[HCDX] bentonite

["Sam Dellit" <dellits@xxxxxxxxxxxxxxx>]

there has been reference to bentonite (kitty litter) as an excellent means
of increasing the effectiveness of ground stakes.  in kraus and carver
"electromagnetics" there is a reference in a brief discussion about "space
cloth" - the stuff they coat the stealth bombers with to absorb rather than
reflect radarsignals.  it is stated that "a lossy mixture of a high-u
(ferrite) material and a high-e (barium titanate) material can be used
effectively for wave absorption if the ratio u/e is equal to that for free
space (ur/er = 1).  the mixture constitutes a physical disconinuity but the
wave enters it without reflection.  the velocity of the wave is reduced and
large attenuation can occur in a short distance."

is bentonite the same as barium titanate?

i have often wondered whether you could hang a bag of this stuff from a tree
and run the end of the beverage antenna through it. this would provide a
broadband termination to a beverage, completely eliminating any reflected
wave from the end doesn't necessarily lead to maximum front to back. do you
think we could get a few bags of ferrite cheaply
from somewhere to experiment (maybe that out of spec 43 mix that was
floating around sometime ago).

all this relates to my k9ay reduced Q loop/vertical antenna research. by the
way the naswa article actually starts to get close to a reasonable
explanation. also i would appreciate it if someone with an operating k9ay
could completely short out the "terminating resistor"/Q dampener and
resonate the loop to the frequency of interest and compare signal strength
for a station in the k9ay maximum i.e. k9ay loop to single turn resonant
loop. the signal should theoretically increase by about 20dB due to
combination of nil dampening and significant Q, albeit trading cardioid
pattern for figure 8. if this works it could be easily implemented with some
further options in the controlling switch box.

and finally to the point of all this. (i think i hear the sighs of relief).
many of us will recall the excellent work many years ago of gordon nelson
from the nrc on extremely high
Q perfectly balanced box loops - did he initiate the altazimuth loop design?
my recollection is that 80dB+ nulls were being obtained at a time when
ordinary loops were achieving about 40dB.
the altitude variation (that is tilting the plane of the loop) was both to
allow for skywave arrival angle and or
the cross-field/travelling wave component due to finite ground conductivity.
since the k9ay loop is fixed in the vertical plane and wave tilt is quite
large over poor earth, this may be a factor limiting achievable null depth.
may also explain why some dxers report the need to make extra efforts with
earthing.

just another shot of my two cents worth

73s gd dx de

sam dellit vk4zss

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