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Old 14 February 2017, 22:39
Akheloce Akheloce is offline
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Join Date: Sep 2012
Location: Alaska
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Anyone ever played with millimeter wave?

At work, I'm testing out a 2.5Gb 80Ghz point to point shot at 4700 meters. My math says I should have an optimum RSSI of -44dB, and the manufacturer agrees. Aligning it, I'm seeing the secondary and tertiary lobes clearly on the meter with peaks of -66 and valleys of -90. I get what I believe to be the primary lobe, and still get -56 on one end, and -65 on the other. I feel pretty confident that I'm on the center lobe on both ends based on my meter readings, but I could be fouled up.

I've aligned standard microwave and lasers plenty of times, and have not had this much trouble, primarily since the RSSI's are linear with both of those methods.

Anyone have any specific field experience with these that can offer some pointers?
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Old 15 February 2017, 07:59
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mdavid mdavid is offline
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Location: High Springs, FL
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No specific experience but as a general ham licensee I'm very intrigued by what you're setting up.
I'd love to read more details as you sort through these issues.
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Old 15 February 2017, 13:33
Akheloce Akheloce is offline
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Join Date: Sep 2012
Location: Alaska
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Weather is crap today, and I have other things on my plate, so I'm not going to mess with it today.

The gist of the system is 2 12" round antennas which are on an adjustable gimble attached to a 4" pole on the roof of 2 of our facilities. They are capable of 2.5Gb total, with 2 sfp inputs and 2 cat 5 inputs. It's powered via POE. My intent is to run 2x 1Gb LAG/LACP to feed a DLC in a remote area. Once I get it aligned properly, I have a pair of RFC-2544 test units on each end to flog the circuit for a few days.

The beam of the center lobe is approximately 7mm in diameter, so at 3 miles, it's quite the pain to align... in February... in Alaska. Rough geometry figures each degree of angle = 350'. To make it more interesting are the side lobes. There are at least 2 lobes on either side of the primary that I've identified so far. This makes alignment harder since as you're adjusting based on signal strength, you might find out that you're on a side lobe, and have to start all over again. AESA/SAR would be a lot easier :). Talking to the manufacturer, I asked about a doppler shift/ GUI based alignment tool in software, and he said they're working on it.
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