Spoiler alert: The slotted extrusion looks like a waveguide but in reality it is more of a square coax. There is a center conductor running up the middle and it is either shorted or open at the end. Generally it is printed on a PCB rather than a wire but either will work.
That sets up standing waves along the center conductor where the peaks coincide with the horizontal steps in the slots. The peak of the standing wave excites a current on the slot. The slot current then runs up and down the vertical parts of the slot. A vertical slot radiates in a horizontal polarization. So that is the H pol part. The circuit boards on the sides are a series fed array of patches. That is the V pol part. The V pol part helps to circularize the H pol part because those types of antennas have more of a peanut shaped pattern. The V pol is a bit less circular. From: Rory Conaway Sent: Friday, May 29, 2015 1:08 PM To: [email protected] Subject: Re: [AFMUG] Arc dual polarity omni I didn’t see the waveguides in the picture. That’s what made me curious. Rory From: Af [mailto:[email protected]] On Behalf Of Mathew Howard Sent: Friday, May 29, 2015 11:15 AM To: af Subject: Re: [AFMUG] Arc dual polarity omni In the interests of avoiding doing any real work, I opened up one of the Arc 13dbi 2.4ghz dual polarity omnis... it seems pretty similar to every other dual polarity omni I've seen, nothing like the 5ghz. On Fri, May 29, 2015 at 11:40 AM, Mathew Howard <[email protected]> wrote: We have several of the 2.4ghz version and they seem fine. I've done a little testing and the pattern seems pretty similar to the ubnt 13dbi dual polarity omnis - I've also replaced a few other kinds of omnis (mostly single polarity) with them and I didn't see any notable difference in coverage. I'm not sure why the 5ghz is so bad... On Fri, May 29, 2015 at 11:35 AM, Glen Waldrop <[email protected]> wrote: That is quite horrible. I've got the Arc 2.4GHz 13dBi omni serving 17 rural customers, no particularly strange issues like that, though now I'm thinking of testing more thoroughly. ----- Original Message ----- From: Mathew Howard To: af Sent: Friday, May 29, 2015 11:04 AM Subject: Re: [AFMUG] Arc dual polarity omni Yep, it is a triangle... the thing is the sectors appear to be about 15 degrees each. On Fri, May 29, 2015 at 10:55 AM, Chuck McCown <[email protected]> wrote: I presume there is a third array that we cannot see arranged in a triangle. This is essentially three sectors phased together. Our omni is much more of a true omni. From: Mathew Howard Sent: Friday, May 29, 2015 9:34 AM To: af Subject: [AFMUG] Arc dual polarity omni We have some ARC wireless 5ghz dual polarity omnis that I've suspected for awhile are under performing, so I finally got around to swapping one for sectors and found that was very much the case... connections pretty much all improved - some by as much as 15db. out of curiosity I did some further testing and found that by rotating the antenna the signal to a client about a mile away would change by close to 15db, with it only being good at a few pretty narrow points. So... I opened it up to see if there was an obvious reason it's so much worse than the other dual polarity omnis I've used, and it is indeed very different... I'm no antenna expert, but something seems very wrong with this design. Why would they even make something that works that poorly?
