We have been replacing a fair number of grids with panels for several reasons.  The first is ice in climates many of our clients operate.  The second is we have found water tends to penetrate the feedhorn [...]]]> J.J. has a good video over on his blog about grid antennas and Ice.  You can view the post here.

We have been replacing a fair number of grids with panels for several reasons.  The first is ice in climates many of our clients operate.  The second is we have found water tends to penetrate the feedhorn itself.  After a season or two the horn fills up and corrodes.  I have taken several “swishy” grids down with water dripping out of the feedhorn and neck.

http://www.appstorehq.com/wifialign-iphone-189338/app

Vertical Polarization (V-POL) is the most common out there.  Home routers and other [...]]]> WISPs have two major antenna polarizations to deal with. You have Horizontal & Vertical.  As with anything you have bonuses and drawback of each.  Some WISPs use Circular polarization but I would recommend against it.  Your choices on circular polarization are much more limited.

Vertical Polarization (V-POL) is the most common out there.  Home routers and other consumer hardware are almost always v-pol.  V-Pol is cheaper to manufacturer when it comes to omni-directional antennas especially.

Horizontal Polarization (H-POL) is used for situations where there is quite a bit of noise.  By switching from V-pol to H-pol in a high noise area you might gain 20+db of separation from noise.  This only works if there is not much horizontally polarized antennas out there.  H-pol is good for links over water due to the fact it spreads out left to right as opposed to up and down.  This way you do not get refraction and other such weirdness from the signal bouncing off the water.  H-pol antennas are typically more expensive to buy.

Panel and directional antennas are very easy to change polarization.  You simply rotate the antenna 90 degrees.  Most modern enclosure designs allow you to either re-locate the connectors for ethernet or to rotate the entire panel.

Some manufactures give you the ability to software select what type of polarization you want. Ubiquity is one such manufacturer. Within their software you can select your antenna polarization. This is extremely handy should you have both sets of antennas on a tower.

You have 3 major type of antennas you will deal with.

The first is the Omni directional.  This receives and transmits a full 360 degrees. In otherwords a single antenna can cover a full 360 degree radius. An Omni is not good [...]]]> If you don’t come away with anything else in this article remember this. Omnis are bad.

You have 3 major type of antennas you will deal with.

The first is the Omni directional.  This receives and transmits a full 360 degrees. In otherwords a single antenna can cover a full 360 degree radius. An Omni is not good for long distance links or high noise areas.  Because it transmits the full 360 degrees it also picks up noise and interference from 360 degrees.  An omni is best suited for a hotspot these days.

The second is the sector.  These come in several beamwidths. They are typically 60 degress all the way up to 180 degrees.  These are best for point to multi links.  This way you can “sectorize” the 360 degrees of coverage into smaller sections. By doing this you increase signal, increase capacity on your Access Points, and decrease the noise each sector hears.  For example, if you have 3 120 degree sectors (3×120=360) each sector will only hear 120 degrees of area.

The third is the point to point antenna.  I am grouping parabolics, grids, and anything under 60 degrees of beamwidth into this category. You will find these antennas as part of backhaul links for the most part.  They have low beamwidths and higher gains.

Our next antenna installment will be the type of polarization on these antennas.