V&H being swapped will always cost you at least 20 dB and if you have them precisely aligned V&H I can see where 40 dB is reasonable.
From: Ken Hohhof Sent: Friday, March 6, 2020 10:18 AM To: 'AnimalFarm Microwave Users Group' Subject: Re: [AFMUG] PTP Microwave antenna question OK, that says the antenna should be dual pol capable. So … is a puzzlement. You’d expect a problem would cost a few dB, not 40 dB. Unless H & V were swapped. Sounds like Cambium is looking into it, maybe they come up with some ideas. From: AF <af-boun...@af.afmug.com> On Behalf Of Mark Radabaugh Sent: Friday, March 6, 2020 11:00 AM To: AnimalFarm Microwave Users Group <af@af.afmug.com> Subject: Re: [AFMUG] PTP Microwave antenna question It’s currently 2 single pol Horizons on a Dragonwave OMT mount that combines the H&V to the round waveguide on the back of the antenna. Mark Radabaugh Amplex 22690 Pemberville Rd Luckey, OH 43443 419-261-5996 On Mar 6, 2020, at 11:19 AM, Ken Hohhof <af...@kwisp.com> wrote: We put 11 GHz 820C w/XPIC on existing Trango 3 ft dishes replacing single pol ApexPlus ODUs and everything went as expected. I’d have to look up the details but I think it worked because Trango used Remec circular even with single pol except for 6 GHz. We should have adjusted for best XPIC cancellation but instead we just made sure the ODUs were plumb. But I think what we did was roughly the same as what you’re doing, so it should work. We got a couple bad 820S radios last year, failed the RF loopback test, but it sounds like you have pretty thoroughly verified it’s not bad radios. Were the Dragonwaves single or dual pol? From: AF <af-boun...@af.afmug.com> On Behalf Of Mark Radabaugh Sent: Friday, March 6, 2020 9:37 AM To: AnimalFarm Microwave Users Group <af@af.afmug.com> Subject: [AFMUG] PTP Microwave antenna question We have installed a lot of Cambium 820C radios without much trouble. Yes, the configuration takes some getting used to but we probably have 46 links working and installed, so it’s not like it’s our first rodeo configuring these things. And then we tried something new - reusing a 4’ Andrew Dragonwave antenna in a XPIC configuration. We purchased the Cambium adapter plate that clips onto the antenna radio mount and presents the 820C mount for the OMT. Take off the dual Horizon radio OMT, add the 820C and the RF signal is shit - in the -80’s from the mid 40’s. Reverse the process and put the Horizon’s back on and the signal is fine. So we thought we had a bad 820C. It’s happened before. So we take two different sets of 820C’s and test them one at a time swapping them in for known good installed radios on working links. The 820C’s are fine. Okay… we forgot to test the OMT's when we did that. So we try the OMT’s in the shop - and they work fine. At this point the only thing left is the antennas themselves and the adapter plate. The adapter plate is nothing more than a hole in a aluminum bushing with a couple of small steps to match diameter between the OMT and the antenna waveguide. Pretty hard to screw up. We have a pair of Dragonwave antenna’s in the shop that we can mount all of this to and try here - and we can’t get a decent signal even 20’ apart. I’m at a loss at this point. The only part that doesn’t appear to work is the adapter plate - and there is nothing interesting about it. How the heck can this not work: <image001.jpg> <image002.jpg> I can’t buy that the alignment of the antenna would need to be adjusted. That makes no sense in my head. Am I wrong in that assumption? Mark -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com -------------------------------------------------------------------------------- -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
-- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
