is radiation box in HFSS more like a receive antenna?
In real world scenario, what is the method to measure power radiated from an antenna? Isn't it to have a receive antenna in the far field or even the near field?
Thanks.
It does not act as a single antenna, but provides a surface on which the electric field may be determined in a number of tetrahedrals. The size of the tetrahedrals should be less than lambda/6. Since the distance from an antenna is typically a quarter wave, for most antennas this is going to be in the near field. I guess the far field pattern is computed via a Fourier transform of the near field, but I might be wrong on this.
Well, if you wanted to find the total power radiated, you could do it with an antenna in the far field. But it would not be easy, as you would need to sample all 4 pi steradians of solid angle and also use two different polarisations of antenna, since the polarisation of most antennas is not fixed for all anglesof radiation.
One is generally more interested in the radiation over a single plane, or a few characteristics of the radiation pattern, not the complete pattern to compute the power radiated. But there's no reason one would not want what you ask. If you can reasonably assume the antenna is lossless, then the radiated power issimply the power absorbed by the antenna.
Yes, one can compute the properties of an antenna from a near field probe. It's a lot more complex than doing it in the far-field, but is more practical some times.
Dave