TopBand: 5/8 ~ vs. 1/2 ~ spacing

[Earl W Cunningham]

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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