method of measuring antenna array in anechoic chamber using one element

[yefj]

Hello, there is a thing I heard that in anechoic chamber we cant do an accurate measurement of an array radiation patten because we are limited to a certain sample rate in an angle.
Why is that? what is the difference in measuring a regular antenna to a antenna array i anechoic chamber?
Why we would get an innacurate pattern due to the sample rate of the rotating test antenna?

The solution to this problem is testing only one element and make radiation pattern of the array using a radiation pattern of a singl element.
How can we build radiotion pattern of an array using radiation pattern from a single pattern?
Thanks.

 

[biff44]

i am no antenna guy, but i believe the antenna you are trying to measure is "electrically large", and the anechoic chamber is physically small, so you are only measuring the radiation pattern of "the near field". If you put that same antenna outdoors, and measured it again in the "far field" you would see a big difference in the two patterns measured.

Some antenna guys are able to do a conformal transform to convert the measured near field into a reasonable facsimile of the predicted far field pattern, but there are limitations that may have to be imposed on how the measurement is done.

 

[vfone]

The antenna pattern of individual elements of a phased array antenna, is very important forming the array antenna pattern. But the most important things getting the desired array pattern, are the elements spacing and phasing.
You can have the best element pattern, but if the array is not well designed you get a poor array pattern, with many unwanted grating lobes.