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1. Nov 28, 2016

### physicsEnthu_123

• When antenna receive the radio signal does it reduce the actual radio signal strength or strength indeed depends on the dispersion loss and other dielectric absorption?
• If antenna doesn’t reduce the radio signal strength(power), how it generates the current in the receiving antenna circuit? How antenna in this case is not affected by law of conservation - radio signal doesn’t loose its power even generating current in the antenna.
• If antenna affects the signal strength of the radio signal, does more antenna means more power to transmit for transmitter?

2. Nov 28, 2016

### jasonRF

Yes, when an antenna receives a radio signal it is taking energy away from the radiowave. For most practical systems this is a tiny amount of energy, though. When I tune my FM radio to a signal, it has no significant effect on the signal strength available to my next door neighbor.

I'm not sure what you are talking about here - I thought you were discussing a receive antenna. What transmitter are you referring to?

Jason

3. Nov 28, 2016

### rbelli1

The energy has already been emitted so it is irrelevant to the transmitter if you collect that energy or it just continues on by. This will not be true if you are close enough for near field effects to come into play. Then you are affecting the characteristics of the transmitting antenna.

BoB

4. Nov 29, 2016

### physicsEnthu_123

So if I have satellite transmitter and my transmitting power should cover only area depending upon the dispersion loss by inverse R^2. If i have increase number of antenna does my transmitting power needs to be increased since there are losses? In other scenario if I have a close room and I have a transmitter with a fixed power. If my number of antenna increase does the reception power decreases?

5. Nov 29, 2016

### davenn

not in a measurable way ( well I would be surprised is it could be) ... there is still much more energy bypassing all those antennas (not being captured ) than what is captured.
Now if you have antennas in a line, that is different as the rear antenna will be in the shadow of the front antenna ( the one closer to the transmitter) and it will of course receive less signal