[geeks] Ultra-Portable UNIX

[Geoffrey S. Mendelson]

On Sun, Mar 05, 2006 at 03:21:44PM -0500, Patrick Giagnocavo wrote:
> You have to stay within the total EIRP and may home-build and use up to
> 5 antennas of any design.  In this case total EIRP would be higher
> because it is a point to point link and not point to multipoint.  

Total EIRP is based upon transmitter power plus (or minus) antenna gain.
If you have an antenna that is radiates 100% of of the output power,
which is quite easy to do at 2.4gHz, but has no gain, and then narrow
the beam, each time you halve the angle you double the EFFECTIVE power.
If you have 100mw at 360 degrees, it's 200 at 180, 400 at 90, 800 at 45,
1600 at 22.5, 3200 at 11.25, 6400 at 5.6, 12800 at 2.8 degrees which is
the radiation angle of a satellite dish.

So Sammy is correct, a dish antenna is not illegal, but it can easily 
go beyond EIRP ratings. On the receive side there is AFIK no restriction
on using dish antennas, YMMV via local laws.

Here in Israel it's even worse the limit is 100mw EIRP, so if you connect
a gain antenna, you must reduce the transmitter power proportionaly.

As for the pringles can antenna, if he transmitted into it, he could have
easily violate the EIRP regulations.

Just because it was NOT taught in a seminar in 2002, does not mean that
it was legal then or is now. This list is unusual in that many of the
people on it are familure with radios. Most computer people are not.

Geoff.
-- 
Geoffrey S. Mendelson, Jerusalem, Israel gsm at mendelson.com  N3OWJ/4X1GM
IL Voice: (07)-7424-1667  IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838 
Visit my 'blog at http://geoffstechno.livejournal.com/