What would you like to see? Mark
> On Mar 28, 2019, at 10:26 AM, Chuck McCown <[email protected]> wrote: > > How about some photos. > > Sent from my iPhone > >> On Mar 28, 2019, at 6:58 AM, Ken Hohhof <[email protected]> wrote: >> >> If you ever do the experiment again, it would be interesting to rotate the >> antenna to see if there’s some kind of sidelobe pointed toward the ground or >> something. Obviously you can’t install it rotated or upside down (unless >> you really trust that cable gland to seal against rain), but it would be >> interesting to see the results. Like you said, maybe some component in the >> feed horn is blocking the RF. >> >> Cambium is in a better position to investigate this, it’s disappointing if >> they aren’t taking it seriously. >> >> >> From: AF <[email protected]> On Behalf Of Mark Radabaugh >> Sent: Thursday, March 28, 2019 6:19 AM >> To: AnimalFarm Microwave Users Group <[email protected]> >> Subject: Re: [AFMUG] [*] corrective optics >> >> >> >> >> On Mar 27, 2019, at 10:11 PM, Ken Hohhof <[email protected]> wrote: >> >> In another thread, Mark Radabaugh posted: >> >> “For your next product…. Corrective optics for 450B high gain CPE!” >> >> Mark, I’m not sure if you were serious, I suspect yes. >> >> >> Yes - but I’m not sure what is possible with the design. >> >> >> >> I know it’s frustrating that the antenna gain is lower than the old >> reflector dish, Cambium dropped the number on the spec sheet to 24 dBi, but >> I think even that is optimistic, I think it’s about 2 dB less than the old >> combo which was supposed to be 25 dBi. Lower antenna gain is going the >> wrong way! I don’t care if it does have higher xmt power, that does nothing >> for the downstream direction. >> >> >> Changing the spec sheet to match what they ended up with was a pretty big >> cop out when the product failed to meet design expectations. >> >> >> >> In calling for corrective optics, do you have any info or even a gut feel >> for whether the problem is in the feed or the dish? Is it as simple as the >> dish is just too small? >> >> >> I suspect that they managed to block part of the antenna feed horn with >> other components. >> >> >> >> >> Also, is it just the gain is low, or does the 450b hi gain have other >> issues? Like poor F/B or sidelobe performance or something? >> >> It seems like if the 450b high gain is far away from other surfaces it works >> mostly to spec but when mounted in the typical locations near rooftops it >> seems like it either picks up more destructive multipath interference than >> previous designs or the antenna pattern distorts badly. For a long time I >> thought they didn’t manage to get the feedhorn in the focus of the dish but >> Cambium assures me that it’s right. We are seeing decent performance under >> 5 miles but it seems to fall apart much quicker over 5 miles than would be >> expected. >> >> We set up a test with the bucket truck and drove it out and measured every >> mile to 10 and it came back fine - but that was 50’ in the air with nothing >> around. Yet swapping out standard 450 SM’s with beehive or KP dishes with >> 450B’s at >5 miles routinely fails with poor signal. The difference is >> often far more than the 2dB the spec sheets would indicate. Sometimes it >> works if the antenna is well away from all other surfaces like on a tower >> but for the majority of installs the swap fails. Why were we doing that >> anyway? We wanted to start using 5.1/5.2. >> >> >> >> I know the 450b mid-gain is frustrating because apparently Cambium doesn’t >> think a tight vertical pattern is important. I keep wondering if a top and >> bottom flap like on the old 2.4 Stingers would correct that. >> >> Cambium seems to be sharing antenna designs between ePMP and 450, so the >> same issues probably exist in the corresponding ePMP products. >> -- >> AF mailing list >> [email protected] >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> [email protected] >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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