antenna-theory.com

[admin]

Here's an article discussing long range high data rate communication for urban areas:
http://9to5mac.com/2011/07/29/next-gen-wifi-will-let-you-connect-to-a-time-machine-60-miles-away-and-ditch-your-cellular-data/#more-85771

Basically, you'll be able to connect at WIFI speeds with Wireless Regional Area Network (WRAN) [IEEE 802.22 technology]. To do large distances, you want low frequencies - high frequency energy has a faster rolloff with distance.

The operating band will be anywhere between 54-862 MHz.

[wolberine]

Are there any vendors who make chips for this?

Sounds like a good "Engineers without Borders" project.

[riya]

Current flows back and forth on the dipole. The charge is stored on the ends and changes in magnitude sign back and forth between the two ends. The flow of charge is current.