On 11 Nov, 05:19, "Richard Fry" wrote:
"art" wrote

It has been stated on this antenna newsgroup that with
short antennas the current goes up the radiator and then turns back
and goes down. If this is so then it must be radiating all the time,
yes? If a radiator is radiating all the time then the efficiency is the
same as a full leght antenna. Yes? This does not conform with
reality Right?

Wrong, as regards your "reality." Using the classic definition of
efficiency, an antenna of ANY length (including a point source) will radiate
nearly 100% of the power it accepts from the r-f source driving it.

The radiation patterns of those antennas will vary. Some will radiate more
relative field in some directions and less in some directions than others
will. But, disregarding dielectric and conductor I^2R losses, ALL antennas
radiate ALL of the power they accept from their driving source (ie, their
efficiencies are equal).

So is it possible that the circuit (current) returns along
the path down the center of the radiator...

No, it's not possible. No matter the direction of flow along a solid
conductor, alternating current tends to travel on/near its outer surface.
This is due to the greater number of enclosed lines of magnetic flux
generated by current flowing at/near its center, which increases the
inductive reactance of the conductor in those areas. The result is a
redistribution of the current to the parts of the conductor cross-section
having the least reactance, ie, on and near its outer surface. Read
Terman's RADIO ENGINEERS' HANDBOOK, 1943 edition, pp 30-31 for more on this
(or many other sources).

IF it was possible then radiation figures accepted by hams
would coincide with respect to short antennas. Yes?.
Then why do all the "experts" reject the notion of the circuit
continueing down the center of the radiator?

Because it doesn't do that.

RF

To say that an AC current will not flow in copper unless it has clear
axis
access to the copper surface is balderdash. Cover the copper with an
insulator
with any thickness that you desire for safety incase you are in error
and then drill
into the center of the copper. Without a safe guard you will die!
What provides resistance on the outside als skin depth can by the
reverse contain current flow to the inside. You like many use the word
"tends"
with respect to external current flow. The word "tends" does not
make the current passage an undeniable fact. Yet you have hung
your hat on that premise. I repeat...balderdash
Art