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三米法一般是指天线到被测物的距离而场地长度至少应为测试距离的两倍标准的场为9*6*6而也会有些实验室建成7*4*3也能满足要求根据不同的标准EUT的摆放会不一样按55013的标准应该放在桌子的中心按55022的标准应该放桌子的边缘开阔场定义时，场地长度应该是测量距离的2倍，加上转台到吸波材料留一定空间，一般都到了9米左右，宽度为测量距离的1.732倍，大概是6米，高度至少要满足天线能上下4米，加上吸波材料的空间，就到了5米多了见得多的就是966了，当然这个时候EUT尺寸还不能太大，转台直径一般在1．5米到2米的，总之结构直接影响NSA 的，布局是有讲究的还有：转台到天线的距离3m，都叫3米法暗室。
决定是否标准，就看3米法测试的范围，比如测试频段从30M-1GHz，30M 时的波长决定了正确测试到这个频点，天线需要在1-4m上下移动。
移动时有测试到的值大小成谷峰走势，天线周围至少1米以上空间，以免影响天线的性能，低频影响更大。
再根据暗室NSA校验的要求，暗室最小尺寸约在8.5*6*5.5左右，再小的暗室都是不标准的，无法模拟开阔场。
在各种暗室测试结果发生争议时，优先准确的原则：开阔场--30m法--10米法--5米法--3米法关于暗室的要求请查看ANSI C63.4-2001 和CISPR163米法半波暗室的布置是天线校准后的相位中心（一般为天线的中心）到转台的中心为3米，但根据不同的标准EUT 的摆放有所不同，按13的标准应该放在桌子的中心，按22的标准应该放桌子的边缘。
暗室的大小标准的是966的。
到了GB6113.1(CISPR16)标准看了下标准上只详细讲述了开阔场的要求,在15章节里但没并规定电波暗室的尺寸。
微波暗室设计要求说明
1、主要用途：模拟自由空间，主要用于天线远、近场测试、分1m 法、3m 法或10m 法。
根据具体使用要求还可定制各种非标暗室。
2、性能指标：
频率范围：30MHz ～18GHz
（一）吸波材料反射损耗：30MHz ～18GHz ≥15dB （吸波材料采用复合吸波
测试方法按GB12190-90 标准
微波暗室内景
（三）归一化场地衰减± 4dB ，场均匀性0～6dB ，多径损耗均匀性±0.25dB 内。
3、结构组成：
（一）屏蔽室：屏蔽室由屏蔽壳体、屏蔽门、通风波导窗及各类电源滤波器等组成。
根据用户要求，屏蔽壳体可采用焊接式或拼装式结构均可。
（二）吸波材料：
1、单层铁氧体片：工作频率范围30MHz ～1000MHz 。
2、锥形含碳海绵吸波材料：锥形含碳海绵吸波材料是由聚氨脂泡沫塑料在碳胶溶液中渗透而成，具有较好的阻燃特性。
（三）其它：主要有信号传输板、转台、天线、监控系统等。
EMC 3米法暗室和10米法暗室介绍在屏蔽室的天花板和四面墙贴上吸波材料，地面的吸波材料采用活动式铺设，即构成EMC实验室。
该EMC 暗室（实验室）为十米法半电波暗室，在30MHz至18GHz的频率范围内，在3米测试距离拥有2米静区，10米测试距离拥有3米或更大静区，该暗室满足FCC、CE和VCCI对十米法暗室的认证、测试要求。
一.用途：可对通讯设备、电子、电气设备进行电磁兼容（EMC）测试，即电磁干扰（EMI）和电磁敏感度（EMS）测试。
适用频率30MHz-18GHz可延至40GHz。
二.主要规格及性能1.屏蔽效能，满足EN 50147-1、GB12190-90。
技术参数如下：频率 屏蔽效能14 kHz ＞ 60 dB 磁场100 kHz ＞ 80 dB 磁场100 kHz ＞ 100 dB 电场1 MHz ＞ 100 dB 磁场1 MHz ＞ 100 dB 电场100 MHz ＞ 100 dB 电场1 GHz ＞ 100 dB平面波 10 GHz ＞ 100 dB微波 18 GHz ＞ 100 dB微波 100 MHz ＞ 100 dB电场 1 GHz ＞ 100 dB &nb2.按照ANSI C63.4-2003的步骤和规定在直径3米的圆柱体静区内所有位置从30MHz至1GHz进行归一化场衰减测试，按照10米法测量的归一化衰减(NSA)值与理论值偏差优于±4dB；1GHz至18GHz频率范围内使用传输损耗（TL）测试方法进行测试，仅在5GHz、10GHz和18GHz三点进行测试,归一化衰减(NSA)值与理论值偏差优于±4dB。
同时满足CISPR16、EN50147-2、CISPR22-1997、GB9254-1998、VCCI V-3/99.05标准对场衰减的要求。
3.按照IEC61000-4-3步骤和规定，符合EN61000-4-3:1996和GB/T 17626.3-1998的要求，在30MHz至1GHz进行场均匀度测试，标准场为转台之上0.8米-2.3米范围内1.5米x1.5米的垂直平面，按照3米测试距离要求16个测试点的75%即12点场均匀性在0-6dB之间；1GHz至18GHz的测试仅在5GHz、10 GHz 和18GHz三点以低于3v/m进行测试。
附件：3m法半/全电波暗室技术要求及配置1、基本要求★3m法半/全电波暗室可进行30MHz～18GHz频率范围内的EMC测试。
1.1、暗室须满足的标准要求ANSI C63.4-2003,U.S. FCC (Class B) parts 15 and 18,EN50147EN 55022IEC6100-4-3－2006GR-1089-CoreCISPR11，14，15，16，22 ，25CISPR publication 17GB 9254-1998NRL8093DIN4102 A1DIN4102 B2MIL-STD 220AMIL-STD 461MIL-STD 4621.2 尺寸要求★暗室屏蔽体外尺寸不小于： 9.0m(L)× 6m(W)×6 m(H)★控制室（屏蔽室）内净空尺寸不小于： 8m(L)×4.0m(W)×3.0m(H) ★功放室（屏蔽室）内净空尺寸不小于： 2.0m(L)×4.0m(W)×3.0m(H)，1.3 暗室的性能要求★场衰减：从30 MHz～18 GHz 按照ANSI C63.4-2003 的标准测试，实际的NSA 和理论的NSA相比优于± 3.5 dB ，符合美国. FCC Class B(3m)和国际标准。
