本文件描述了设备检查和射频（rf）电磁场测量程序，用于评估安装在用户设施中的rf工业、科学和医疗（ISM）设备。此处使用的术语“ISM设备”包括为无线电通信以外的目的产生射频能量以引起物理、化学或生物变化的设备；例如，工业加热器（电介质和感应）、医疗透射学、超声波设备、射频等离子体设备和射频稳定焊机。这些程序旨在帮助确保设备不会干扰无线电通信、导航和其他基本无线电服务。负责测量的工程师应采取一切合理的预防措施，以确保测量了受试ISM设备（EUT）的最大排放量。如果存在以下任何情况，可能需要对已安装的ISM设备进行射频场强测量: 1） 制造商未测量EUT的发射。2） 由于尺寸或特殊操作条件，EUT无法在安装前进行测试。3） 已安装的ISM设备涉嫌造成干扰。4） ISM设备的改进可能会影响其射频发射。5） 随着设备的老化，其持续合规性存在问题。6） 由于设备的排放物，附近人员的安全存在问题。测量应在精通射频场强测量和解释的工程师的指导下进行。这些测量是在设备在其使用地点安装并准备好使用后，以及按照2.2所述对其进行检查后进行的。测量报告通常应在进行新测量或设备不再使用后至少保存三年。电磁兼容性（EMC）和电磁干扰（EMI）工作中常见的“开放场”或消声室测量值与其他测量值之间存在显著差异- 已安装ISM设备的现场测量。下面介绍其中一些差异。1） 由于测量位置拥挤、周围墙壁和设备的反射以及其他来源的信号，测量条件通常更加困难。2）合理利用墙壁和其他设备提供的屏蔽，这些设备位于被测ISM设备（EUT）和需要场强信息的位置之间。虽然一面墙的影响可能很小，但其他设备和建筑结构的总体影响可能很大。在任何情况下，都不必以消除这种屏蔽好处的方式进行测量。有些设备被设计为在屏蔽外壳中运行，要么是因为其自身对外部干扰的敏感性，要么是因为其发射特性。测量该设备的辐射时，在设备处于正常工作位置的情况下，在外壳外部进行测量，以利用外壳的衰减。 3） 由于测量设备在一组测量过程中多次断开、移动和重新连接，因此应经常检查其校准。4） ISM设备通常可以分组进行场强测量，为整个组进行一组测量。5） 由于缺乏对测量环境的控制，已安装ISM设备的电磁辐射测量通常比实验室（露天场地或试验室）测量的精度要低得多。

This document describes equipment inspection and radio frequency (rf) electromagnetic field measurement procedures for evaluation of rf industrial, scientific, and medical (ISM) equipment installed in the user's facility. The term, "ISM equipment," as used here, includes equipment that generates rf energy for purposes other than radio communications, to cause physical, chemical, or biological changes; for example, industrial heaters (dielectric and induction), medical diatheremy, ultrasonic equipment, rf plasma devices, and rf stabilized welders. These procedures are designed to help ensure that the equipment does not interfere with radio communications, navigation, and other essential radio services. The engineer responsible for the measurements should take all reasonable precautions to ensure that the maximum emission from the ISM equipment under test (EUT) has been measured. Radio frequency field-strength measurements of installed ISM equipment may be required if any of the following conditions exist: 1) The emission from the EUT was not measured by the manufacturer. 2) Because of its size or special operating conditions, the EUT could not be tested before installation. 3) Installed ISM equipment is suspected of causing interference. 4) ISM equipment has been modified in a way that could affect its rf emissions. 5) As the equipment ages, there is a question about its continued compliance. 6) There is a question about the safety to nearby personnel because of the emissions from the equipment. Measurements should be made under the direction of an engineer skilled in making and interpreting rf field-strength measurements. These measurements are made after the equipment is installed and ready for use at its place of use, and after it has been inspected as described in 2.2. The measurement report should generally be kept on file for at least three years after new measurements are made or after the equipment is no longer in use. There are significant differences between the "open field" or anechoic chamber measurements common in electromagnetic compatibility (EMC) and electromagnetic interference (EMI) work and the on-site measurements of installed ISM equipment. Some of these differences are described below. 1) The measurement conditions are usually more difficult because of crowded measurement locations, reflections from surrounding walls and equipment, and signals from other sources. 2 2) It is reasonable to take advantage of the shielding provided by walls and other equipment located between the ISM Equipment Under Test (EUT) and the location at which field-strength information is required. While the effect of a single wall may be small, the total effect of other equipment and building structures may be significant. In any case, it is not necessary to make measurements in a way which eliminates the benefits of this shielding. Some equipment is designed to be operated in a shielded enclosure, either because of its own sensitivity to outside interference, or because of its emission characteristics. When measuring the emission from this equipment, take advantage of the attenuation of the enclosure by making the measurements outside the enclosure, with the equipment in its normal operating position. 3) Since the measurement equipment is disconnected, moved, and reconnected many times during a set of measurements, its calibration should be checked frequently. 4) ISM equipment may often be grouped for field-strength measurements, taking one set of measurements for the entire group. 5) Electromagnetic-emission measurements of installed ISM equipment are usually significantly less accurate than laboratory (open field or test chamber) measurements because of lack of control of the measurement environment.