Antenna Anechoic Chamber-correct position while measuring

Hello

I have an important doubt about how to measure with an Anechoic Chamber. My question has to do about where to place the antenna under test (AUT).
Having an anechoic chamber: there is a broad band antenna in the side wall, in front of this antenna, in the Chamber, we have to position our AUT. This AUT has to be aligned, but how??

Imaging that we want to measure a square patch antenna feed by a microstrip line in the middle of one of its sides. This is our AUT. We want to measure it in the Anechoic chamber.

How should be placed? The center of the squere patch should be the same as the center of the broadband horn antenna that will be use to measure?

I have found something about the center phase point. ¿Antennas should be centered at this point always? How can be defined this point?

I hope is clear enough
Thanks

Balanis mentions on this topic:

For practical antennas such as arrays, reflectors, and others, a single unique phase center valid for all values of θ and φ does not exist.

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For the patch, I would expect it near the feed point, or somewhere between feed point and center. A standard distance for the measurement would be 3 m, does the difference actually count in this case?

I'm more interested in measuring a single antenna, by the moment. My doubt is about how to place it in two planes, perperdicular to the floor and paralle to the broad band antenna. I'm always talking of a planar microstrip antenna.

What I thought is that the AUT antenna should be centered where the maximum E field appear with the broad band antenna center. But I'm not sure. Any information, link, etc, will be very helpfull.

I'm more interested in measuring a single antenna.

Click to expand...

I know. Balanis comment applies for a single patch antenna as well. Only antennas with simple symmetry have an obvious phase center, e.g a dipole. You didn't mention the antenna dimensions, but I answered the question for the time being, I think. In one direction, the phase center is obvious by the antenna's symmetry, shifting it along the other direction until you achieve minimum group delay to the receiver (requires a VNA) would be an empirical methode to evaluate the phase center.

You also may want to rotate the antenna to get the directional charateristic.