Deterioration of radio signals

[alexprior]

If loads of people all tuned into the same radio signal would the signal progressively worsen until no new listeners would be able to tune in?

[MAGNUM1963]

no it wouldnt get worse, it would remain the same

[squarebear]

A radio signal is broadcast and people choose to listen. Radios merely "tune in" to the station rather than removing anything from the airwaves.

If someone spoke at a lecture. It wouldn't matter if one person listened or 20,000. People would still be able to hear.

This question reminds me of an old gentleman I used to know who would only wear his spectacles when he had to, because he was worried he might wear them out looking through them all the time!

[alexprior]

Cool, thanks very much! I guess I can keep my glasses on as well now!

[john91]

I'm not sure if the previous answers are 100% correct, take a basic radio, the crystal set, this works without any power supply, but it gives out energy in the form of an audio signal from the headphones, this energy can only have come from the transmitter.

[alexprior]

Yes, I have thought more about this, and I think that the signal would deteriorate. All the aerials within range and directional arc of the transmitter would receive the signal regardless of whether the attached reciever was turned on or tuned in to the particular broadcast. When the electromagnetic radio wave strikes the aerial it must impart some energy to the aerial or else the reciever would not know what it had to translate into audible sound, whether the top 40 or a tone or whatever. As energy cannot be created or destroyed, each time the wave strikes an aerial then an amount of energy must be lost to the aerial and it would eventually run out.

I think, therefore, that recievers behind all the other aerials, listening or not, would possibly eventually have too weak a signal to convert. Of course, the signal would also be absorbed by and bounced off other surfaces to further add to its reduced energy, therefore making the effect of the other receiving aerials difficult to actually measure.

I don't know about crystal radios, but if they have no other power, then yes, they must be sourcing the energy from the radio wave.

[Toureman]

Perhaps you can work it out from this formula in the link, I can't !



http://en.wikipedia.org/wiki/Signal_strength

[grasscarp]

Alex. I dont understand your reasoning at all. The signal giving out doesnt deteriorate or impart energy. People have tried to explain it to you but you are carrying on with your own flawed assumptions. You cannot reinvent the laws according to what you think and suggest that you read up on what actually happens in the case of radio signals transmission and reception. The strength of transmission relates to the power of the transmitter and is not weakened by the number of listeners or receivers.

[john91]

Have a look at this grasscarp,
http://en.wikipedia.org/wiki/Wireless_energy_t ransfer
How do think a crystal set works if it doesn't absorb energy from the transmitter? What about a microwave oven, just a transmitter, aerial and a receiver, in this case the receiver is food, all radio transmitters transmit energy, and most things will absorb this energy, including humans, note all the health scares, if you get close enough to a powerful radio transmitter fluorescent tubes will light up on their own. In practice radios will absorb microwatts and transmitters will give kilowatts, BBC at Droitwich 500 kW for example, so you don't notice any difference.

[pug100]

Alexprior,

What most posters have missed is ground attenuation, in other words what effect the ground has on the radio wave over a certain distance. This is also known as path loss and is mostly across rough terrain / cities, least experienced over the sea as this reflects the radio energy rather than absorbs it.

http://en.wikipedia.org/wiki/Path_loss