On Wednesday, November 5, 2014 2:16:04 PM UTC-6,
There is little practical reason for shortning 23 cm band antenna,
but antennas for 160M are a challenge for most people that live
in an urban area.

Where I live anything over about 30 feet tall is basically a no-go.

So in the interest of practicallity and maybe getting something usefull
out of it, how about a 160M antenna with a maximum height of 30 feet
as a goal?

That immediately eliminates dipoles as a 160M dipole at 30 feet will
radiate most of the power straight up.

In that case, I'd use a "T" vertical, with the loading coil at the base
if the top wires are too short to tune the antenna. The main reason
for having the coil at the base is ease of changing the inductance,
and the top hat wires improve current distribution vs a whip with
no top wires. If no room for the top wires, I'd use a capacity hat if
possible.