Rebuldela Gregorio, Jargon Jeffrey A
National Institute of Standards and Technology, Boulder, CO 80303.
J Res Natl Inst Stand Technol. 1992 Nov-Dec;97(6):673-687. doi: 10.6028/jres.097.031.
The National Institute of Standards and Technology has established a measurement capability to support high power systems and devices. The automated wattmeter calibration system operates at power levels of 1 to 1000 W for frequencies from 1 to 30 MHz and 1 to 500 W from 30 to 400 MHz. A cascaded coupler technique is used to extend power measurements to high levels which are traccable to a 10 mW standard thermistor mount. This technique uses an arrangement of nominal 10, 20, 30, 40, and 50 dB couplers with sidearm power meters. The initial step transfers the calibration of the 10 mW standard to the 10 dB coupler/power meter. The standard is then replaced with a wattmeter to be calibrated. RF power is increased 10 dB and the calibration is transferred to the adjacent 20 dB eoupler/power meter. This sequence is repeated with the remaining coupler/power meters until the wattmeter is calibrated at the desired power levels and frequencies. Power ratios calculated from simultaneous power measurements made at each transfer are used to calculate the incident power at the wattmeter. Due to nonideal components, corrections are made for nonlinearities, mismatch, and other errors. Two types of wattmeters have been evaluated at selected frequencies and power levels. Total uncertainties are based on the random and systematic components.
美国国家标准与技术研究院已经建立了一种测量能力，以支持高功率系统和设备。该自动功率计校准系统在1至30 MHz频率下的功率水平为1至1000 W，在30至400 MHz频率下的功率水平为1至500 W。采用级联耦合器技术将功率测量扩展到可追溯至10 mW标准热敏电阻座的高水平。该技术使用标称10、20、30、40和50 dB耦合器与边臂功率计的组合。第一步将10 mW标准的校准传递到10 dB耦合器/功率计。然后用待校准的功率计替换标准。射频功率增加10 dB，并将校准传递到相邻的20 dB耦合器/功率计。对其余的耦合器/功率计重复此序列，直到在所需的功率水平和频率下校准功率计。根据每次转换时同时进行的功率测量计算出的功率比，用于计算功率计处的入射功率。由于元件不理想，需对非线性、失配和其他误差进行校正。已在选定的频率和功率水平下对两种类型的功率计进行了评估。总不确定度基于随机和系统分量。
