What kind of antenna is this?

Question

http://flickr.com/photos/bobseditsuite/2738094147/sizes/l/

And why would it be tied into my two Dish Network antennas?

This rig is on the roof of my office building. We're trying to solve some cell phone reception issues. The contractor couldn't figure it out and left it in "as is" condition. I'm trying to figure out what everything is.

Thanks in advance.

Answer 1

I had a look at your photo; that's called an "off-air" or "over the air" antenna, depending on who you talk to.  Basically it's used to receive broadcasts from local television stations.  The signal is combined onto the same cable as that which is used for for the satellite signal; a demultiplexor is used at the television end to separate the satellite and normal television signals so you can watch either/or when you want to. That particular antenna would be suitable for local High Def stations if you have any in the direction it's pointed at.

Back to your question: I highly doubt this equipment is the cause of your cell phone reception issues. Reception issues are usually due to distance from the cell towers, building construction, blocked signal from other stuctures, intereference from "noisy" equipment like industrial motors etc.

Answer 2

That's a Yagi antenna, looks to be for UHF band television based on the size of it, most likely. That would be used to receive over-the-air (eg, OTA, broadcast, etc) television in addition to your Dish Network satellite service. Most of the recent Dish Network STBs have OTA tuners, and OTA has gained in popularity since HDTV broadcasts began, since broadcast HDTV is of very high quality, where you can get it.

Given the use of the Yagi, which is a fairly high gain, directional antenna, you may be out the suburbs or even "the boondocks", a term that pretty much describes my demesnes. Your cell phone troubles are likely as not based on the distance to the cell tower, not any interference. As a receiver, that antenna doesn't actually create any interference. Some cell phone services in the USA operate at around 850MHz, which might be more or less in the upper range of that antenna, but that doesn't affect your ability to hit the cell tower. In more populated areas, they run cells at 1900MHz, which is even less of an issue.

However, both 850MHz and 1900MHz frequencies have issues with buildings, trees, etc... particularly the latter band. There are no natural sources of interference at those high frequencies, and even man-made stuff is not a direct issue, though any loud enough source of RF can cause interference just on the basis of overwhelming your phones' receiver circuits.

If you get better cell phone performance outside your office building than inside, that's a good sign it's just building-based attenuation. You might look at getting a repeater in the building, and mounting a cellular antenna on the roof. Here are a couple of companies that sell these:

http://www.repeaterstore.com/

http://www.unwiredsignal.com/default.asp...

http://cellularsolutions.com/

There are a couple of sites that let you find the cell towers close to where you are. This may also help:

http://www.antennasearch.com/

http://www.cellreception.com/towers/