It is difficult to predict where the effective measurement plane is situated with dome-shaped diffusers often used in commercial photometers and radiometers. Insufficient knowledge of this plane could lead to large systematic errors in calibration of the illuminance responsivity of photometers. We propose a method that can be used to determine this reference plane accurately, based on the inverse-square law between the measured signal and the distance from the source. The method is demonstrated with three commercial photometers with dome-shaped diffusers of different geometries. By taking into account the measured shifts of the reference planes (5.0 +/- 0.5 mm, 7.8 +/- 0.3 mm, and 8.5 +/- 0.7 mm), we reduced the systematic measurement errors up to 2% to statistical uncertainty components at the level of 0.2%.

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An experimental plane-wave-based method (EPWBM) is extended to use measurement based double-directional channel models in the evaluation of the antennas at 5 GHz frequency range. The method enables a statistical antenna evaluation without performing long routes of radio channel sounder measurements to be carried out separately for the testing of each antenna systems under test. The method enables more comprehensive antenna evaluation in a significantly shorter period of time compared to direct measurements. For validation purposes, the results obtained with the EPWBM are compared with the results of direct radio channel measurements. The method is shown to be sufficiently accurate for comparing the performance of different antenna configurations.

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