# 从nanowire hyperbolic metamaterial 里面获得s parameter

s.fsp (591.6 KB)

1. 谢谢！ 应该可以考虑成2D仿真！
2. 我原来发表的是这个 How to extract s-parameter of my nanowire hyperbolic metamaterials ， 但没有人回复，我就发在中文版了。

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I want to understand the meaning of the source code of S parameter analysis group shown below.

Analysis/Script/Low 209-211 & 212-214

n1 = (-1ilog( x+1isqrt(1-x^2) ) ) / (kd);
n2 = (-1i
log( x-1isqrt(1-x^2) ) ) / (kd);
n = (imag(n1) >= 0)*n1 + (imag(n1) < 0)*n2;

z1 = sqrt( ( (1+S11)^2-S21^2 ) / ( (1-S11)^2-S21^2 ) );
z2 = -sqrt( ( (1+S11)^2-S21^2 ) / ( (1-S11)^2-S21^2 ) );
z = (imag(z1) <= 0)*z1 + (imag(z1) > 0)*z2;

Why do we have to separately consider n1 and n2, or z1 and z2, with different symbol of “sqrt” in each equation? What is the meaning of the equations of n and z?

This is originated from the two branches of the square-root of a complex number. Mathematically both branches are correct however only one branch satisfies the physics, eg., passive device cannot have gain.
n is the extracted effective refractive index;
z is the extracted impedance.

The above script works well for Smith’ example, it may not work well for other devices.

Thank you very much.

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You are welcome!