Just checked the specs for the RadioWaves antennas that I'm having the
problems with and see that they have 28dB "X-Pol. Rejection" would this
suggest that the circuitry controlling the 2 feeds are separate? If so, is
there anything else that could be preventing us having 2 separate
simultaneous links running through these parabolics?

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Bob Moldashel
Sent: 17 January 2006 18:51
To: WISPA General List
Subject: Re: [WISPA] Multiple Radios on Single antenna

Sorry but this whole thread is going sour fast.....

1. Dual Polarity antennas work for transmit and receive. They are not TX 
only or RX only in configuration.

2. The normal isolation between vertical polarity and horizontal 
polarity can range from 10-30 dB depending on the operating frequency.

3. The biggest issues to using 2 radios on the same dual polarity 
antenna is the adjacent channel rejection, x-pole polarity, TX power 
levels and Receiver sensitivity..

4. 802.XX radios will not work on the same channel because while one 
radio is transmitting on 5825 GHz. the radio on the other polarity is 
receiving on the same channel. Considering there is only 10-30 dB of 
seperation, the radio RX levels will only be reduced by that amount 
causing receive interference.

5. We have more than 20 dual polarity links running FD radios such as 
Proxim Tsunamis operating in the same band.  Granted, they have much 
better filtering than the basic 802.XX radio but they work flawlessly..

6. We presently have 2 DP links in place with 802 style radios.  One of 
the links consists of WRAP/CM9's operating in 5.7-5.8 Ghz.  The other 
has a Proxim MP.11a on one plane and Tranzeo TR-5a on the other.  One 
link is 6.5 miles, the other is 7 miles.  There is no desense between 
radios and both operate fine without interference issues.

7. While Tom may be experiencing the tower rental issues regarding 
antennas, we have not seen this in the NE. Most leases we have 
negotiated are based around wind loading on the tower.

Like everything, dual polarity antennas have a place like all other 
equipment.  The link just needs to be engineered to operate properly.

-B-

-- 
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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