Slot antenna in SIW Air box distance

Hello to all the members of this great forum.

I have one question and i would like your knowledge about it.

I have designed a 6 slots antenna in 60 GHz using SIW technology, i have placed the radiation air box 1.5*λ away from slots, is this enough for reliable far-field results ,by assigning radiation as infinite sphere?

Thank you alot all of you for your time

hi.radiation box should be at least λ/4 away from radiation surface.

If you want to be sure of the accuracy of your simulation, the typical procedure is:
1. Simulate with a radiation surface at a distance of λ/4.
2. Increment distance to λ/2 and resimulate.
3. Check the difference between results, and depending on the required accuracy consider keeping λ/4 (usually), λ/2 (sometimes), or larger (almost never).

thx danieldani.but how to decide which simulating result is desire?

For example, let consider the case that you care about gain.
Simulation 1 with λ/4 radbox gives you 37.1dB of gain.
Simulation 2 with λ/2 radbox gives you 37.3dB of gain.

Therefore, simulation 1 accuracy regarding gain is around 0.2dB. If you are happy with that error range, keep λ/4 radbox.
Otherwise, use λ/2 radbox, and if simulation time permits a third simulation with an even larger radbox, check accuracy again.

thx.it was usefull