An anechoic chamber is a room that is specifically designed to measure the radiation patterns of an antenna and to monitor electromagnetic interference. What is unique about this chamber is the fact that it has been electrically sealed and this helps to reduce the likelihood of external signals entering into the structure.
Walls are Sensitive
In the chamber, you will find walls that look like they are made of Styrofoam. These cones are actually carbon permeated, that is designed to absorb any radioactive waves that are in the room. While they are very powerful, they can fall apart with a single touch. Because of this, it is important that in this room, you do what you can to avoid any unnecessary contact with them.
Measurements in the Anechoic Chamber
In the room, you will begin to see how antenna radiation patterns normally form. What is important to note is that these antennas are going to send power more in direction than the others. This allows polarity to be measured, in addition to determining the grain, directivity and side lobe value of the patterns. Electromagnetic interference can also be tested.
Placement of the Antenna
Setting up the antenna isn’t too complicated for the AUT. Typically, it will be suspended in the air and then rotated. On the positioner at the base, will be a turret that will spin the theta along the base and the phi at the top. With everything properly placed where it belongs, testing can begin.
On the roll rotator, you will need to ensure that the SMA port is connected properly.
Depending on model you are using, there may be switches and button settings that need to be adhered to for proper operation. When it is powered up, you can then position the unit to ensure that it is aimed for an optimum reading.Collecting Data
When the system has been turned on, you will need to ensure that the basic settings are in place. A PC will usually be connected to the anechoic chamber and will have the software in place that is needed to obtain your readings. Most software requires listing multiple frequencies to scan and you will be able to test those frequencies.
You can then begin to work on the raster definition as you begin to rotate the antenna through the angle settings. You should keep in mind that as a rule, you will want to avoid measuring the back lobes, since there is a blockage to the plane wave in this area.
Using an anechoic chamber is going to be critical when determining key factors about an antenna. In this fragile structure, you need to be careful about how you handle key sections and how you place the antenna. Then when it comes to collecting data, you should know what you are looking for, for the best overall experience.
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