★静区：在30MHz ～1GHz 频率范围内严格按照ANSI C63.4-2003标准进行测试，在3 米测试距离，有一个直径2 米的圆柱体静区。
在静区内进行归一化场衰减测试的NSA 值和理论的NSA 值相比优于±3.5dB★场地电压驻波比：从1GHz - 18 GHz 按照CISPR16-1-4 ED2 2006和CISPR/A/710 FDIS，直径2米，高2米的圆柱体静区，测试距离3m，两个高度，两个极化方向场地电压驻波比优于6dB。
★场均匀度：从26MHz～18GHz 的频率范围内16 个测试点中的12 个点的均匀性为0～＋6 dB，标准场为转台之上0.8m～2.3m 范围内1.5m× 1.5m 的垂直平面★背景噪声：暗室内空间环境的背景噪声（暗室内转台、天线升降塔、照明灯和电视监视器等设备开启状态）测试电平比在30MHz～1GHz的频率范围内的EN55022、GB9254 标准所规定B 级的限值的电平至少低20dB，1GHz～6GHz电平低于6dB。
3m法电波暗室方案英文Title: 3M Method Electromagnetic Dark Room SolutionIntroduction:The 3M Method, also known as the 'Magnetized, Metalized, and Meshed' method, is a highly effective solution for creating an electromagnetic dark room. An electromagnetic dark room is a controlled environment designed to eliminate external electromagnetic interference, enabling precise testing and measurement of electronic devices and equipment. This article will delve into the details of the 3M Method and its benefits.Magnetized:The first step in implementing the 3M Method is magnetization. This involves strategically placing magnets around the perimeter of the dark room. The magnets create a magnetic field that acts as a shield against external electromagnetic waves. By neutralizing the magnetic field, the 3M Method prevents any external electromagnetic interference from entering the dark room.Metalized:The second step of the 3M Method is metalization. The walls, ceiling, and floor of the dark room are coated with a layer of highly conductive metal, such as copper or aluminum. This metalized coating acts as a Faraday cage, enhancing the shielding capability of the dark room. The metal layer reflects and absorbs external electromagnetic waves, preventing them from penetrating the room and affecting the measurements or tests conducted inside.Meshed:The final step of the 3M Method is meshing. Fine mesh screens are installed on windows, doors, and ventilation systems of the dark room. These mesh screens act as additional barriers against electromagnetic waves, allowing the controlled environment of the dark room to remain undisturbed. The mesh screens are designed to have a specific mesh size that blocks the passage of electromagnetic waves while allowing air circulation and visibility.Benefits of the 3M Method:1. Enhanced Accuracy: By creating an electromagnetic dark room using the 3M Method, researchers, engineers, and scientists canachieve highly accurate test results and measurements. Eliminating external electromagnetic interference ensures that the data obtained is reliable and consistent.2. Confidentiality: The 3M Method provides an added layer