5GHz PMP 450 Antenna Polarization

Hi,

What is the main reason vertical-horizontal antenna polarization is used on the 5GHz PMP 450 as opposed to dual slant (+/- 45deg) on the 2.4 and 3 GHz 450?

We have a discussion in this point but i didnt find any answer in the doucments from Cambium!

Thnx

Mohammed

Just up until a year or so ago, it was nearly impossible to find dual-pol 5ghz antennas that were anything but H+V. Cambium wanted to make it easy for their AP's to use 3rd party antennas and maintain compatibility with the integrated antennas in their SM's, so they stuck with what was easiest for everyone to get.... H+V pol antennas.

As far as 3.Xghz is concerned, the vast majority of antennas for this band are +-45 degrees. The cellular/carrier manufacturers primarily use dual-slant for their antennas and 3.5 is designated as an LTE band. It's very very easy to find 3.Xghz dual-slant antennas... it's very difficult to find H+V antennas. Again, Cambium wanted to make it easy for their AP's to use 3rd party antennas and maintain compatibility with the integrated antennas in their SM's. There's also some minor RF propagation benefits for using +-45 degrees as well that's more relevant to celluar opeartors in urban environments with multipath.

And lastly, the 2.4ghz antennas are kind of a toss up... many of them are H+V, but almost all of the wide band ones that cover 2.3-2.7 are +-45 degrees... again, because of the cellular/carrier market. There's also some minor RF benefits to using dual-slant when everyone else is using H+V... it's like a 3dB rejection on each pol over H+V. In this instance, Cambium wanted to give their radios a little bump in RF performance against all the H+V antennas out there, along with preference for the assumed higher quality antennas that typically are sourced when you buy cellular/carrier grade antennas. Buying better antennas allows for better front to back ratios and allows for better collocation of multiple radios at site when using GPS sync and back to back frequency reuse.

Lastly, Cambium wrote an extensive white paper on how/why you can use H+V pol antennas with +-45 pol antennas for AP's and SM's or vise versa. I've attached for your review. There's also a good thread that discusses this HERE.

Another reason on 2.4 GHz, was a mechanical size constraint... an H+V patch antenna would not have fit into the SM housing that we're using.