Japanese researchers have announced the development of a new national measurement standard for the calibration of ultra-high-frequency power meters in the 110-170 GHz band.
The new standard, a joint effort between Japan’s National Institute of Advanced Industrial Science and Technology (AIST) and the National Institute of Information and Communications Technology (NICT), was made possible by the development of an isothermal control technology for the measurement of RF power and DC power converted into heat and a technology for the evaluation of their equivalency.
Interest in the use of terahertz waves, the electromagnetic waves in the frequency range from 100 GHz to several THz, continues to grow in the fields of communication technology, material analysis and security, but thus far the focus has remained only on developing only a relevant frequency measurement standard. Development on a power standard has been widely delayed around the world, the AIST-NICT researchers say, and there is a growing demand to establish a primary standard to act as the national measurement standard. In addition, the need for a way to measure the spurious power in EMI tests in the frequencies (121 GHz, 153 GHz, and 159 GHz) that are double the carrier frequencies used for millimeter-wave automotive radars(60.5 GHz, 76.5 GHz, and 79.5 GHz) is resulting in a higher demand for a traceable RF power meter.
According to an AIST release, “with this measurement standard, the RF power to be measured will initially be absorbed into an electromagnetic wave absorber and converted into heat. The most accurate measurement of RF power can be made by comparing this heat to the equivalent DC power.”
“Two new technologies were developed to achieve these thermal measurements. One is a thermal measuring method using isothermal control technology, which has enabled thermal measurements to be made about ten times faster than conventional methods. With this method, highly accurate measurement results can be obtained during the relatively short time when the signal source output is stable. The other is an equivalency evaluation technology that compares the RF power and DC power that have been converted into heat. Generally, for RF power and DC power converted into heat, there is a difference in thermal distribution inside the electromagnetic wave absorber creating a difference in measured values. This time, by conducting a detailed analysis of thermal distribution difference within the electromagnetic wave absorber, a technology to accurately evaluate RF power has been developed.”
The new standard is expected to contribute to the reliability of EMI testing for millimeter-wave automotive radars and the improvement of airport security systems, evaluation methods for electromagnetic shielding materials and the ultrafast semiconductor field.
A RF power meter calibration service for wireless communication equipment based on the new standard was reportedly launched by NICT in late March.
AIST is expected to focus on developing a national measurement standard for a frequency band in excess of 300 GHz within the next few years.
