Free space vs anechoic chamber

hello all,

I want to test antennas at around 5 to 10 GHz. Which is better free space or anechoic chamber?Could you please give references?

Thanks in advance.

If you have anechoic chamber, it is better. If you don't, free space is better.

It is hard to beat the real world of outdoor testing for real data! However, to get into the far field, the antennas have to be spaced far apart, and you would prefer them to be high off the ground.

If you can not do that, then an anechoic chamber is acceptable. You want it to be "anechoic" at your frequency of interest, and once again you want it long enough to be in the antenna's "far field". If it is not long enough, there are "compact" ranges that use lenses or other means to simulate being in the far field. But these are all approximations to being outdoors, not reflections, in the actual far field!

Have you actually done antenna measurements outdoor in the 5-10GHz range?

I have, and found that a pain because you have lots of reflections from your environment. The option to put the antennas high up on a tower is only a theoretical solution at these frequencies. I switched to the anechoic chamber, which was easier to do and more accurate.

All is relative. If you have some antenna gain and the antennas are 30' in the air, it should not be much of a problem. If you are a few feet off the ground, yes you may have reflections. It also depends on what you are measuring...a simple antenna gain vs angle test is easy, but sidelobe testing with 40 dB nulls are going to be a challenge anywhere!.