[TowerTalk] FW: Help - 80m 4 square

[w8ji.tom]

> Performance wise it seems to beat the slopers, dipoles and other cloud
> warmers. It will not compete with the beams, but there are not that many
> beams on 80 meters anyway. 

I don't know how this relates to 80 meters, but I have extensive 160 meter
data taken during a series of tests morning after morning on 160 meters
with VK3ZL and ZL2REX, and other DX stations.
 
I have a pair of phased dipole at 250 feet on 160 meters. That certainly
must qualify as a beam of some sort, since it shows about 5 dB gain over a
single dipole at 250 feet.

My four square equals or beats the high phased dipoles 72% of the time when
I include the sunrise band peaks. When I toss those peak times out of the
data, the four square beats the dipoles about 97% of the time.

These numbers are based on over 400 reports from DX on 160 meters collected
over a six month period.

With a poor ground system, it is the other way around. Using four elevated
radials on a test vertical, a high dipole "whipped the stuffing" out of the
vertical time after time.  The VERY SAME dipole never beat a vertical with
60 1/4 wl radials, unless it was a QSO within a few hundred miles.

A field strength meter confirmed a six dB change in FS by adding 60 radials
slightly buried, when compared to the same antenna with four elevated
radials. I never measured one radial, but with two radials FS approached 10
dB down. This was with an antenna in a absolutely clear open pasture. 
 
'>Oh!...I forgot to mention the sloping part.
> ON4UN states that if you come more that 19-20 degrees off vertical you
> loose the vertical component.

The vertical radiation, when sloping a wire some angle off true vertical,
is always attenuated less than the cosign of the angle. For example, at 45
degrees of slope field
attenuation is: cos45 log20 or .707 (the cosign of the angle 45 degrees)
times log20 (the formula for voltage change expressed as dB). Radiation is
3 dB down or less with a wire slope of 45 degrees.

20 degrees off vertical, radiation would be cos of 20 times log 20, or .54
dB down in the worse case possible.

The antenna does not loose significant vertical component until the angle
approaches 45 degrees.

This is the same thing that makes an inverted V remain mostly horizontally
polarized with apex angles of more than 90 degrees.

>I use only one radial. There is not that much advantage to adding
> more radials.

Except about a ten or twenty-fold increase in efficiency! I can't imagine a
single radial working efficiently, even over salt water. 

73 Tom

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