On Feb 14, 3:21 pm, ml wrote:
I.....verse with it; it would work to fill a

volume around the antenna. But to get the full effect, it should be a
pretty large volume, containing the electric field in the neighborhood
of the antenna. Not very practical. In coax, the electric field is
between the wires; in the dipole, it's also between the wires, but the
volume is very much larger. On the other hand, people have been
shortening resonant antennas for a long time by increasing the
inductance: thus, loading coils and "slinky" antennas.

Similarly,

people make "slow" coax by making the center conductor a helix, and
thus make delay lines.

Cheers,
Tom

ok what is a 'delay line'??

i would think that would just increase the surface area and therfore
sorta increase performance

Wikipedia gives a definition of delay line; a length of transmission
line is technically a delay line, but often for longer delays, a
special line is made in which the center conductor is a wire wound
around a core (often of the same material as the dielectric between
center and outer). The winding should be done with space between the
turns, not close-wound, to give more uniform delay versus frequency.
For a uniform TEM transmission line, the delay time is the square root
of the total capacitance between the conductors times the total net
inductance of the length of the conductors: Tau=sqrt(L*C). Many E&M
texts go into how to accurately calculate the inductance and
capacitance for coaxial line with straight conductors.

In an antenna, you can increase the inductance by adding a lumped
inductance, commonly called a loading coil, or you can replace the
straight wire with a wire formed into a helix. Google "slinky
antenna". You'll find lots of info. I'm not making any claims that a
slinky antenna is either a good antenna or a poor one; it's just one
way to make a shortened dipole or monopole antenna, or even a
shortened Yagi.

Cheers,
Tom