How about some photos. Sent from my iPhone
> On Mar 28, 2019, at 6:58 AM, Ken Hohhof <af...@kwisp.com> 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 <af-boun...@af.afmug.com> On Behalf Of Mark Radabaugh > Sent: Thursday, March 28, 2019 6:19 AM > To: AnimalFarm Microwave Users Group <af@af.afmug.com> > Subject: Re: [AFMUG] [*] corrective optics > > > > > On Mar 27, 2019, at 10:11 PM, Ken Hohhof <af...@kwisp.com> 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 > 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
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