Again, BOTH, tho, usually, sensitivity is expressed in Micro-Volts, but
the dB range also holds. And, to further confuse facts, sensitivity ,
at VHF/UHF/Microwave, uses Noise (figure/factor), which refers to a
Perfect Reciever (no internal noise), vs. your front end rf stage, or
at your antenna's output, before coax loss's and other things (like
BACKGROUND Received NOISE, ect.) Jim NN7K


Robert11 wrote:
Hi Roy,

Thanks for reply re my older post on db question. Very clear explanations
by all.
Will put this as a new thread, though.

New at this, and relize I'm not thinking about this the correct way,
probably.

Relative to a receiving antenna's signal: what does the receiver actually
respond to; power or voltage at its input ?

Bob

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If the attenuation is given as, e.g., 2 db, what Percentage therefore
of a received signal is "lost"
going thru the coax length ?


100 * (1 - 10^(-dB/10)) ~ 37% is the fraction of power lost.

100 * (1 - 10^(-dB/20)) ~ 21% is the fraction of voltage lost.

These assume that the coax is terminated with its characteristic
impedance.

And you don't need to put "lost" in quotation marks. It is truly lost as
a signal, having been turned into heat.

Roy Lewallen, W7EL