[Antennas] End-fed half-wave religion

[George, W5YR]

Jim,

In about 1948 I operated a 260 ft "longwire" antenna mostly on 75 and 20.
The "far end" went across an open field - I was a kid still living at home
in the country! - to a signpost at my Dad's store, about 20 feet high. This
near end went to a 20 ft homemade wooden tower that supported my ten-meter
beam.

I fed this wire with a parallel tuned circuit mounted on the shack wall by
the window through which came the end of the wire which was connected to
one end of the coil. The other end was floating . . .

A center link on the coil was connected by TV twinlead to the swinging link
on the 813 final tank circuit. I resonated the circuit by either of two
means:

1. during the night I would tune for max brightness of a 40-watt
fluorescent tube fastened along the wire at its far end. 

2. during the day, I would tune with a wooden pencil drawing arcs off the
open end of the coil.

In either case, the variable cap was tuned for max light or max sparks.
Then the final was re-dipped and reloaded as needed.

Before the hee-haws begin, that was a tremendously successful antenna!
Although quite low to the ground, I could work just about anything I could
hear on the old HRO-5TA1 with about 175 watts coming out of the 813 final
amp.

My point in all this memory-dredging is that I operated that wire strictly
voltage-driven with absolutely nothing connected to the "other" end of the
tuned circuit. Sure, it was only a few inches away from the driven end of
the antenna so there was plenty of capacitance for the displacement current
to work with, etc. But it worked and all the power coming from that 813
went somewhere because the coil didn't overheat nor did the plate turn red. 

Exactly what happens with the open-wire feeder connected to the end of a
wire is not a simple subject. There are a lot of "it depends." But both
theory and practice confirm that such operation is not only possible but
reasonably efficient. If I remember correctly, W4RNL, LB Cebik has a piece
on his webpage that discusses this antenna and feed system. Probably do us
all good to find and read through it again.

Thanks to all the participants for his interesting discussion . . .

-- 
73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437


Jim Glover wrote:

> I doubt these antennas would work if real-world components strictly
> obeyed the properties we ascribe to the models we use to predict their
> behavior.  If transmission lines could *only* transfer power, and
> nothing else, we'd be out of luck, after all.

<much snip>