Roy Lewallen wrote:

Just a few weeks ago, I designed what amounted to a two-radial ground
plane antenna as part of a consulting job. It was made from copper tape
on a Duroid dielectric material, a lot like the window antenna John
described. An omnidirectional pattern was a requirement, and I was
concerned that either the flatness of the tape or the presence of the
dielectric might have some impact on the circularity of the pattern. So
I had it tested at a local lab. It was the most circular pattern they'd
ever seen, having about 1 dB maximum difference between any two directions.

Did this antenna include any provision to prevent current on the
outside of the feed line?

Which direction did the feed line exit the antenna?