wifi from radio antenna?

I could probably find the answer to this by some research, but I'm too lazy. :D We have the beginnings of free wifi in our city (Portland), though it's still spotty, at best, since not all areas of the city are 'wired.' I was thinking about how the nodes only cover about 300' each, then there's obstacles, interference, etc. Why can't they put up one big antenna, like radio stations, and pump out 50k watts, or whatever would be necessary to cover the entire city?

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You would not want one powerful station like that. You would take a cellular/mesh approach to do what you want. WIMAX cells can cover a pretty good size area.

Look up WIMAX and WISP (wireless internet service provider)

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Radio stations are one way. They have 50K watts, you just listen, you don't transmit. You couldn't have a couple thousand transmitters going back to one tower.

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... but now the wifi client in your laptop needs to be able to respond (acknowledge packet received, send a packet, etc), using its own

50kw transmitter. Really shortens battery life!
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The laptop would only need to use full power at the limit of the coverage of the station, close in the laptop would not need to use such high power.:)

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sillyputty hath wroth:

That's ok, because I'm too lazy to research a proper answer.

Are you thinking perhaps of the MetroFi system:

Ummm... we gotta work on the terminology. One does not "wire" a wireless network. I guess "install" might be a suitable substitute. Personally, I prefer to "plant" an access point, since many of mine are hidden inside fake plants, but nobody else likes the term. I'm open to alternatives.

Well, lots of reasons, some of which others have mentioned. 50,000 watts means an AM broadcast band xmitter operating on about 1MHz with a bandwidth of about 9KHz. Wi-Fi is 2,400Mhz, with a bandwidth of about 26MHz, or about 3000 times the bandwidth of the AM station. So, you could use a 50,000 watt AM transmitter to run wireless data, but it would be at the speed of a really slow dialup connection, with only one user for perhaps 100 square miles.

Need reading material on RF theory? I'm too lazy to supply a list but might be able to generate a few buzzwords that you can insert into a Google search.

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Jeff Liebermann


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Antenna (and to an extent RF theory): The ARRL Antenna Book

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Curt Christianson

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