Tim Pozar writes:
> On Fri, Jan 30, 2004 at 11:53:31AM -0800, Ivan Bojer wrote:
> > Thank you all that answered this question directly to me,
> > I really appreciate it!
> >
> > Lets just continue discussion for a tad more.
> >
> > I believe that 36 dBm cap still applies!
> >
> > I am aware that P2P systems can have antennas with more
> > gain, but that is just so one can compensate for an
> > antenna feed loss. It is easy to see that P2P systems
> > might have tower with antenna feeds of up to 100 feet
> > or more. Because of that they are allowed to go above
> > 23dBi and above that have 3:1 ration (gain 3, deduct 1).
> >
> > At least that is how I interpreted the FCC rules,
>
> Not sure how you came up with this. Transmission line loss is
> typically calculated in to the gain (or loss) of the antenna system.
The way systems are certified, you measure the TX power into the back
of the antenna. Any transmission line loss is already "accounted
for".
> The argument in the NOIs and NPRM were that point to point systems
> should be encouraged as they are better "engineered" for the
> application as they tend to cover the area needed to do the job and
> not just randomly direct energy to cause more interference. They
> also will likely need to cover more distance. Hence the rules give
> p2p systems more EIRP depending on the gain of the antenna.
>
> > do you believe that 36dB cap changes in P2P completely?
> > What is the "theoretical" cap in that case (I understand
> > that making an antenna with 100 dBi might not be feasible)?
> >
> > If what you are saying is correct than this theoretical table is valid!
> >
> > PEP Antenna gain EIRP
> > 30 6 36
> > 29 9 38
> > 28 12 40
> > 27 15 42
> > 26 18 44
> > 25 21 46
> > ....
> > ....
> > 1 93 94
>
> Yup. BTW. a 93dBi antenna at 2.4GHz would be gigantic and would
> be impossible to align and keep in alignment.
Its likely that you can't build it, actually. Internal losses would
make the whole thing unpractical. Moreover, the more gain, the more
you're subject to far-off co-channel interference, and the more you
get to worry about OOB signals. ;-)
--
"Speed, it seems to me, provides the one genuinely modern pleasure."
-- Aldous Huxley (1894 - 1963)
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