On Thu, 9 Oct 1997 09:06:59 -0700 "Lane C. Zeitler" <km3g@cts.com>
writes:
>Gentlemen,
>Looks like the 5/8 wave spacing provides almost an entire dB greater
main
>lobe gain over the half wave spacing for two verticals fed with zero
degree
>phase shift. Side lobes start coming into the picture using .625 ~
spacing
>however. BUT, the main "figure eight" gain over a single vertical
element
>is almost 5 dB whereas compared to the .5 ~ spacing it is about 4.0 dB.
>
>This doesn't take up that much more real estate. Five dB using only two
>verticals AND a bi-directional pattern is pretty good. I wish this array
>was going to be used on my property instead of my friend's.
>
>I am trying to find the half-power beam width for .5 and .625 spaced
arrays.
>
>Comments welcome.
>
>Lane
>Kilo Mexico Three Germany
>San Diego
================================
I ran this through EZNEC v2.0 for zero-degree phasing, 1/4, 1/2 &
5/8-wave spacing (also for .6666667-wave spacing, which gives greatest
broadside gain). Here are the results:
GAIN OVER A 3-deg AZIMUTH
SPACING SINGLE VERT BEAMWIDTH
-------------- -----------------------
----------------------------
1/4 wave 1.09 dB -2.51 dB @ 90 deg
1/2 wave 3.83 dB +/- 32.8 deg
.625 wave 4.78 dB +/- 25.6 deg
.667 wave 4.86 dB +/- 23.9 deg
Those values are for 1.83 mHz ground-mounted 1/4-wave verticals over
"average" earth (conductivity = 5 mS/meter, dielectric constant = 13) at
the elevation angle of maximum radiation.
For free space, the following values were obtained:
GAIN OVER A 3 dB AZIMUTH
SPACING SINGLE VERT BEAMWIDTH
-------------- ---------------------- ----------------------
1/4 wave 1.07 dB +/- 86.2 deg
1/2 wave 3.75 dB +/- 29.9 deg
.625 wave 4.72 dB +/- 23.5 deg
.667 wave 4.80 dB +/- 22.0 deg
73, have fun with the verticals.
de Earl, K6SE
-
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