Radio signal question?

Question

When they send a message through space to a ship that is far way, like mars, it takes so much time for it to reach.

I'm thinking that the signal must just keep going and going and never end. Someone on the moon could hear the signal, before it gets to mars

why not on earth, if you talk on the radio why doesn't that signal keep going and going and after a few hours or days later, why couldn't you hear it again, why doesn't it keep circling the earth forever

Answer 1

>why not on earth, if you talk on the radio why doesn't that signal keep going and going and after a few hours or days later, why couldn't you hear it again, why doesn't it keep circling the earth forever

Because it doesn't circle the Earth at all. The Earth's gravity is very weak compared to the speed of light, so radio signals just go almost straight outwards into the sky.

However, there is a layer of the atmosphere that reflects radio signals, which greatly increases the distance across which radio and TV stations can broadcast. However, the radio waves would have to bounce so many times to circle the Earth that probably only one in a million or a billion of the original photons could complete the trip.

Answer 2

Radio signals propagate in straight lines. They don't go "around" anything unless there is a force that deflects them. A strong gravity field (like a star's) could bend a nearby radio signal, so could an electromagnetic field.

A commercial radio station broadcasts on a specific frequency. It's signal goes out in all the directions determined by the length and shape of its transmission antenna. Some of those signals go into outer space, and a few of THOSE signals may be deflected back to Earth by the magnetic properties of the ionosphere. Some of THOSE signals could be picked up by distant receivers, or be absorbed by the Earth, or even bounce back up again. Each bounce means a weaker signal, until it can't be detected against background noise.

In the case of a signal deliberately sent into space, you are right that anyone in the signal path with the right frequency and demodulator could listen in. But space is a big place and a broadcast signal in all directions loses strength with distance. Most spacebound messages are transmitted through a directional antenna that focuses the signal into a narrow path. That way, energy is not wasted sending the signal in unlikely directions. If you are not along that path, you are very unlikely to be able to detect the signal.

Answer 3

Signals like radio and tv, move at the speed of light. So, we can hear the signal at the time it is sent because of the small distances on Earth.
All our signals, from radio transmissions to tv shows and everything ever broadcasted, are traveling even now through space. They just get fainter with distance just as with a star's light.

Answer 4

Radio signals on earth are not focused they go out in all directions. They weaken as they bounce between the upper layer of the atmosphere and the ground until static covers them up ( this is for AM), for FM they go on a straight line and leave the atmosphere so they never go around the planet.
There are radio systems that can broadcast very far - my father is in northern California and holds discussions with people in Australia and in Belgium - so some radio waves (shortwave) do make it around the planet, but they are too weak to make multiple trips


Hey Tham153 have you seen GALAXYQUEST a movie based on a race of aliens who have based their entire society on a "cheap sci-fi tv show" (obviously a takeoff on Star Trek) that they have been watching.

Answer 5

It does. It also weakens as time progresses. Just as wave will fade away, the radio signal will fade eventually. People do listen to them even after the signal was captured by a receiving device. That's how the ECHELON spy network works.

Answer 6

confident, they do. whether, you may word of antenna earnings. If the sign is very directional, it won't weaken as in the present day. So a directed radio sign can holiday lots greater. besides, a directional receiving antenna can %. up a lots weaker sign. the folk at SETI are employing very directional antenna dishes. the downside is which you would be able to in trouble-free terms "look" at an extremely small part of the sky at as quickly as. it incredibly is such as satellite tv for pc television the place your dish must be geared in direction of the satellite tv for pc. that's additionally why the satellite tv for pc must be in a geostationary orbit (or you will p.c. a monitoring antenna). So certainly a radio sign vacationing to the closest stars would be very vulnerable certainly. whether, it is not any longer unreasonable to think of that they'd truthfully be gained. even with each thing, that's what we are attempting to do (receive ET indicators).

Answer 7

The Earth depends on the solar cycle to propagate radio waves.And radio waves act differently from am to pm hours.Radio waves bounce off the ionosphere and the Earth from the transmitter to the receiver in the hf bands. vhf on up in the spectrum depend on line of sight to propagate along the Earths surface. vhf and on up pass through the Earths atmosphere, and gets lost in space, where as hf depends on certain atmospheric conditions to be useful.Inquire into amateur radio to find out how it works.

Answer 8

A radio signal is like a light signal it will go the way you direct it.
I can be intercepted or absorbed,it can be relayed,like light and a mirror.
It can be modulated to carry information.