DELTA LOOP ARRAYS
antennas document shows the 80 meter band 5 elements delta loop
array in use at VA2GU starting Jan 2011.
The array consists of five full size loops (300
feet of wire for each loop) erected between two 80 ft towers,
spaced 300 feet; the loops are suspended on a quarter inch polyester
double braid rope, running over two marine types pulleys.
Due to consistently very high winds along with
up to 1 inch radial ice, a special arrangement had to be designed
to support the loops' apex, allowing torsion, sway and every
motion that high wires are subjected to.
what seems to be reliably working.
The ice problem was addressed by designing
a feed system what allows running 15 amperes through each loop
without affecting the phasing components; this generates the
heat to prevent ice buildup.
The loop design in use is horizontaly polarized (feeding
at center of the base wire). The main reason is that the array is shooting
straight into that 85' vertical steel structure, with a similar interference
in the back. Modeling showed significant coupling into both towers. It
was easier to change the polarization to horizontal, rather than detune
the towers. Besides, using TA (terrain analysis program by K6STI) and NFTA
by N6BV showed that with the 18 degree slope from 1000 feet elevation to
salt water 2600 feet away in beam direction, did not affect my gain/elevation
Another consideration was to minimize wind drag;
14ga copperweld wire of 40% conductivity was selected. Many of
you will say: "too much resistance...."
You can be excused for your ignorance (i did
not say stupidity! ignorance is merely not having been exposed
to the facts, or refusing to recognize them). You can refer to the
excellent pdf document by N6LF:
and educate yourself on the use of copperweld wire for antennas.
You can click on that file, if you want to read it.
5loops.jpg is the configuration
of the loops, drawn over with colors; this was necessary because
this array is particularly stealth in nature except for the support
the parameters and characteristics of the array, as is presently
being used for 80 meters.
You will notice the large impedance variation
between winter/snow and summer/dry rock resistivity.
This winter, i will be recalculating my values
and provide a second phasing scheme.
VA2GU has developped
an approach to fully design and implement the phasing of any array
of antennas up to 5 elements.
The methodology involves the use of complex
numbers in programs developped by VA2GU to arrive at the complex
impedances of the various elements in the array. In the ten steps
involved, the network components required for the proper phasing and
impedance transformation to the transmitter are calculated. AND NO, I'M NOT TRYING TO SELL YOU ANYTHING;
THIS IS FREE!
Refer to ANTENNAPHASING.HTM
for complete details.
Site design by