increase the power on the antennas
1a2s3d4f said:
Can any one explain to me the relationship between receive power of the antenna and it gain I understand that the more gain that you get from the antenna, the more distance you can communicate.
There is no direct relationship. Received power depends on few factors:
Power radiated from transmitting antenna (linear dependence)
Distance between transmitter and receiver (complicated relation ,
for short distances it fall with the pwer of distance but also depends on working frequency )
Height above the ground level for both transmitting and receiving antenna (and falling to 0 above "critical distance" appropriate equation you can find yourself)
Directional characteristic of transmitting and received antennas (antennas gain).
Antennas and input impedances matching.
You can trade for example directional characteristic for emitted power (in stationary, point to point system)
1a2s3d4f said:
However the gain of the antenna is depend on the radiate power.
It is not true antennas gain is parameter on its own , in no relation with transmitted power (or received power).
Antennas gain (from definition) is the ability of
transmitting/receiving antenna to focus electromagnetic valve
in/from desired direction.
Good analogy is a tungsten lamp.
Its light goes all around ,
If you add a flat mirror on one side of the bulb the radiation in one direction is 2 times higher. (while there is a complete dark behind the mirror), you can say that the flat mirror is a light antenna with the gain = *2 or 10 log 2 = 3 dB (you can find a table matching ratio with dB).
You can place a bulb in parabolic mirror and you focus the light into more narrow beam. You can use a lens, take the light from bigger surface and concentrate it in small area of light sensitive cell The gain is equal to ratio of
lens surface to the
sensitive element surface.
Antennas gain is the relation between the light power from omni-directional bulb ,
and the amount of light when using mirrors , lenses and the optical devices.
As you see the Gain does not depend on the light source power.