Radio waves get through wire insulation, even if it is very thick, just as
if it isn't there.

It is necessary only to remove the insulation at the end of the wire where
it has to make electrical contact with the radio circuits.

Reminds me of my first crystal radio!

I stripped the insulation from about 100' of phone wire, and western-unioned
all the splices (kids don't often have 100' of wire in less than 20
pieces).. Later, I learned that didn't actually help..
However, it did make the wire lighter, which wasn't a bad thing.. Soft
copper does have it's limits..

I remember the thrill of picking up CHICAGO!

The project came to an untimely end, due to the antenna being up as high as
I could reach, which coincidentally was neck-high for the mailman.. Copper
wire isn't that easy to see..