STL creation for customAntennaStl?

I'm trying to do some antenna analysis requiring models outside the geometries included in the antenna toolbox. I've tried uploading several STL models, placing feeds, and attempting some analysis (specifically 'pattern'). When trying to create a directivity diagram via pattern, matlab hangs as busy until forcefully closed.

I suspect that MATLAB is hanging because the geometries I'm using are closed (3D watertight meshes), while most of the MATLAB provided antennas are a thin mesh with no interior. See code below. I can't attach STLs, so I've provided a link to the STLs I tried analyzing here: https://www.thingiverse.com/thing:4699096

I'm using models of v-dipoles as they should be simple geometries with verifyable results. They have not worked.

What are good external tools for creating thin meshes that are usable for antenna analysis? Or is there something else going on?

clear 
close all
f = 137.4*10^6; % frequency

c = customAntennaStl('FileName', 'Vdipole_simple.STL');
c.Tilt = 90;
figure
%c.createFeed(); % I've tried using this as well as create feed below
c.createFeed('FeedLocation', [546.6, -0.3475, 10], 'NumEdges', 1)
show(c)

figure(1)
p = PatternPlotOptions;
p.SizeRatio = 1.2;
p.Transparency = 0.7;
pattern(c, f, 'patternOptions',p); % it hangs here