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I am looking to simulate the radiation pattern of a 2.7Ghz half-wavelength dipole antenna immersed in salt water.

I've been using Altair FEKO software to try and accomplish this. I've tried two different ideas without much success:

Idea 1) Directly change the properties (relative permitivity, conductivity, density) of the free space medium.

When I start changing these properties far from their defaults I start getting a lot of geometry errors. For example, to model salt water, I give the free space medium a relative permitivity of 80 and a conductivity of 4 S/m. But then trying to solve this model gives "ERROR 114: Segmentation rules have been violated (wire segment is too long)". I attempt to resolve this by shortening the length of the dipole antenna to wavelength/10, but then I start getting mesh errors like "WARNING 18189: The geometry is much smaller than the model extents. This could cause tolerance issues." Is this normal? Do I need to just keep playing with the antenna vs mesh dimensions until it works?

Idea 2) Create a sphere surrounding the antenna and assign the region a new medium with the correct properties.

I create a sphere with a width several times the length of the antenna, but no matter what medium I assign to the region inside, FEKO treats it as a lossy space. For example, giving the region the default free space medium, and the faces are all perfect electric conductor, results in all gain from the antenna being destroyed and "WARNING 3397: The power loss is larger than the active power". Shouldn't a spherical region of free space be treated the same as the rest of the free space geometry? Why does FEKO treat it differently?

I know this is possible because I've read several research papers talking about using FEKO to model antenna underwater, but so far I haven't figured out the key.

Any suggestions?

I'm also open to switching to Matlab if someone believes it would be easier to use that.

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