The recent thread on 8 circle arrays prompted me to create a few different
AutoEZ models, mostly because I was curious about the relationship between
array size, element phasing, and number of active elements (4 with W8JI, 8 with
Hi-Z).
First thing I did was educate myself. For "W8JI type" arrays:
http://w8ji.com/small_vertical_arrays.htm
http://n3ujj.com/manuals/8%20Circle%20Vertical%20Array%20for%20Low%20Band%20Receiving.pdf
http://www.dxengineering.com/parts/dxe-rca8b-sys-3p
http://static.dxengineering.com/global/images/instructions/dxe-rca8b-sys-3p-rev3.pdf
Low-Band DXing, 4th ed, ON4UN, Chapter 7, Sections 1-21 and 1-30
And for "Hi-Z type" arrays:
http://www.k7tjr.com/need.htm
http://www.kkn.net/dayton2014/HiZ_DAYTON_2014_7n2.pdf
http://www.hizantennas.com/HiZ8-160&80_users_guide.pdf
http://www.hizantennas.com/Hiz_8_160&80_manual.pdf
http://www.dxengineering.com/parts/hiz-8a-lv2-160-2
Then I created models where the array size (diameter) can be controlled via a
single variable, along with another variable to control the phasing. For
example, here's the AutoEZ Variables sheet tab for a W8JI type array. The Hi-Z
is similar except that array size is specified in feet (or meters) rather than
wavelengths.
http://ac6la.com/adhoc/8circle1.png
Since everything is controlled by variables you can run "variable sweeps"
changing one or more parameters. Here's the W8JI array with the spacing ("B")
held constant while the phase delay ("P") is swept from 80 to 140 degrees. For
each test case AutoEZ will automatically calculate the RDF (last column).
http://ac6la.com/adhoc/8circle2.png
When the calculations finish you can step through the 2D patterns. Here are
the elevation and azimuth (at 20° TOA) patterns for 0.604 wl broadside spacing
and 125 degree phasing, as shown by "B" and "P" in the lower right corner.
http://ac6la.com/adhoc/8circle3.png
You can run similar sweeps changing the array size while holding the phase
delay constant, or hold both size and phase constant and do a frequency sweep,
or use the "Generate Test Cases" button to create any combination. For
example, the setup below would vary broadside spacing "B" from 0.50 to 0.70
wavelengths; for each "B" the phase delay "P" would be varied from 115 to 135
degrees; all at a constant frequency of 1.85 MHz. That would be 25 test cases.
You can run thousands if you like.
http://ac6la.com/adhoc/8circle4.png
You can also show 3D patterns. Here's an example of a Hi-Z array, diameter 200
ft with ±106 degree phasing, along with the 2D elevation pattern.
http://ac6la.com/adhoc/8circle5.png
And here's how the RDF for a 200 ft Hi-Z array varies as the phase is swept
from ±100 to ±112 degrees.
http://ac6la.com/adhoc/8circle6.png
For both of the array types, I created one model using W8JI-style top hat
loaded vertical elements (per the sample model on Tom's site) and a second
model using simple aluminum tube elements (per the four-section, 23.25 ft, Hi-Z
AL-24). Here are the models. Save to your computer then use the AutoEZ "Open
Model File" button.
http://ac6la.com/adhoc/W8JI_8_Circle__TopHat.weq
http://ac6la.com/adhoc/W8JI_8_Circle__AL-24.weq
http://ac6la.com/adhoc/Hi-Z_8_Circle__TopHat.weq
http://ac6la.com/adhoc/Hi-Z_8_Circle__AL-24.weq
Please note that these models have not been reviewed or approved by the authors
of the references cited above. Any mistakes or misinterpretations are strictly
mine. And the models may or may not be an accurate representation of any given
commercial package.
In all the models, a single variable ("X") controls the segmentation. You can
reduce that to speed up the calculations. You can also run a sweep on "X" to
do a convergence test for model accuracy.
For comparison with the 8 circle arrays, here's the W8WWV "Benchmark Beverage"
model. With this one you can "sweep" the length and/or other parameters.
http://ac6la.com/adhoc/W8WWV_Beverage.weq
Greg's Beverage page for reference.
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/Beverage.htm
Calculated results for this Beverage are shown in section "Calculate 3D Data"
here.
http://ac6la.com/aeuse3d.html
===============
AutoEZ is an antenna modeling program which uses Microsoft Excel in combination
with EZNEC.
http://ac6la.com/autoez.html
Current AutoEZ users, see here for recent maintenance updates and instructions
on how to get the latest release.
http://ac6la.com/aechanges.html
Dan, AC6LA
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Topband Reflector Archives - http://www.contesting.com/_topband
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