It's interesting that the dish itself appears to be exactly the same as the ePMP Force 200, but the feedhorn is shaped significantly differently (I'm assuming because they needed to fit more electronics inside it). I've never noticed the Force 200's underperforming... I don't know how they compare to an SM+reflector setup, but I've swapped between Force 200's and various connectorized dishes, as well as Ubiquiti radios, and the signal levels have always been pretty much inline with what I expected.
Also interesting is that on the new ePMP Force 300 they changed to a design where the radio is sits behind the dish instead of being completely inside the feedhorn (it's still attached to the feedhorn, but it goes in from the back) ... I wonder if that's because of problems with the 450. On Thu, Mar 28, 2019 at 4:20 PM <ch...@wbmfg.com> wrote: > A 17.5” reflector with a good feed should have about 26 dBi. > > *From:* Ken Hohhof > *Sent:* Thursday, March 28, 2019 3:08 PM > *To:* 'AnimalFarm Microwave Users Group' > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > It’s around 18.5 inches but the actual reflector part is 17.5 inches, with > a 0.5 inch flat area all around the edge. > > > > *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *ch...@wbmfg.com > *Sent:* Thursday, March 28, 2019 2:43 PM > *To:* 'AnimalFarm Microwave Users Group' <af@af.afmug.com> > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > > Thanks, that helped a bunch. It is like a Rocket. > > Could be over illumination, under illumination or just too small of a > reflector for the gain. > > What is the diameter of the reflector? Looks like it is about 20 inches > or so. > > > > Someone take a hammer and break open the feed and snap a photo for me.... > save the pieces so you can glue it back together later... > > > > *From:* Ken Hohhof > > *Sent:* Thursday, March 28, 2019 1:26 PM > > *To:* 'AnimalFarm Microwave Users Group' > > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > > I’m busy configuring a licensed link or I’d snap a photo. But here’s a > Cambium video of assembling a 450b high gain, maybe you can glean enough > from this. Note that there is an optional radome that snaps onto the front > of the dish, they don’t show it in the video, but some of us like the > radomes for aesthetics/windload/snow. > > > > https://www.youtube.com/watch?v=z88P-0nZkZ8&feature=youtu.be > > > > > > *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *ch...@wbmfg.com > *Sent:* Thursday, March 28, 2019 1:54 PM > *To:* 'AnimalFarm Microwave Users Group' <af@af.afmug.com> > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > > Yes, I could probably google it, but I would like to have an image of the > SM and reflector or whatever that is underperforming. > > > > *From:* Ken Hohhof > > *Sent:* Thursday, March 28, 2019 12:17 PM > > *To:* 'AnimalFarm Microwave Users Group' > > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > > I think he meant a photo of a Cambium 450b, or something relevant to > improving the antenna performance thereof. > > > > What were you thinking the topic was about? > > > > > > *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Carl Peterson > *Sent:* Thursday, March 28, 2019 1:05 PM > *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> > *Subject:* Re: [AFMUG] [*] Re: [*] corrective optics > > > > "What would you like to see?" > > > > I'm OK with the spam, but if this thread goes the wrong way I might need > to unsubscribe. No offense, just not my bag. > > > > On Thu, Mar 28, 2019 at 11:06 AM Mark Radabaugh <m...@amplex.net> wrote: > > What would you like to see? > > Mark > > > On Mar 28, 2019, at 10:26 AM, Chuck McCown <ch...@wbmfg.com> wrote: > > 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 > > -- > 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 > > > > > -- > > Carl Peterson > > *PORT NETWORKS* > > 401 E Pratt St, Ste 2553 > > Baltimore, MD 21202 > > (410) 637-3707 > ------------------------------ > > -- > 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 > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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