can befound. The tapering may take the form of Gamma Delta or Capacitive tapping as shown in Figure 4. Thisallows for matching impedances from 2 up to 300 Ohms. Some loading may be required to take out thereactance introduced by the tapering or the antenna could be slightly offset tuned to compensate for theadded reactive component. Gamma Impedance Match Delta Impedance Match Capacitive Impedance Match Figure 4. Impedance MatchingAnother approach is using the folded dipole. This is where two parallel wires are placed closely together.Due to the tight coupling the current distribution is approximately proportional to the surface area of eachwire. This means that in two equal wires the current in the feeding wire is approximately half the value ofthe wires together. Half the current at the same power means twice the voltage or four times the impedanceof 73 Ohms 292 Ohms. In practice the impedance is somewhat lower as in the normal dipole case.however by changing the relative wire diameter or even introducing several wires it is possible to tunethe impedance from less than 100 Ohms to several hundred Ohms. Compact Integrated Antennas Rev. 1.26 Freescale Semiconductor Impedance Matching Figure 5. The Folded DipoleAll the different dipole types loading techniques and feeding networks total up to an enormous amountof possible combinations each with its own advantages and disadvantages. Selection of the correct designfor your application is best found using case-by-case assessment.4.1 Monopole AntennasIf one part of a dipole antenna is removed and replaced by an infinite ground plane the remaining half ofthe dipole “mirrors” itself in the ground plane much in the same way that one sees their own reflection inwater.For all practical purposes the monopole behaves as a “half” dipole. That is it has the same doughnutshaped radiation pattern the radiation resistance is half that of the dipole 37 Ohm it can be bend and befolded like the dipole and the same loading and feeding techniques can be applied.However one very important difference remains in that the antenna feed point is not balanced but singleended. Because of this and because most RF circuits are of the unbalanced type this antenna type has beenimmensely popular and a lot of variations of the monopole theme exist most designed to match 50 Ohms. Figure 6. Monopole Above a Ground Plane Showing the 癕irror” AntennaIt is important to note that the “whip” is only half the antenna and that the remainder is made up of theground plane or counter weight as it is sometimes called. In a practical application the ground plane isoften made up of the remainder of the PCB ground and supply planes traces and components. Compact Integrated Antennas Rev. 1.2Freescale Semiconductor 7Impedance MatchingThe ground plane should be a reasonably sized area compared to the antenna and should be reasonablycontinuous. If a monopole is used on a very small PCB perhaps even with only a small area of copperefficiency suffers and the antenna is difficult to tune. Components and tracks introduce additional lossesand affect the feed point impedance.As for the dipole resonance is obtained at a length slightly shorter than one quarter wavelengthtypically5-15 shorter. Typical lengths are slightly more than an inch or two or 3 to 5 cm. The radiation resistanceis caused by bending the antenna and like the dipole the markeddip in the radiation pattern can beeliminated. By bending the antenna closer to ground the radiation resistance and efficiency drops so theantenna should not be placed too close to ground. Like the dipole the monopole can also be folded andbent around corners if board space requires this or it can be loaded with series coils.Of the many variations that exist the following sections highlight the most common.4.1.1 PCB Whip Quarter Wave Monopole or Quarter WaveIf board space allows a full-size quarter wave antenna is quite efficient and often provides a reasonable match toa 50 Ohm system. Slight folding or bending of the ends has negligible impact on performance.4.1.2 Open Stub Tilted WhipIf the monopole is bent and traced along the ground plane it will be more compact and the null in theradiation pattern is partly eliminated. The antenna should not bee too close to ground preferably not closerthan 1/10 wavelength 1 cm or efficiency suffers too much. At this close spacing the radiation resistanceis so low in the order of 10 Ohms that a matching network is usually needed. If the monopole is veryclose to ground it resembles a transmission line with little or no radiation at all.4.1.3 The F-AntennaThe F-antenna can be thought of as a tilted whip where impedance matching is done by tapping theantenna at the appropriate impedance point. Because this antenna is reasonably compact has anomnidirectional radiation pattern good efficiency and is very simple it is used extensively in applicationsincluding the mobile communications business. It should be noted that the currents in the ground leg arehigh and that a good sized ground plane is necessary to provide good efficiency. Figure 7. Tilted Whip and F - Antenna Note the Ground Plane Area Compact Integrated Antennas Rev. 1.28 .。
2.4G天线运用_v1.2
2.4G WIFI 天线运用要点天线可以有很多种，目前我们主要用了两种天线处理方式，板载的和通过同轴线连接的。
板载的有PCB天线，和陶瓷天线（chip antenna）.通过同轴线连接偶极子类天线种类很多，不讨论。
这三种天线只要是尺寸大小和成本上符合我们产品上的运用，都可以使用。
从性能及方便角度考虑推荐使用非板载天线，这样天线在应用时有更大的灵活性及更容易避免干扰；从成本考虑推荐板载PCB天线。
不管哪种天线都必须保证是50欧姆的阻抗，目前我们在我们平台上运用的射频模块都是需求50欧姆天线。
1．推荐的PCB天线。
“倒F型”PCB天线是常用2.4G天线，优点在于运用简单，节约成本，辐射方向性和辐射效率都是通过测试验证了的，阻抗是50o欧姆。
z严格按照以上尺寸做天线PCB封装，单位是mm，铜皮厚是1oz.z粉红色的十字是天线的馈点，F中蓝色的那段接WIFI模块中的GND. 绿色的区域是净空区，绿色区不应有任何的的信号走线和铺铜。
z必须注意F中蓝色的接地脚必须连接大片的连续的GND,而且是靠近WIFI模块（可以说是RF_GND）,因为倒F天线是单极天线，以地平面构成整个天线整体，如果此接地端的地面积太小或不连续，天线的馈点阻抗难以保证，整个天线难以谐振。
以下是关于接地点不正确的做法接地点选择太偏，接地面积不够。
z对天线空间的要求：倒F型天线要求放置在PCB的边缘，F的长边（下图红色箭头所指部分）边缘距离板边不超过0.4MM，F型长边所指向部分PCB不要有铜，如不能避免，要求距离有12MM以上。
在天线周围不能有金属的东西，带金属的原件要可靠接地。
外壳要求距离倒F天线正面6MM以上，电镀或金属壳部分要求12MM以上。
2.陶瓷天线陶瓷天线内部结构是一段螺旋走线，使用才陶瓷天线的优点是节约空间，很多的产品由于机构上的限制做不了以上PCB天线，陶瓷天线的缺点是插损大，天线效率不高（10%--50%），成本花费。
z使用陶瓷天线时一定要外加π型网络，并让天线供应商提供匹配网络，才能达到理想效果。