Signal Strength Display on Ultralight Receivers
Many Ultralight receivers include a display of signal strength and S/N for the received signal. This information is useful, although it doesn't accurately show the field intensity of the signal arriving at the receive antenna.
The display of signal strength on the receiver is labeled as "dBµ," which is easily mistaken to mean dBµV/m. The correct S.I. unit for values of field intensity is V/m, or its sub-units such as mV/m and µV/m.
The dBµ display on the receiver is showing the value of a conducted r-f voltage based on the output signal of the receive antenna, rather than the value of the received field intensity that produced it. The "antenna factor" of the receive antenna needs to be known for each frequency, in order to accurately determine the field intensity of the signal arriving at that antenna.
The link below leads to an example of the differences between the signal strength display on one of the Tecsun PL-310 ultralight receivers and the field intensities arriving at its receive antenna, for the conditions shown there.