In article
,
Daniel wrote:

But what does the receiver get when it uses an antenna? Is there a
notion of reciever gain of an antenna?

Daniel-

I think the easiest way to see this is by looking at the transmitted
power having a value at the receive antenna, of so many Watts per square
meter power density. The receive antenna presents an "effective" area
of so many square meters. Its value depends on things like frequency,
antenna size, gain and direction.

Multiply transmitter power density at the receive antenna, by the
receive antenna's effective area to get received power.

But how do you determine your antenna's effective area? That isn't so
easy! I understand a half wave dipole has an effective area of about
one half wavelength times one quarter wavelength in the direction of the
antenna's major lobes. On 40 Meters, that would be 200 square meters.

Once all the factors are known, you can reduce the calculations to
Decibels.

Fred
K4DII