Topband: "Magnetic Receiving Loop / small loop , brief summary.

[Tom Rauch]

> Many successful low-band operators seem to have forgotten
their roots. Who ever started out with 1500 W, phased
verticals, and several Beverage antennas? Arcane knowledge
and the appearance of exclusivity feed the ego, but don't do
much to increase activity. IMO the ON4UN book has progressed
from a pretty useful handbook to a photo album of big-gun
stations, with small-scale antenna possibilities tossed in
as an a sidebar. We need a beginner's guide to 160. As I get
active on 160 and develop some experience I will post
information on my Website ( http://kr1s.kearman.com/ ), but
we could use it now. For starters, how about a portable loop
antenna that is built according to good engineering
practice?

Jim,

The problem is small magnetic loops are not what people
think they are. I expanded my web page on small loops a bit
and reworded some things.

http://www.w8ji.com/magnetic_receiving_loops.htm

Any receiving antenna, outside of very close noise problems
within perhaps 50 meters of the antenna, all comes down to
polarization and directivity. The small loop has a very
sharp null line through the axis, but a very wide low
directivity response in all other directions. The
polarization changes with direction also (as it does with
many antennas).

Something like a K9AY, Flag, or EWE would be the next step
up.

Two phased elements would be another step up from that.

A Beverage or REAL four square (two crossed K9AY's are not a
four square) elements would be next.

Finally an eight circle array or phased Beverages would be
the ultimate.

The problem I see with repeating small loop articles, snake
antennas, and other Edisonian design method antennas is they
mostly improve things through a bit of circumstantial good
fortune mixed in with the cut and try. Many antenna like
this don't actually work or behave anything like articles
claim, although I certainly agree it might be a good idea to
show a couple optimum element designs that people could try.
There certainly are situations that could be improved with a
small loop, especially where there is one single strong
noise source arriving from one direction. Unfortunately
there are even more situations where the is no benefit over
just using whatever is already there, say the transmitting
antenna.... or even a forty meter dipole or some other
antenna that might unexpectedly provide some improvement
through luck.

Someone could write an entire three inch thick book based
entirely on small antenna articles that are everywhere and
the ones that would actually work as described would
probably only fill five pages.

73 Tom