Nicom 900 link - STL Antennas Can you Mix and Match

Gotta watch those Fresnel zones!
TPT
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Re: Nicom 900 link

Post by TPT » Sat Jul 28, 2018 10:50 am

Those little OMB antennas won't be much good beyond a mile or two. Management is going to have to spend some money here. I would suggest either a Scala PR-950 pair or the Marti SC-48. The Marti is a full parabola, the Scala is sort of a half moon shape with lower gain. However, both will have greater transmit ERP and greater receive signal strength than the OMB antenna pair.

Several problems with the current set up. If you pulled the cover off those OMB antennas suspect they are little more than small Yagi's. Not much gain.
The gain of a conventional STL antenna with a parabolic reflector is several times that of a small Yagi Has the effect of increasing your transmitter ERP substantially, as well as the receive signal level on the other end.

Second problem--they are not as directional as a conventional parabola. May make them easier to line up--but if you are anywhere near an urban area (even 75 miles or less) at some point in the future you may get ducting interference from another station's STL. The parabolic reflector on a conventional STL antenna does a wonderful job of eliminating signals coming from any direction other than towards the transmit antenna.

As noted above--receive and transmit antennas need to be matched in polarity.

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kkiddkkidd
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Re: Nicom 900 link

Post by kkiddkkidd » Sat Jul 28, 2018 8:21 pm

TPT wrote:
Sat Jul 28, 2018 10:50 am
Those little OMB antennas won't be much good beyond a mile or two. Management is going to have to spend some money here. I would suggest either
And to that point but not to be a rule monger... What is the directionality requirement for new license? I seem to recall that it takes a pretty tight antenna pattern on the TX to meet the side lobe requirements and even long yagis struggle to make the required patterns for a licensed system. As in, some of the existing small paraflectors / yagi's are grandfathered but no longer legal for new systems.

Regards,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

TPT
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Re: Nicom 900 link

Post by TPT » Sun Jul 29, 2018 6:15 am

Reading the parallel threads here I doubt that the new link was either coordinated or licensed.

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NECRAT
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Re: Nicom 900 link

Post by NECRAT » Sun Jul 29, 2018 9:34 am

TPT wrote:
Sun Jul 29, 2018 6:15 am
Reading the parallel threads here I doubt that the new link was either coordinated or licensed.
Reading the parallel threads was giving me a headache. Not sure why two separate threads of the same topic were posted within an hour of each other.

I've merged the two together.
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