Yuri Blanarovich wrote:
Thus, the shield IS the antenna, and the loop is the means to couple the
energy out of the short dipole. Thus, it really isn't a magnetic antenna at
all - it's a dipole!

Tom, W8JI has a better, more detailed explanation at his website (a great
resource) at http://www.w8ji.com/magnetic_receiving_loops.htm




Looks like another "debunked" fact by "Tom noname" W8JI.
(Welcome back Tom ?:-)

The shield IS an electrostatic SHIELD and wires inside are the ANTENNA.
If you want good efficient, electrostatically shielded small loop, take copper
or aluminum tubing, bend it in a circle about 1m diameter (for around 160m
band). I made it of two pieces, joined at the bottom in metal electrical box.
Top of the loop is open and insulated with plastic tubing. Then thread wire
through the loop, three turns, bring the ends into the junction box and connect
trimmer capacitor (about 1.5k ?) across the ends (not connected to anything
else). Then thread another single turn loop through the tubing. In the junction
box, connect one end to the coax shield and the second end to trimmer capacitor
(about 500 pF ?) in series with the center conductor of the coax. Shield and
mast holding it can be grounded at the installation place. I actually used low
power transmiter and SWR bridge to tune the loop, now there are nice antenna
analyuzers to do it.
The three turns are resonated to operating frequency with capacitor and that is
the ANTENNA. The single turn loop is the coupling and trimmer provides match to
the coax feedline. The tubing is a SHIELD which helps with suppressing the
noise and interference from nearby sources.
I have also used this loop as a coupling to Beverage antenna (positioned at the
end of Beverage), where it provided less noise than beverage alone.

Don't believe everything you read at W8JI web pages.

I would like to see a short "dipole" (NOT), really short piece of tubing, which
is attached to a mast and grounded to act as an antenna on low frequencies.
Having small loop, insulated and properly fed or coupled to, is another thing.
You can have single loop or turn antenna too, but above described antenna is
"magnetic" or electrostatically shielded small loop antenna which provides more
signal and better discrimination from nearby interference.

Yuri, K3BU.us

Don't believe everything you read here, either. For a good treatise on
how the shielded loop works, and what it's good for, read Glenn S.
Smith's (Georgia Institute of Technology) article "Shielded Loop
Antenna" in Richard C. Johnson's _Antenna Engineering Handbook_.
73,
Tom Donaly, KA6RUH