Whats the farthest distance that a Radio Frequency (RF) singal can be transmited?

Question

I'd like to know what particular RF device / technology has the greatest distance ability. I've come to learn that certain RF technology chips / modules are only good for transmitting a couple of inches away where others can reach 1 to 3 meters. I'm trying to find a RF chip / module / technology that has the ability to reach approximately 30ft in distance.

Answer 1

Depends on several factors including the wave length, transmittting power, and the antennas.  

Radio transmissions made it to and from the moon.  With the right antennas people have gotten 802.11g wi-fi equipment to communicate over 10 miles.

What's the frequency Kenneth?

Answer 2

Cell phones can transmit for several miles.  Automotive key fobs routinely transmit 20 to 60 meters.

Answer 3

It depends on power level and the ability to detect a signal. with a very large dish we can detect cosmic background radiation  which has travelled across the universe 13.7 billion light years way.

Answer 4

try a laser. When I was in college I shot a laser beam several hundred feet away and captured the signal and stripped the data out of the laser and ran a device. They make devices that detect lasers and it makes it nice because a laser is coherent light.

I also modulated a laser beam, which I was told couldn't be done...it sounded like c**p but it came out and we could hear it. The digital stuff we passed worked great

Answer 5

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

Radio astronomers can listen to radio frequency signals from the edges of the universe.  The Universe is 93 billion light years across.  

For RF propagation that is contained within the earth's atmosphere then see the link http://www.fcc.gov/Bureaus/Engineering_T...

In general a lower frequency gives less Free Space Loss, thus having less attenuation.  Which mean the receiver would not have to work as hard to detect the signal given a fixed transmit power.

Answer 6

Infinity, and beyond!

Kind of.