U.S. Islands Awards Program
The following ramble is from someone who
doesn’t care about SWR or resonance when it comes down to
wave, multi band large loops. I just like to get as much wire
as high as possible and work all bands I can with an ATU. My
books show the results!
Full wave loops are popular on the Amateur bands because they work
well, are multi-banded, inexpensive to make and somewhat easy to
install. Loop antennas have always fascinated me.
put, loops work well even at modest heights. Shortened loops
work well for those who don’t have the space for full wave
loops. I use a ¾ wavelength 20m rectangular
“indoors” from my apartment and am quite pleased
performance on 15, 17 and 20 meters (10 and 12m were always dead when I
Common loop shapes are; round, square, rectangular or triangular (aka
delta loops). The larger the area of the loop, the better
you will have. The number of antenna supports required depends on the
shape of your antenna. Round is impractical for most hams
it requires many supports, and obviously a square loop or rectangular
horizontal loop requires 4 or 2 for vertical polarizations.
Ladder line is probably the best way to get the signal in to your shack
according to many sources, but I’ve always used coax (RG-8 or
RG-8X) and sometimes without a balun (some hams recommend using a high
performance/high power 1:1 or 4:1 CT balun when using coax).
however recommend an air choke balun on all loops (1) to eliminate
stray RF and hopefully keep your neighbors off your back!
wave, closed loop antennas are broadband, low Q devices and exhibit a
theoretical gain of approximately 2 dB over a half wave
It’s hard to believe says VE2BMC, but going from a
wavelength vertical to a simple rectangular loop can lead to 3-4
“S” units improvement. That should be an
The standard full-wave loop formula is 1005 divided by frequency
(MHz). So, if we want to determine the length of a full wave
on say 40 meter phone, we’d use 1005 divided by 7.180=140
(see chart below). Perhaps the hardest decision
to make is do I make it a horizontal or a vertical loop? The radiating
element or wire position in relation to the ground determines polarity
whether it is vertical, horizontal or a combination of both.
the wire is parallel to the ground, it radiates horizontally. If the
wire is perpendicular to the ground, it radiates a vertical wave. If
the wire is slanted, it radiates waves, which have both horizontal and
vertical qualities. Since I’ve used both over the
and I also like the performance of vertical antennas, the vertical loop
has the best of both worlds for me plus it is easier to
In conclusion, if I could only put up one antenna, it would be a 160
meter full wave vertical loop- preferable two to cover all directions!
HORIZONTAL MULTI BAND LOOPS
height is 40 feet or more (higher is better!) but lower heights work
well too. No matter where a horizontal loop is fed, having
corners or no corners, it will always yield horizontal
Feed horizontal loops at any convenient spot. To date my
horizontal loop was an 80m full wavelength beauty (2)!
VERTICAL MULTI BAND LOOPS
recommended as above. If you have poor soil conditions, it’s
not to use vertically polarized loops. That’s an
factor to keep in mind, but if you have the height factor (3) it may
not. A vertical loop may be horizontally or vertically polarized
depending on where you feed it. Feeding at a corner or
produces vertical polarization. Vertical loops are good DX
antennas. Configure as a circle, square, rectangle or
(delta). The larger the area of the loop the better it will
work. Feed square and rectangular vertical loops at a corner,
triangular loops place apex up and feed at one low side
Many antenna elmers note that the DX performance is better on a delta
with vertical polarization. To date my favorite portable
loops are ½ wavelength on 80m (4 and 5).
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