EN 55014-1 标准解读2

但是关于3m和10m的换算的限值，是否真的完全等效，我以前看过一篇文章来解析，请大家参考下：

文章如下：

3m场地的辐射数据可以直接代替10m场地的数据吗？

One problem with 3m testing is that there is a fall-off projection problem that is usually seen below 200 MHz in vertical polarization. if tested at 3m, the maximum vertical field propagates along the ground plane (normal to the ground plane) due to the reflection. Since the antenna is scanned between 1 and 4m, some of the energy goes under the antenna.



At 10m the wavefront is more developed and with the same scan window, 1 to 4m more of the main lobe of the total field propagating on the ground plane is measured. the 3m data has to subtract 10 dB from the measured data to account for the 3 to 10m fall-off. But that is free-space assumption without the ground plane effect.



At 10m, more of the energy is measured and when compared to the projected fields done at 3m, up to 7 dB errors have been reported. the 3m data actually underpredicts the field at 10m. This has caused products that were thought to pass when tested at 3m to then fail at 10m facilities.



This is not much of a problem in horizontal and actually the opposite problem exists with 3m measuring more energy than will be seen at 10m. But the differences are much less. The other reason this is not a bigger problem at 3m, is that there is not much horizontal emission below 100 MHz since the horizontal fields on the ground plane are zero. the direct and reflected are 180 degrees out of phase on the ground plane and cancel. So emissions are measured up around 4m in height for horizontal plus products don't tend to efficiently radiate horizontal fields below 100 MHz.



        以上信息是某位国外资深EMC工程师对3m/10m半电波暗室场地测试结果的比较，从测量模型分析了为什么3m的数据和10m场的数据不同，以及对3m数据转换成10m数据的看法。

       我个人认为，在某一场地测试的数据，不同简单地通过加10或者减10进行相互换算，因为10dB这个数据是来自自由场（free-space ）的模型。

4.1.2.3 Application of the limits：（RE)限值的应用
4.1.2.3.1 General
This subclause describes application of the limits for all appliances (see Figure 10).
Regulating controls which incorporate semiconductor devices, electric fence energizers,
rectifiers, battery chargers and converters, which do not contain any clock frequency higher
than 9 kHz, are not subject to the requirements in the frequency range 30 MHz to 1 000 MHz.

4.1.2.3这个条款讲述的是限值的应用。

一般情况下，所有的产品都是要测试RE的，这句话是总论。
但是对于半导体设备控制器、电栅栏激发器、整流器、电池充电器和转换器等器件，如果时钟频率不超过9k，则是不需要测试30M-1000M的的RE的。

其实在实际情况中：家电中很少有测试辐射的。一般情况下，骚扰功率中table2a和table2b的限值都是满足的。

4.1.2.3.2 Mains operated appliances
The equipment under test shall be evaluated for emissions in the 30 MHz to 1 000 MHz range
by testing in accordance with either method a) or b), see also Figure 10.
对于电源供电类器具，测试流程的选择，如下图

a) The limits in columns 2 and 3 of Table 2a for the frequency range from 30 MHz to 300 MHz shall be met by all appliances except for electric tools. For electric tools the particular limits given in columns 4 to 9 of Table 2a apply according to the rated power of the motor, excluding the power of any heating device (for instance heating power in a blower for plastic welding).Appliances are deemed to comply in the frequency range from 300 MHz to 1 000 MHz if both of the following conditions (1) and 2)) are fulfilled:
1) all emission readings from the equipment under test shall be lower than the applicable limits (Table 2a) reduced by the margin (Table 2b);
2) the maximum clock frequency shall be less than 30 MHz.
If either of condition 1) or 2) is not fulfilled, radiated measurements in the frequency range from 300 MHz to 1 000 MHz shall be conducted and the limits of Table 3 for that range applied. In any case the limits of Table 2a in the frequency range 30 MHz to 300 MHz
shall be met.

该条款讲述的就是RE测试骚扰裕量的关系：
有两个条件:
1、满足200M-300M频段的裕量。
3、时钟频率小于30M。（对于这个条件，其实依据现在家电的技术条件，完全可以忽略，因为现在的家电的始终频率远远小于30M，一般是4M或者是8M.但是以后技术继续发展了，可以就需要考虑条件2了。）

同时需要注意的是：如果两个条件不能同时满足，则需要测试RE。

b) The limits in Table 3 shall be met. Any of the measurement methods mentioned in Table 3 can be selected by the manufacturer except that the TEM-waveguide shall be used only for battery powered appliances not intended to have external cables attached (see also Note c in Table 3).
The test report shall state which method was used and which limits were applied.

该条款是讲RE测试方法的选择的。测试的流程请参照上面的图片RE flow chart。  

需要谨记的是，TEM小室只用没有外部连接线的电池类器具。

4.1.2.3.3 Battery operated appliances
For all battery operated appliances the limits in Table 3 apply for the frequency range from 30 MHz to 1 000 MHz (See also Figure 11). Any of the measurement methods mentioned in Table 3 can be selected by the manufacturer except that the TEM-waveguide shall be used only for battery powered appliances not intended to have external cables attached.
The test report shall state which method was used and which limits were applied. Battery operated appliances which do not contain active electronic circuits or motors shall not be measured. These appliances are considered to comply without testing.

NOTE Examples of active electronic circuits include circuits containing transistors, thyristors and relays. A LED connected to a battery via a manual switch is not an active electronic circuit if the current is limited only by a resistor or a transistor operating linearly, but it is an active switching circuit if the current is pulsed using a transistor.

4.1.2.3.3条款讲述的是电池供电类器具的RE测试方法的选择，尤其注意的TEM只用于电池类器具的测试，但是电池类器具的RE并不是只用TEM小室测试，具体的测试方法的选择，请参照下面的流程图：