What are the advantages of using
both polarities for the same signal in a good LOS environment?

There isn't.
But having one on standby means, that when someone deploys on that channel/pol, in seconds you can switch polarities, to get past it. Broadcasting on DualPols, does have benefits in NLOS environments. However, the antenna design is more critical for transmitting on both at the same time. Often the Dual Pol antenna is used to create Circular polarity, such as the higher end Proxim Dual Pol gear. Or Orthogon that may compare signals to self correct them.

Tom DeReggi


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tom DeReggi
Sent: 17 January 2006 18:08
To: WISPA General List
Subject: Re: [WISPA] Multiple Radios on Single antenna

I'm not saying there isn;t a benefit now and then sharing a Dual pol antenna

between two freqs, otherwise nobody would make them. BUt....

We have found most tower agreements also, have restrictions in the agreement

that disallow using multiple radios our spectrum ranges on the antennas
without paying for that as a second antenna, even though taking up only one
antenna position.

We found that its just as easy to sneak/put up a second antenna, without
managers knowledge as it is to put up a dual freq antenna without them
knowing.  So normally you gotta pay regardless, if you do it honestly. It
becomes an issue of wether you are honest about what you put up, versus
sneaking up extra options without paying. Wether its spectrum or antennas is irrelevant. Most tower owners don't audit their sides regularly because
its jsut to expensive and even if they do, the auditors often are over
worked, and don't always check thouroughly what they are required to
supposed to check.  Most colocators also aren't short on antenna space, so
they are really charging you based on the value you are receiving being
there, not really the actually antenna space. Although special cases do
apply such as with windload requirement of over weighted towers or towers
like clock tower that have a limited number of window openings for the
antennas.

I also find saving money isn't that much of a savings because the antenna
makers then also charge more for the dual pol antennas to counter most of
your planned savings.

However, saving on time, clearly is an option, with only one antenna to
carry and bolt up. However you may run into issues, where the alignment of the antennas may need to be varied to get optimal signal based on wether you

are aligning for 5.8 or 2.4. So because we like to engineer for OPTIMAL
signal, apposed to compromised mostly best signal, we prefer to use seperate

antennas.

As a disclaimer: We pay for all our colocated antennas at our cell sites,
and we do that because we honor our tower relationships, and have negotiated

good terms, and do not want to abuse the trust they have in us, so we
maintain good relations. I mention sneaking up antennas only because, every

once in a while, we may have sneaked up an antenna to do the inital testing
(which often requires it left there for a few days), so that we can avoid
the lengthly antenna request process and timely paper work until after we
are certain that the link is doable and tested.  We justify sneaking the
antenna up, because not only are we saving us time, we also are saving the
management a lot of time, preventing the need to do paperwork
unnecessarilly, if we are unsuccessful in pulling off the link we
engineered.   I do not advise attempting to pull one over on Management
companies. If the Management company does not care what spectrum gets used,
and charging just for the antenna space, the more power to you for being
smarter.

Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband


----- Original Message ----- From: "Chadd Thompson" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Tuesday, January 17, 2006 10:30 AM
Subject: RE: [WISPA] Multiple Radios on Single antenna


Who sells dual band antennas? That could save some money on tower space
and
simplify some installations.

Thanks,
Chadd

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Tom DeReggi
Sent: Tuesday, January 17, 2006 9:19 AM
To: WISPA General List
Subject: Re: [WISPA] Multiple Radios on Single antenna


.  However, I am aware of many successfuly
using 2.4 and 5.8 from the same antenna.


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