Positive S11 parameters when modelling Loop antenna

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I am trying to model a circular loop antenna as part of learning COMSOL. For some reason no matter what parameters i change, i end up getting positive S11 parameter values.

I have tried the impedance boundary, scattering boundary, lumped port, and surface current density condition.

Am i missing any boundary condition, or other parameters?


1 Reply Last Post 2025/05/28 4:54 JST
Robert Koslover Certified Consultant

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Posted: 3 days ago 2025/05/28 4:54 JST
Updated: 3 days ago 2025/05/28 4:56 JST

S11 is a complex number. If you are plotting it, you are by default plotting the real part of it. Considered all by itself (in the absence of any other information) a positive value of the real part of S11 does not indicate that anything is necessarily wrong. That said, if you are new to using Comsol Multiphysics, you very probably have a variety of mistakes in your model anyway. You might want to consider posting your model to the forum.

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Scientific Applications & Research Associates (SARA) Inc.
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S11 is a complex number. If you are plotting it, you are by default plotting the real part of it. Considered all by itself (in the absence of any other information) a positive value of the real part of S11 does not indicate that anything is necessarily wrong. That said, if you are new to using Comsol Multiphysics, you very probably have a variety of mistakes in your model anyway. You might want to consider posting your model to the forum.

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