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Although typically the far-field radar cross section (RCS) of targets is of interest, researchers often find it convenient to perform RCS measurements in near-field. To obtain far-field RCS using near-field measurements, traditional methods are developed based on the near-field far-field transformation (NFFFT). These methods are sensitive to various imperfections of the real-world measurement environment...
This paper presents a brief discussion of the design and development of a new WR-10 (75 to 110 GHz) rectangular waveguide microcalorimeter recently fabricated at the National Institute of Metrology, China. The new microcalorimeter will serve as the national primary power measurement system in millimeter-wave range. In this paper, its capability to measure the effective efficiency of WR-10 transfer...
This paper presents a comparative evaluation of the contribution from thermal isolation section (TIS) of a rectangular waveguide microcalorimeter into its correction factor, through different modeling methodologies. Study shows that the ratio of power dissipated at the foil short inserted between thermistor mount (to be calibrated) and interface plate and that at the walls of TIS, determined through...
A new WR-28 (26.5 to 40 GHz) waveguide microcalorimeter has been recently developed at the National Institute of Metrology, China for a replacement of previous national primary power standard. The new microcalorimeter was preliminarily evaluated and successfully used to determine the effective efficiency of a transfer standard (i.e., thermistor mount). In this paper, measurements and evaluation of...
Thermistor mounts are served as transfer standards which are calibrated in microcalorimeter. A correlation between the effective efficiency of thermistor mount and the relative humidity of the laboratory has been observed. The difference of effective efficiency measurement in 20% and 50% humidity level can be about 9 times the k=1 uncertainty. The effects of humidity on thermistor mounts can result...
In this paper, the thermoelectric conversion power sensor, which is the key part in the WR-6 (110 GHz–170 GHz) rectangular waveguide microcalorimeter, was designed and evaluated. The ANSYS simulation software was used to evaluate the quantitative relation between the THz power and DC power for the power sensor.
In this paper, the effective efficiency of the thermistor mount was evaluated by three WR-22 (33–50 GHz) rectangular waveguide microcalorimeters. Three sets of microcalorimeter were made from the same design drawing. The only difference among them was some key parts (thermal conductive plate and heat isolation section) coming from different manufactures. The relative deviation of measurement results...
In this paper, we present some preliminary results from evaluation and validation of a national WR-15 (50 to 75 GHz) power measurement system, which has been upgraded for thermistor sensor (thermistor mount) measurements recently. The system is a physical realization of direct comparison transfer technique for microwave power sensor calibration. It has been evaluated and validated referring to a WR-15...
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