of confidentiality by preventing any external interference that could compromise sensitive information or intellectual property. This makes it an ideal solution for research and development facilities or companies dealing with proprietary technologies.3. Compliance: Certain industries, such as aerospace, telecommunications, and healthcare, require strict compliance with electromagnetic compatibility regulations. The 3M Method ensures that the testing processes meet these standards, allowing companies to avoid costly penalties and legal issues.Conclusion:The 3M Method provides an effective solution for creating an electromagnetic dark room, enabling accurate and reliable testing and measurements of electronic devices and equipment. By magnetizing, metalizing, and meshing, the dark room becomesshielded from external electromagnetic waves, ensuring a controlled environment. The benefits of implementing the 3M Method include enhanced accuracy, confidentiality, and compliance with industry standards.。
技术文件3m法电波暗室辐射场抗扰度场地均匀性校准规程The method of uniform field strength calibration in 3mchamber第一版The 1st edition批准：日期：审定：日期：编制：日期：2009.05.20 QJ/63.740-20091 适用范围和目的Scope and object:IEC61000-4-3测试中的场地均匀性校准The calibration of field in IEC61000-4-32引用文件Normative referencesIEC 61000-4-3：1998电磁兼容试验和测量技术射频电磁场辐射抗扰度试验Testing and measurement techniques- Radiated, radio-frequency, electromagnetic field immunity test3校准使用的仪器设备：Test equipment:①3m法电波暗室Anechoic chamber②射频信号发生器RF signal generators:③宽频功放power amplifier④发射天线 field generating antennas⑤场强探头 field strength monitoring antenna⑥场强仪 field strength monitor⑦功率仪 power meter4 校准过程：a) 场强探头位置的确定Locate the field strength probe position确认IEC61000-4-3标准测试中所使用垂直均匀域平面，定出需要校准的16个点的位置； Locate the vertical uniform area and the 16 measuring point for calibration as following:Figure11111 12131421 22 23 2431 32 34 33 41 42 43 44测试中，场强探头应放置在如图1所示的16个点上，其中场强探头的垂直投影应分别落在图2所示的地面上的1、2、3、4点上，如图2;场强探头的高度应在图3所示的1、2、3、4位置：During the test, the field strength probe should be put in the 16 poison as shown in figure1,the vertical projection of the probe should located on position 1 to 4 on the ground as shown in figure 2, and the height of the probe should be at position 1 to 4 in figure 3.Figure22 34 14321 Figure 3b)吸波材料位置的确认Locate the absorber position在地面上铺设使用的吸波材料，记录吸波材料的配设位置, mark1至mark4分别为吸波材料铺设的4个角；Put additional absorber on the ground, and record the position of the 4 angle of the absorber as in figure 4:Mark 3Mark4 Mark 2Mark 1Figure 4c)将天线放置在距离垂直均匀域平面3m远的位置处Put the antenna on the point 3m away from uniform field area and make sure the direction of the antenna perpendicular to the