On Fri, 26 Sep 2008 02:45:59 -0700 (PDT), Penang
wrote:

Since I'm toying with a community-type of wifi network, there are
walls, and foliage, and topologies (hills and valleys) that are
effecting the way the waves work.

2.4GHz wireless does not go through hills. If you plan to have
coverage in the valleys, you'll need to have a radio somewhere in the
valley. NLOS (non line of sight) radio can be made to work, but
cannot be made to stay working. It may work for a while. Then,
something is moved, and it stops working. If you want to fill in
holes, look into wireless mesh networks.
http://www.open-mesh.com
http://meraki.com

I suggest you look into sector antennas, specifically AMOS or Franklin
antennas. These are quite suitable for covering a wide flat area.
Depending on construction, the horizontal beamwidth is anywhere
between 90 and 150 degrees, with a vertical beamwidth of approximately
10 degrees. The idea is to send most of the RF toward the horizon,
and not into the air or into the ground. Gain varies from 8dBi to
perhaps 15dBi depending on type and construction.

Articles on the AMOS antenna design at:
http://www.qsl.net/yu1aw/invertamos.pdf
http://www.qsl.net/yu1aw/amos_article.pdf

AMOS and Franklin type antennas:
http://pe2er.nl/wifisector/
http://yu1aw.ba-karlsruhe.de/ANT.htm
http://yu1aw.ba-karlsruhe.de/vhf_ant.htm
http://www.qsl.net/yu1aw/vhf_ant.htm
http://www.brest-wireless.net/gallery/AntenneAmos
http://www.brest-wireless.net/wiki/materiel:amos

You'll find that there's much more to running a WISP (wireless
internet service provider) than antennas and radios. If you plan to
grow the business, you'll find that it's exactly the same as a wire
line ISP, except you have a basically unreliable method of delivery.
One leaky microwave oven will trash connectivity for a very wide area.
Like a wire line ISP, you'll need a backhaul, billing, support,
installation, service, and troubleshooting. The usual oversight is
that wire line ISP's don't make much money from connectivity. They
make their money with secondary services such as web hosting. If
customers bring their own equipment, you'll need some way to
troubleshoot *THEIR* problems and possibly charge for fixing *THEIR*
computer. You could supply the radio equipment to the customers which
will put you in the equipment leasing business. Plenty to think about
but the one that usually causes problems for startup WISP's is "who is
going to answer the phone when the customer calls to report an outage
at 2AM?" Start reading about the WISP business he
http://www.bbwexchange.com/wireless_internet_access/
http://www.bbwexchange.com/howto/

Good luck.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558