Jerry Martes wrote:
"It seems that the 1/4 wave stubs that shunt the feed point might
strongly affect the input impedance."

Not at the resonant frequency.

Don`t sweat twin lead VF in an antenna as radiation is from common-mode
current.

The marvelous 19th edition of the ARRL Antenna Book has Fig 17 on page
24-14. It`s "Lumped-constant circuit equivalents of open and
short-circuited transmission lines". Note (A), the top figure, which is
a short-circuited stub of any length less than 1/4 wavelength. It is an
inductance! Also note (C). It is a short-circuited stub of exactly
1/4-wave:

Equal to a parallel resonant circuit, a "very high" impedance. So high
in fact that many in parallel would not be noticed.

Best regards, Richard Harrison, KB5WZI