Understanding Coplanar Stripline Antenna

[rxb]

Hello all. I don't have much training in transmission lines so my question is pretty general.

I've been tasked with creating a coplanar antenna on top of a small silicon cantilever which will just be held in air, thus the need for a single plane design. The goal is to produce a large magnetic field at the tip of the cantilever and I was given a reference from which to work. I know we cannot post images or provide links to published works here, but the paper is called "Coplanar stripline antenna design for optically detected magnetic resonance on semiconductor quantum dots," so if you have access or are able to find this paper please take a look. If you can't essentially they have a coplanar waveguide (CPW) which transitions to a coplanar stripline (CPS). At the end of the line the two traces of the CPS are shorted together.

So if I understand this correctly, a shorted transmission line like they have there will result in a reflection coefficient of -1. Meaning the wave will travel back along the line with opposite polarity causing the voltage to subtract but the current to add since it is negative traveling in the opposite direction? If that is the case and I am designing a shorted line using a software like Sonnet should my goal then be to get S11 close to 0 dB?

 

[BigBoss]

If you adjust well the length of the Tranmission Line, you can obtain a short circuit effect with S11=0.
But this will be valid at one single frequency only.If your goal is to work at one single frequency, it's OK.
Sonnet can certainly be used to simulate the Transmission Line.
Here, the problem can be arised from Dielectric Coefficient.This coefficient is frequently dependable on temperature and the frequency.If you are able to align this coefficient, you may obtain very close results in measurements compare to simulations.