3 Element Beam Comparisons

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3 Element Beam Comparisons
Hey! Aren’t all antennas the same-o same-o perfectly
designed.
By
Wb6dco
Joe Perry jr
What to show about nothing!
• The problem to solve is how to make a perfect 3
element beam.
• These are 3 element MONO Band beams.
• Make them perfect in every way.
• Then we will combine them all into one not so
perfect beam of many elements.
The picture of a perfect Beam
Beam Elements Calculated by
WA7RAI Software
• His software has auto mode, auto gain, or
optimized gain or maximum forward gain.
• We will use the auto-auto-optimized
analysis for these beams.
• Following are the element dimensions and
spacing charts.
14.1 MHz 3 Element Mono Beam
14.1 MHz translated to Inches
•
•
•
•
•
Reflector Half Length
209.4”
Reflector Spacing to Driven 167.53”
Driven Half Length
204.36”
Driven Spacing to Director 125.64”
Director Half Length
193.14”
14.1 MHz Beam launch angle 33 deg’s
28.2 MHz 3 Element Mono Beam
28.2 MHz Dimension in Inches
•
•
•
•
•
Reflector Half Length
104.7”
Reflector Spacing to Driven 83.76”
Driven Half Length
102.18”
Driven Spacing to Director
62.82”
Director Half Length
96.54”
28.2 MHz Beam Launch 19 deg’s
50.1 MHz 3 Element Mono Beam
50.1 MHz Dimensions in Inches
•
•
•
•
•
Reflector Half Length
Reflector Spacing to Driven
Driven Half Length
Driven Spacing to Director
Director Half Length
58.93”
47.04”
57.48”
35.28”
54.3”
50.1 MHz Beam Launch 11 deg’s
3 Element Mono Bands
• Here are the EZNEC demo outputs for
some beams
• 14.1 mhz 11 gain
26 B/F
• 28.2 mhz 13 gain
21 B/F
• 50.1 mhz 11 gain
9 B/F
• These represent standard 3 element beam
design
Change the Reflector Length to 209” per side to see this
effects the 28.2 MHz beam.
Appears that the 28.2 beam with the
longer Reflector does not change that
much. 12 dBi down to 11 dBi.
28.2 MHz with 104.7” (left picture) and then 209” (right picture)
Reflector half sides
Using the 14.1 MHz beam reflector of 209” half
wavelength, only changes the 28.2 MHz beam slightly.
So, we can move the 28.2 elements onto the 14.1 MHz
beam boom and see if both still work.
Merge 14.1 MHz and 28.2 MHz Elements on one beam boom. Drive
the 28.2 MHz Driven Element and see if it still works.
The 28.2 MHz beam still
works great with the added
other elements.
Now test if the 14.1 MHz beam will still propagate with the smaller 28.2
MHz beam elements sitting on the same boom.
The left plot looking down on the original 14.1
MHz beam with only 3 elements, and the right
plot is looking down with merged 20m and 10m
beam elements. Note the main Gain goes
down but is still usable good.
The launch angle changes from 36 deg’s down to 33 deg’s. The
merged 20m Elements and the 10m Elements seem to work together
and not destroy the propagation.
This is great, we can build a 3 element 20m beam and a 10m beam
and stick them on the same boom pole. We use the 20m Reflector
element for both 20m and 10m beams. The beam is tested at 300” (25
feet) above the ground.
The 10m
Beam
The 20m
beam
Total length of the boom is
about 300” or 25’.
Try putting the 10m beam out front of the 20m beam elements using
the Director as the 10m Reflector. What will that do, besides make the
boom longer.
10m inside
10m out front
10m elements out front of the 20m elements. Test what the 20m excited
beam does not.
This looks pretty
good. The SWR’s
are good also.
Can we merger MORE on the Boom. Like put the 50.1 MHz elements on
the boom using one of the other elements as the reflector?
If we look at the lengths of the elements on the
new beam, they go from 209” down to 96”.
So, the reflector element of the 50.1 MHz beam is
58.93” on one ½ side.
So 2 * 58.93 = 117.86”
Which of our elements are at least 118” long?
The Director of the 14.1 MHz beam is 193”..
So, we will try and use the 193” as a reflector for
6meter band.
Now merge on to the beam the 6 meter band 50.1 Mhz elements. We
excite the 14.1 MHz elements first.
Now look at the excited 28.2 MHz elements.
Oky for a final we test the 50.1 MHz elements in excitement. This has
some exciting parts. Lobes at 36 and 11 degrees forward and
backwards. So this may get around the sky pretty well.
Conclusions
• I don’t have any hi hi..
• It appears I can modify my 5 Wire beam
now to hold more wires on the front end
for 10m and 6m.
• This will still point directly East but the lobs
from the 3 sets of wires do not seem to
ruin each other in SWR or pattern.
• IT MIGHT WORK. Joe wb6dco
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