I want to supplement my transmitting antennas with the most useful
low-noise low-band receiving antennas possible that I can put up in
dense forest and with extremely challenging topography.
My qth and surrounding woods are on a hilltop with extensive and steeply
angled jagged ledge, many ridgelines, ravines and wetlands and areas of
standing water and marsh, varying in height from ~ 750' - 820' ASL.
Past where I would be able to put receiving antennas, there are very
sharp dropoffs to South and West of several hundred feet. It is
beautiful but NIGHTMARISH to walk through the woods under the best of
cndx (like today) but it is a true HORROW SHOW when all the thorns
bushes and dense vegetation is growing rapidly and the Deer Ticks and
mosquitos are everywhere. It's even worse in snow as the ledge and rock
slopes become exponentially more dangerous to access and there is ledge
EVERYWHERE.
Complicating matters are areas of the woods that resemble the moguls on
a ski slope only more spread out. Some of these moguls can approach 30'
high with the ridgelines even taller than that. While they somewhat run
in the same direction ENE to WSW others run on steeply sloping hills
like a series of "steps". One ridge runs North to South on the side of
a hill; drops 15' feet then there is a another ridge then another drop
of 15' or so to a ravine and standing water and muck pond about 20'
across. And there are flatter areas of ledge that have what appears to
be a boulder on it about 5' high and 30' long right in the middle of a
flat spot. There are a few formations like this in other areas as well.
The result is that there are very few areas open for more than 100' in
any direction without running into these rock formations and steep hills
and dropoffs.
I have already studied the slide deck of Frank, W3LPL's excellent 2016
Dayton presentation, the beverage article co-authorized by W3LPL and
N0AX, any many, many articles from W8JI, ON4UN and many others. The
questions that I have are specific to my qth and, as far as I remember,
were not answered in what I have read.
Now that I have described the terrain, my questions will make more
sense:
1) What is the effect on a terminated directional beverage (terminated
at the back end that runs downhill at an 8% slope? If the lobe maximum
is at say 15 degrees on flat ground, does the lobe maximum drop to an
even lower angle? Or does the shape of the lobe change? or both?
2) Same question but with the beverage now running uphill at a 5% slope.
3) Same question but with a pair of phased beverages, one with a 20'
high "Hump" in the middle and the other without the "Hump". One
beverage starts and is terminated on a flat spot, runs to the top of a
ridge and then back down again on the other side. The other beverage
runs in parallel, somewhat downhill and not on a ridge.
4) If you put a phased array of verticals NW to SE (with pattern
broadside to the direction of the elements - receiving NE) in a flat
spot that then points directly into a high ridge to the Northeast 30'
higher than the flat spot and is only 50' from the front of the array,
have you essentially turned a low angle receiving array into a created a
high angle receiving array?
5) What happens when you have 4 ground mounted receive verticals with a
large 5' high boulder taking up all of the the space in the middle of
them? What does that do to the pattern?
6) Let's say that you have a 6 L array of receive verticals in 2 rows of
three with each line pointing NW to SE (pattern broadside NE) and they
are phased. But instead of being on flat ground they are on the side of
a steeply sloping hill so that the first row is at 820' asl and the 2nd
row runs in the same direction but at 800' asl and the rows are spaced
35' apart. How might that affect the pattern? (for purposes of this
question ignore the impact of ground being "ledge" rather than soil.
7) Now lets say that you have TRANSMITTING antennas for 160, 80 and 40
nearby. How far do the RECEIVE verticals and beverages have to
physically be from the radials of the 160 Inv L, 80 M 4-square and from
the elements of the 40 meter wire beam before the performance of either
the transmitting antennas or receiving antennas starts to degrade? Some
say they are fine without 30' of a tower or other antenna, others say
that any part of the receiving antenna must be at least a full
wavelength away from the closest radial or closest element of the
transmitting antenna. That's quite a difference in spacing! Which is
correct?
8) Does the spacing between beverages for different beverages matter as
long as the beverages cross each other? If instead the beverages run
parallel to each other, then what is the required minimum spacing
between them in wavelengths before their performance starts to degrade?
9) What is the impact on beverage receive performance if the RG6 Quad
Shield coax feedline to the shack runs horizontal and parallel to the
beverage instead of running along the forest floor? I am thinking of
keeping the RG6 elevated to greatly reduce the opportunity of critters
to chew on it but I don't want to impact the performance of the
beverage.
They are challenging questions that are not covered in anything that I
have read. I would appreciate all of your thoughts and insights!
Tnx & 73
Bob, KQ2M
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