uniform field area as in figure 5:Uniformfield area3mFigure 5d) 天线水平位置的定位Locate the horizontal position of the antenna分别记录天线水平极化的天线四角在暗室地面的上垂直投影点H1、H2、H3、H4及天线底座三脚所在位置1、2、3,同时记录天线四角距地面的高度h H 如图所示；Record the horizontal position of the antenna as in figure 6, the vertical projection of the 4 angel of the antenna are marked as H1 to H4, and the position of the tripod are marked as 1 to 3. The heights of the 4 antenna angel are also recorded.Figure 6123H1H2H3H4h He) 天线垂直位置的定位Locate the vertical position of the antenna分别记录天线垂直极化的天线四角在暗室地面的上垂直投影点H1、H2、H3、H4及天线底座三脚所在位置1、2、3,同时记录天线四角距地面的高度h v.如图所示；Record the vertical position of the antenna as in figure 7, the vertical projection of the 4 angel of the antenna are marked as V1 to V4, and the position of the tripod are marked as 1 to 3. The heights of the 4 antenna angel are also recorded.Figure7f) 连接电缆的定位Locate the connection cable连接电缆，并记录电缆途径关键点，如下图；Connect the signal cable to the antenna, and the point where the cable pass by should be record as in figure8:31 2V1V2V3V4H VFigure 8g)从80MHz开始，将场强探头放在某一均匀域测量点上（如22位置），给天线供以一定前向功率信号Pc，使得在场强探头上测得的场强值约为所需计量的场强值Ec（如10V/m）Position the sensor at one of the 16 points in the grid ( for example 22), and set the frequency of the single generator output to the frequency 80MHz. Apply a forward power to the field-generating antenna so that the field strength obtained equals Ec(for example 10V/m).Record the forward power and field strength readings.h)以1%的前一频率为步长，重复步骤g），直到频率到达1GHz，生成的频率和输入前向功率的表格如下：Increase the frequency by 1% of the present frequency, and repeat step g) until the frequency reach 1GHz. The forward power and the field strength reading should be record in table 1.Table 1i)将探头分别移到移到网格中的其他15个位置，给天线供以上表1中的前向功率的信号Pc，记录15个点上测量的每个频点上的实测场强，记录在下表中；Move the sensor to other 15 positions in the grid. At each of position, the forward power in table1 should be used. And the measure field strength should be recorded in table 2Table 25数据处理：The calculating procedure:a)将表2中的测量场强值按从低往高排列,如表3；Sort the 1 field strength into ascending order as in table 3:From low to hightable3b)分别计算从小到大连续12个场强的最大场强差值R1至R5；Calculate the field strength deviation R1 to R5 of continuous 12 point from low to high as following formula, and the data should be recorded in table 4:R1=20log(e12/e1) R2=20 log(e13/e2) R3=20 log(e14/e3)Table4c)场强差值从R1向R5，第一个小于6dB的值对应的最小场强值(表4中)作为场地均匀性校准的参考场强E T，并记录在下表中：Check the field strength deviation R1 to R5, the first one less than 6dB should be marked andTable 5d) 利用下列公式得到测试场强E C 所对应的前向功率P c ；Calculate the calibration forward powers as following formula, and record them in talbe6:)/log(20t c t c E E P P +=Table 6。
