Wednesday, February 16, 2011

Aiming a Yagi Antenna

Aiming a Yagi Antenna

The reason that so many manufactures and retail outlets sell Cellular Repeater systems with Omni antennas is because either they don't think that the consumer can handle pointing the Yagi or because they do not want to take the time to explain the process of aiming the antenna.

First we will look at why a Yagi antenna is a better choice in most situations. Then I will discuss the proper way to determine what direction to aim your antenna to optimize your repeater system.

To understand the reason for a Yagi verses an Omni we need to understand the differences between how an Omni and a Yagi deal with signal. An Omni is designed to receive signal equally from all directions. This may sound advantageous and it definitely makes installation easy. However……..

In this map you will see that the stick pin (our building) is almost equally spaced between three signal sources. With an Omni antenna placed on your roof top your cellular device would constantly have to choose which tower it wants to connect to. This will cause your signal to fluctuate and your call may be dropped because the network can not handle all the switching back and forth.

You might be thinking well if this is a problem, why wouldn't the cell phones have these problems? The simple answer is that your body acts like a shield and helps reduce the signal from some of the towers. That is why some times you can be talking and turn and drop a call.

Using a Yagi on your roof top will help eliminate this issue because a Yagi is able to isolate the signal to one tower and eliminate or greatly reduce the signal from the others.

Now back to the topic.

Aiming your Yagi requires several extra steps to help determine were to place the antenna and what direction to point it. (Mounting the antenna is covered here)

First you need to get signal readings from around the outside of your building and on the roof top. Most cellular providers have phones that can be put in to test mode, this allows you to obtain numeric signal readings that are far more accurate than bars. You can check the list here to see if your phone can be put in to test mode. If for some reason you can not put your phone in to test mode you will have to use bars on your phone to determine your signal. This is not nearly as accurate but it will work if you don't have any other way.

In this graphic you will see the locations that you need to take your readings. All readings will be portrayed as a negative number, a -103 is very bad signal and a -60 would be extremely good signal. Most phones show full bars at about a -85 or better.

By taking the readings this way, you use the building as a shield and this helps you determine the direction of the closest tower for your cellular provider. (This is the only way other than using a $10,000.00 spectrum analyzer to figure out what direction the tower is that you get the best signal from.) While taking readings from each side you should also make a phone call and than take a reading after the call again just to make sure the reading is accurate.

Many times I have been told by a customer that they know exactly were their closest tower is but when they perform this task they find out that the tower they are getting their signal from is in a different direction. This step will save a tremendous amount of time in the long run.

Once this process is completed you can start the installation. I will be covered the installation process in one of our future blog posts. For details on mounting the Yagi visit,"Installing a Yagi here ".

If you have any other questions regarding Yagi antennas or cellular repeaters please visit or call 1877-233-6673 and we will be happy to assist you.

Jay Nelson

Technical support

Cellular Solutions

Tuesday, February 1, 2011

Installing a Yagi Antenna

Installing a Yagi Antenna

Yagi antennas are a directional antenna. Most people are most familiar with the old TV antennas that were mounted outside on the roof of a home. This is a Yagi style antenna. The name Yagi refers to the designer that came up with this design or style of antenna.

This is a typical Yagi TV antenna (shown for reference only it will not work for cellular reception)

A Yagi antenna has many advantages over an Omni antenna. But it will take a little more work to install.

From this point we will be discussing Yagi antennas that are specifically for the Cellular frequencies and PCS frequencies.

These are examples of different style/frequency Yagi antennas

First we need to discuss polarization of the signal. The first picture is of a TV antenna mounted to a pole in a horizontal position this means that the receiving elements of the antenna are horizontal to the ground. With a cellular Yagi antenna the polarization needs to be vertical. This means that the elements that attach to the boom of the antenna will be vertically mounted.

Some times the Yagi antenna is encased in plastic cover this is to protect the antenna from the weather and to make it more aesthetically pleasing. Below you will find examples of this style antenna mounted to a pole. I also removed the plastic covering to show why the antenna needs to be mounted in this fashion and the last picture is an example of what not to do.

This is an example of a properly mounted antenna. As you can see from the second picture the narrow end is the end that will be pointed in the direction of your best signal for your cellular provider.

This is an example of how not to install a Yagi antenna to a pole.

Now lets discuss were to mount the pole and antenna on your building. Because this style antenna receives signal from the narrow end and rejects signal from the wide end the antenna will need to be placed on the outside of the home as high as possible an the side that has the best signal. You do not want the antenna mounted for example on the back of the home but be pointed across the roof of the home.

This is an example of a properly mounted antenna.

This is an example of a Yagi antenna mounted on the wrong side of a building pointed across the roof.

Cellular Solutions

Technical Support

Jay Nelson