Hi Matt, is this a new change? As one of our early PMP450 2.4ghz deployments had very low linktest performance even with perfect signals, which I traced to the non-Cambium AP antennas we had installed being mislabeled V+H models instead of dual-slant, with the resulting cross-polarity signal mashup resulting in the radios falling to MIMO-A mode.
On Fri, Dec 4, 2015 at 3:29 PM, Matt Mangriotis < [email protected]> wrote: > Just want to point out that this same logic and coding exists in the PMP > 450 platform as well. > > > > You’ll see very soon when we release the *high gain integrated* *PMP 450 > SM at 3 GHz*, it’s H+V, not dual slant, but works equally as well and > gives you 19 dBi gain. > > > > Matt > > > > *From:* Af [mailto:[email protected]] *On Behalf Of *Faisal Imtiaz > *Sent:* Friday, December 04, 2015 3:25 PM > *To:* [email protected] > *Subject:* Re: [AFMUG] to slant, or not to slant - that is the question > > > > Since inquiring minds want to know... > > > > Here is the Word on this topic from Cambium... (While this was titled > 2.4Ghz, as per them, it applies to their 5ghz as well). > > > > :) > > > > Faisal Imtiaz > Snappy Internet & Telecom > 7266 SW 48 Street > Miami, FL 33155 > Tel: 305 663 5518 x 232 > > Help-desk: (305)663-5518 Option 2 or Email: [email protected] > > > ------------------------------ > > *From: *"Joshaven Mailing Lists" <[email protected]> > *To: *[email protected] > *Sent: *Friday, December 4, 2015 4:15:55 PM > *Subject: *Re: [AFMUG] to slant, or not to slant - that is the question > > The Atheros chipset differentiating between the Mimo chains does not have > to do with 45º slant vs 90º… it means that chain A and B on one radio can > be H&V or V&H while chain A and B on the other can be H&V or V&H > interchangeably with no loss because and the chip will just cross them over > as needed. This means that hooking up the antenna cables “backwards” won’t > effect anything. It doesn’t mean that the orientation of the antenna is > irrelevant. > > > > The energy received by an antenna that is out of phase with another > antenna is much less then if it was in phase that is a principal of radio > that no chipset will ever overcome. Now… maybe you can make a magic > antenna that is “multi phased” such that it can tune in a 45º phase offset > signal well. I suspect that the Cambium equipment when properly matched > will both have the same polorization. > > > > I believe that if your having the same outcome on slant or not slant it > would be due to one chain being refracted. For example if your horizontal > chain was fine but the virtual chain was refracted off something such that > the wave was on or near a 45º slant then you would have the same basic > performance regardless of a standard or slant orientation. This however is > a path issue not a design characteristic of the chipset or antenna. > > > > FYI, linearly polarization is not a reference to the polarization being on > a vertical, horizontal or slant axis but a reference to the way the wave > propagates, circular polarization is an alternative to linear polarization > not “slant". > > > > > > > > Sincerely, > > Joshaven Potter > MTCNA, MTCRE, MTCWE, MTCTCE, UACA > Google Hangouts: [email protected] > Cell & SMS: 1-517-607-9370 > > [email protected] > > > > > > > > On Dec 4, 2015, at 2:13 PM, Adam Moffett <[email protected]> wrote: > > > > The DSP in the ePMP can do some kind of processing to correct for the 45 > degree offset when you have slant on one end and V+H on the other. I might > not be stating it with the correct technical jargon, but that's the gist of > it. They sell a dual slant sector for the AP with the intent to use it > with V+H integrated SM. > > This is a built in feature of the Atheros chipset, so presumably UBNT > radios can do the same thing. > > That all said...I would try to match them up as just a matter of > principle. > > > On 12/4/2015 2:07 PM, Joshaven Mailing Lists wrote: > > Your AP & SM should always have the same antenna orientation. I promise > you that you don’t want slant on the AP and not on the CPE. If the signal > is so obstructed that the orientation is screwed up to the point that > unmatched polarization is actually a benefit then there is something > seriously wrong… > > > > > > Sincerely, > > Joshaven Potter > MTCNA, MTCRE, MTCWE, MTCTCE, UACA > Google Hangouts: [email protected] > Cell & SMS: 1-517-607-9370 > > [email protected] > > > > > > > > On Dec 4, 2015, at 1:59 PM, Paul McCall <[email protected]> wrote: > > > > > > We are looking at smaller sector sizes for a 5 Ghz ePMP cluster (60 degree > probably), and am considering my options, which might also increase my gain > quite a bit. Using a non-Dual Slant sector such as AM-5AC21-60, would > increase my options. There have been a calling threads on Cambium’s sites > about whether Dual Slant was a big factor at the AP if the SMs aren’t > dual-slant. > > > > Cambium’s Daniel Sullivan made this comment … The thread was originally > about 2.4 Ghz options, so not sure if it applies exactly to 5 Ghz. > > > > Paul > > > > > > > > > >
