Re: wifi-plus antennas, was VT problem

Here is a good question.... about antennas
I am also very familiar with the DBS and the older BUD satellite systems
Why did the 2 DBS companies go with left hand and right hand circularly 
polarized
antennas ???

And I did not by the over priced circularly polarized antennas that is out 
there
for my link... I used the $80 specials 25 db gain antennas...
and they work even under snow.... unless it is wet....
And that problem happens on the DBS satellite systems...
and the Big Ugly Dishes as well.... worse on ku....


Franklin S. Werren  www.bagpipes.net   www.chautauqualake.net

My 2 cents: Never get caught between an ISP and a telco in a pissing match!!
                   The customer looses every time!!!




----- Original Message ----- 
From: "Jim Thompson" <[email protected]>
To: "SeattleWireless Talk List" <[email protected]>
Sent: Wednesday, January 26, 2005 7:21 PM
Subject: Re: wifi-plus antennas, was VT problem


> David Josephson wrote:
>> It's too bad that the antenna people in this business so often make their 
>> case with so much smoke and noise that the average user can't tell what's 
>> real and what's fluff. Wifi-plus is nothing more or less than stacked, 
>> radome-enclosed, more or less circularly polarized, array antennas such 
>> as have been used for FM broadcast for 40 years or more. There is some 
>> benefit to this, particularly in urban areas, but no antenna is magic, 
>> and no antenna is going to make pine needles and leaves disappear. Any 
>> antenna produces "gain" solely by directing more of the power you feed it 
>> in one direction and less in others; a circularly polarized antenna can 
>> actually result in lower signal strength because part of the signal is 
>> radiated in a polarization that isn't received by a given, optimal, 
>> receiving antenna. Over a point-to-point link you're not going to do any 
>> better than well matched parabolic antennas aligned to the same 
>> polarization.
>
> Well-said.  Agreed, even.   (Though if you match the polarizaion of any 
> two antennas, you'll not see the effect you state.)  That, and you'll need 
> to restrict "do better" to "have more link margin", since the higher 
> directivity may actually lead to more OBSS interference, since the other 
> STAs won't see a high-enough signal level to set CCA.
>
> But I digress.
>
> I was 'holding back' not wanting to provoke a vendor war.
>
> There is a *lot* of BS in the wireless world.
> _______________________________________________
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>
>
> 


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