On-site measurements remain the only option for measuring radiated disturbance from large-sized equipment that cannot be delivered to a standard testing site and/or cannot run anywhere except the operation place. CISPR-16-2-3 standard describes the direct and substitution approaches to the on-site measurements in general, however, obtaining the actual far-field strength values comparable with standard limits still is a challenge due to the list of factors including random wave propagation, unpredictable reflections and interference, available measurement distance comparing to the size of the equipment, and high level ambient noise. This paper describes the method that was developed and applied for on-site measuring of radiated emissions in 30–1000 MHz frequency range using a compact reference E-field source to define the wave propagation conditions. The findings show that a random site can be described with a statistically obtained relatively stable path loss value similar to the site attenuation of standard testing sites, and narrow-band ambient noises can be detected as outliers within the statistical analysis.