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:
Placement of elements along boom (EMC)
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August 20th 03, 05:52 PM
Richard Clark
Posts: n/a
On 20 Aug 2003 05:27:15 -0700,
(Abdullah Eyles)
wrote:
The antenna has been assembled, but the elements were not placed as in
the photo (see pdf). Let me try to explain:
The short answer: start over and do it right.
The elements were not placed diagonally opposite, as I imagine is
required. (If the uppermost longest element is on the right, the next
lower longest element should be on the left, as far as I can
understand.)
Description is vague at best. You are starting off with a presumption
that may be faulty as you infer.
I imagine that this will affect the directional 'balance' of the
antenna, although I have no prior knowledge of EMC testing, just a
basic understanding of antenna theory.
Guessing aside, and taking a clue from this "diagonally" expression, I
would offer that you look at the antenna from above as you attempted
in your picture and see if it looks like:
+
|
| +
| |
| | +
| | |
| | | +
| | | |
.---+-----+-----+-----+----. two rails, one hidden by top
| | | |
| | | +
| | |
| | +
| |
| +
|
+
And confirm that each element, in order on one side, alternates
between the two rails that hold them. This is equivalent to:
+ element 4-B
|
| + element 3-A
| |
| | + element 2-B
| | |
| | | + element 1-A
| | | |
.---O-----+-----O-----+----. rail A
.---O-----+-----O-----+----. rail B
| | | |
| | | + element 1-B
| | |
| | + element 2-A
| |
| + element 3-B
|
+ element 4-A
Where the connections of elements denoted by "O" pass to the OTHER
rail. Both sides (common elements of any dipole pair) swap at each
step down the progression.
73's
Richard Clark, KB7QHC
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