Purdon my deep egnorance, but, why do we tend to use thin conductors
for antennas? I know of only few counter-examples, all at VHF and
above:
- a discone can be made of sheet metal, rather than thin radials
- a log-periodic broadband dipole can be made as an etched spiral
pattern on PCB (and I guess it can't be made with constant section
conductors at all...)

I know that things get more complicated at higher frequencies, what
with slot antennas & suchlike.


A connected curiosity is regarding short active receiving antennas on
HF. My concern is putting together an efficient, mobile mounted,
all-band HF receiving antenna. If we use short whips, they show an
extremely high impedance and require a carefully designed matching
amplifier. At such high impedance levels, a broad 3-30MHz bandpass
filter may not be easy to design - so I have been told.

But I wonder - why not use 1-2 sqft of conductive surface instead, e.g
PCB or big bore copper rainpipe, worked against the car body?

I just ran an unscientific experiment. I grounded a pocket HF
receiver to a steel-topped table, and balanced a steel pot lid on the
top of its collapsed whip antenna. Signals were booming. A 10" PCB
disk, placed 5" above the steel roof of a car shouldn't be much
different.

Comments?