Since I haven't seen any discussion on this topic (or maybe I just missed it) I'm wondering if everyone is using vertical and hasn't considered running horizontal. I currently am using a slotted waveguide Omni which radiates horizontal polarization. However I am likely to change to using two or more sector style antennas. I am thinking of continuing with horizontal but am interested in listening to reasons why not.

Regards

David ZL4DK

The only "why not" I can think of is "vertical omni's are cheap" 

When peole ask me I usually suggest "horizontal, or better yet dual(H+V) polarity" for their antenna setup. A sector setup is also  on my recommended items list as it allows you to reduce thenaount of RF hitting a single node.

I do hear a lot of users going with OMNI and I suspect they are  often vertical because the price factor not looking at all the advantages of getting out of the vertical clutter.

My suggestion list:

H+V followed by H and lastly followed by V polarity 

Circular may have advantages but antennas are hard to come by. X polarity also has less antennas and if I understand their polarity correctly seem like they only have an advantage where both H and V have a high noise level and you to be between the two.

Thanks. You kind of confirmed my thoughts. Yes I expect there to be a bit more vertical clutter than horizontal. I will stick with horizontal here for the time being. I might try building something like www.qsl.net/yu1aw/ANT_VHF/quados_antennas.htm and see how they perform. I'm only using Linksys radios at the moment. I'm finding the power fairly low. Currently running a link to another station 2.4km away not quite 100%LQ partly due to some trees in the Fresnel zone. Might keep trying different antennas and see how it changes things. Regards David ZL4DK

Given that the WRT devices have two removable antennae, would it be worthwhile to connect two yagis, one Horizontally polarized and and one Vertically polarized to create a circular pattern? What would be the minimum/optimum/maximum separation distance between the two beams and/or the cable length(s) feeding them? What net increase in gain and link reliability would I likely expect?

Would it be worthwhile to connect two yagis, one Horizontally polarized and and one Vertically polarized to create a circular pattern?

That's not how diversity works (please see the top of page 8 of WNDW - Chapter 10). If you wanted to create a simple circularly polarized pattern (many different types), you could use one antenna port, then split the signal to go to the two antennas. One of the feedlines in the splitoff would have to be a half-wavelength longer or shorter than the length of the other feedline.

Would be the minimum/optimum/maximum separation distance between the two beams and/or the cable length(s) feeding them??

Per mention above, both the Yagi antennas would be on the same beam with one vertical and the other Horizontal.

What net increase in gain and link reliability would I likely expect?

I do not know as there is no single right answer. One of the above links should have your answer (antenna dependent).

I will note that using one horizontal and one vertical would create an H+V dual polarity setup.

This is part of what helps the Ubiquiti devices, the Nanostations have a built in H+V dual polarity patch antenna. The Rocket is same where it has two ports and is intended to be used with a dual polarity antenna (sector or dish most common)

This is how the Linksys devices were intended to work originally as well, though they usually used antennas at at alternate 45's creating a pattern similar to a cross polarized X pattern it was still a dual input/output system with different  paths of signal allowing for better coverage.

Thanks Paul, the wndw.net site and their manual are a great resource. I have some reading to do :)

What do you all normally do with the un-needed second antenna socket on a WRT54?

I was also wondering what to do with the extra antenna connection.

The video at http://www.broadband-hamnet.org/documentation/146-hsmm-mesh-details-at-hamcomm-2011.html shows a WRT-type router with what appears to be two different antennae plugged in. One is directional and the other omni-directional. The speaker says that nearby stations can connect through the omni-directional antenna and the directional antenna is pointed toward a somewhat distant convention center where a lot of other stations are located, and that this allows stations near this thing to connect to the rest of the network that is too far away for them. It starts at 0:23 and the picture of the antenna connections are at about 1:28.