S parameter extraction fails



Hey all,
I am trying to extract S parameters from a triangular split ring resonator but the analysis keeps saying that there is too much spatial variation in the fields. I have placed the monitors very (VERY) far away (more than 2*lambda) and yet I am still getting this error. Any ideas?


S-Parameters calculation - error message - too much spatial variation of the fields

Hi Max,

This error can occur if the structure diffracts light to higher grating orders. The s-parameter analysis assumes that only 1 grating order exists in which case as you get far enough away from the structure the light will behave as a plane wave with uniform field intensity across the simulation region span. Metamaterials typically have a period which is much smaller than the wavelength of light so this assumption is typically good.

However if additional grating orders are supported, the fields will not have a uniform intensity. In this case, it is possible to modify the analysis script to calculate the S-parameters for only the zeroth grating order as discussed in this post:

The above post also discusses how to determine whether the structure supports higher grating orders.


TSRR agreement simulation_s parameter extraction_to be uploaded.fsp (280.0 KB)

I’ll take a look at the diffracted orders and see if anything interesting pops up. Thanks for the help!