Z is close to +58-j138 ohms.

A small inductor of 0.88 uH in series with the antenna should provide a
pretty good match to 50 ohm coax.

Larry D wrote:

I want to construct a 5/8 wave ground plane for 24 MHz.
I am OK with the dimensions, but I can't get a grip on what
the impedance at the feedpoint will be. Even the ARRL
antenna book hasn't been much help.

Can anyone tell me the impedance I can expect to see,
also any tips on matching it? Thanks!

Larry DiGioia N8KU
N8KU at longwire.com