Hi,

I would recommend that you do some research on the terms "dynamic range" and
"front-end compression" as it relates to your particular hardware / radio
platform.  Understanding those terms / concepts will give you the
understanding you need to make your "homebrew" system work

Otherwise, if you want to just "plug and pray" your network -- you're better
off probably just buying quality name brand products that have enough
built-in "safeties" to let one just mindlessly deploy

-Charles

P.S. -- although I happen to have an understanding of Rf theory, HAM stuff,
and Radio engineering, when I ran my WISP, I found that in the long run, it
made better business sense to subscribe to a "lazy" WISP "plug-and-pray"
mentality due to the fact that I liked knowing that I could focus my core
efforts on sales, marketing and customer service.  From a deployment side, I
could just put some stuff up and have the ability to blame all my system
mishaps on my friendly manufacturer / vendor =)


-------------------------------------------
WiNOG Austin, TX
March 13-15, 2006
http://www.winog.com 



-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Bob Moldashel
Sent: Tuesday, January 17, 2006 6:25 PM
To: WISPA General List
Subject: Re: [WISPA] Multiple Radios on Single antenna


Ahhhhh......Lets do some math.......

Lets say the radio has a +20 dB output.  For this example there is no 
line loss.  The antenna is rated at 30dB x-pole isolation.  Here we go...

+20 dB
-30dB xpole
=
-10 dB receive level. 

In my book that is high enough to kill any link of the same freq on the 
opposite polarity....No???

Add to that a radio that needs to Rx and Tx on and off and you should 
have receiver blocking....... 

-B-




Matt Liotta wrote:

> Depending on various factors, you should see at least 15db of
> attenuation between polarizations on a dual-pol antenna. 
> Theoretically, you should see 20db. In any case, 15db is enough 
> attenuation even on the same channel to operate two links reliably.
>
> -Matt
>
> Jason Wallace wrote:
>
>> List,
>>
>> When antennas are separated by normal distances, they can only "see"
>> each other electromagnetically (ie, radio waves).  However, when they 
>> are close they will experience capacitive and inductive coupling.  
>> Dual pol antennas work fine when only receiving (as in those large 
>> satellite dishes from the 80's that used 90° pol changes between 
>> adjacent channels).  I think you will always have trouble overloading 
>> the receiver when transmitting with this setup.
>
>
>


-- 
Bob Moldashel
Lakeland Communications, Inc.
Broadband Deployment Group
1350 Lincoln Avenue
Holbrook, New York 11741 USA
800-479-9195 Toll Free US & Canada
631-585-5558 Fax
516-551-1131 Cell

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