[amsat-bb] Re: Fw: Re: More Clutter on 2.4 GHz

John B. Stephensen kd6ozh at comcast.net
Mon Oct 9 15:56:01 PDT 2006

If you're staying above the satellite segment then you're not creating 
problems for amateur satellite users. The long-term problem is that non-hams 
won't care as much, especially as usage increases, and 47CFR97.303(j)(2)(ii) 
says that we must accept interference from all other users so we can't force 
them to change frequencies. Interestingly, there is no statement that hams 
can't cause interference to unlicensed devices.



----- Original Message ----- 
From: "Nate Duehr" <nate at natetech.com>
To: "Tony Stone" <w4tas at gte.net>
Cc: <amsat-bb at amsat.org>
Sent: Monday, October 09, 2006 21:45 UTC
Subject: [amsat-bb] Re: Fw: Re: More Clutter on 2.4 GHz

> Tony Stone wrote:
>> The part 15 rules for 2.4 GHz operation state that a maximum transmitter
>> output of 1 watt with a 6 dbi omni antenna is legal. This is 4 watts 
>> eirp.
>> With a directional antenna you must decrease your transmitter power
>> 1 db below 1 watt for every 3 db antenna gain over 6 dbi.
>> Confusing as this may seem, it means that you can have 250 milliwatts
>> of transmitter output with a 24 dbi gain antenna. That is 18 db over
>> the original 6 dbi which is 6 units of 3 db each. This means that the
>> transmitter power must be reduced from 1 watt to 250 milliwatts (6db).
>> This is an effective isotropic radiated power of 64 watts and is 
>> perfictly
>> legal.
>> Check the gain of a 36 inch dish at 2.4 GHz and do the calculations to
>> see if it is legal or not.
>> 73
>> Tony
>> W4TAS
> Tony -
> Sorry if I got it wrong.  I was going off of some of Cisco's
> certification documentation for certifying their Access Points, perhaps
> they're being overly conservative on their numbers to assure
> certifications.
> I couldn't find my old link to the REAL rules so I might have been a bit
> overzealous in my numbers on the low side.
> Still: In reality it's a free-for-all... you could blast just about
> whatever you want point-to-point with gain antennas and there'd be
> little way to find that you were doing it, and even less desire to do
> anything about it.
> Sorry to the list -- mostly the only reason it relates to anything
> Satellite-related is the general noise level on 2.4 GHz, and I'm
> creating more "noise" on the list than that... (GRIN).
> Happy to take this offline if someone wants to continue.
> Nate WY0X
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