Omni-directional Antenna

What does omni-directional mean?

Omni means all, or every. So omni-directional means that the antenna sends information in every direction.

What does the antenna do?

Omni-directional antennas are used in many applications, but until Nomad, they were the only way a moving robot could send information. Nomad uses an omni-directional antenna to send and recieve low level communications, such as commands. It cannot use this antenna to send complex pictures from the panospheric camera because it cannot send enough information quickly enough with it. But the omni-directional antenna is still the robots main communication for basic tasks.

Think of it like this...

An omni-directional antenna broadcasts in all directions, outward from the antenna, so only one part of the signal reaches the reciever, the rest is just sent out into space. The concept is easy to understand if you use a picture of a fountain as an example. In the picture to the right you can see how the water is spraying in many different directions.

Image taken from http://www.kcfountains.com

Compare this to the picture of the waterslide on the left. All of the water in this picture is all falling inthe same direction, so the stream of water is larger and stronger.

Want to see how it works? Try it yourself...

Next time you're in the bathtub try this:

First, run the water and put your hand under the faucet as close to the drain as possible.
Second, put one hand under the faucet again, but this time place it right under the faucet to the water sprays out in all directions. Put your other hand someplace where the spray is hitting it.

Pretend that every drop of water from the faucet is a piece of information, just like the kind of information that the omni-directional antenna would receive. Which time did more information reach your hand? If you aren't sure, just think about which time your hand got more wet.

When you made the water spray, you were actually seeing how the omni-directional antenna works. If the information is sent out in more directions, less information will reach the receiver.

Back to Home Page

Animated waterslide image taken from TODAY magazine

Last Modified on: Thu Jun 12, 1997