Quote: Originally Posted by
blackcobra487 
There should be some other way to get long range wireless. I remember when my dad was driving an 18 Wheeler. He said he was talking to someone 9 miles away on a CB radio. What is it about WiFi that makes it so limited? I would guess it's because WiFi isn't intended for this kind of use. Maybe CarPCs will become popular enough that something better will become commercially available at an affordable price.
The physics of the two radios are different.
Radio waves are a form of energy. That energy can be transmitted. An example of this is a microwave oven. My microwave transmits 1000 watts of energy into the food inside it. The energy from the waves causes the food to cook.
A WiFi transmitter is about 1 watt, much, much lower power. A CB radio is limited to a maximum of 4 watts output. Thus, it has 4X the power of a WiFi transmitter. AM radio stations can be as much as 50,000 watts.
Lower frequency radio waves travel farther than higher frequency waves. A CB radio transmits on AM while the WiFi is basically FM. CB's transmit in the 27 megahertz band -that's 27,000,000 cycles per second while WiFi is 2.4 gigahertz - that's 2,400,000,000 or an order of magnitude higher. Pretty close to the microwave band, which is why a microwave oven can interfere with your WiFi transmitter.
So, there are at least two things going against WiFi -short wavelengths at low power vs. CB which transmits long wavelengths at higher power.
Lastly, CB's transmit analog data while WiFi transmits digital data. A little interference listening to a CB transmission is no problem. A little interference on WiFi keeps the channel from working properly or slows it down substantially.
There is a new technology called WiMax that is more suitable to a several mile transmission range but it is not the same thing, will most likely be rolled out by telecom providers, and is not in widespread use yet.