On 12/4/2021 3:09 PM, kq2m@kq2m.com wrote:
1) Is that a formula specific to beverage antennas for determining
length? Or should I used the standard dipole formula 1/2 wavelength =
468/ f?
I've always seen 550 ft as an ideal length for 160. I have one of that
length, another 50 ft shorter.
2) What is the effect on a terminated directional beverage (terminated
at the back end that runs downhill at an 8% slope? If the maximum of
the lobe is at say 15 degrees on flat ground, does the lobe maximum
drop to an even lower angle? Or does the lobe change? or both?
3) Same question but with the beverage now running uphill at a 5%
slope.
NI6T, W6GJB, and I all have rather irregular terrain. Our Beverages
work just fine. In the words of NI6T, a LONG time 160 op who lives
DEEP in a ravine but has something like 240 countries on topband, "Any
Beverage is better than no Beverage." Gary's and Glen's terrain is
very dense like yours.
4) Same question but with a 20' high "Hump" in the middle? as the
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.
Don't worry too much about height. Mine start off 5-6 ft high, get
low, run downhill for a while, then elevated to 15-20 ft over a
ravine, eventually terminating near the top of the ravine.
6) What happens when you have 4 ground mounted receive verticals with
that large 5' boulder taking up of the space in the middle of them?
What does that do to the pattern?
Study W3LPL's excellent talks at Dayton on a half dozen or so RX
antenna types. He notes that some RX systems are bothered by nearby
surroundings (trees, etc.) while others are not. This a "must study."
7) 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 However, they
are on the side of a steeply sloping hill so that the first row is at
820' asl and the 2nd row is in the same direction but at 800' asl.
How might that affect the pattern? (for purposes of this question
ignore the impact of ground being "ledge" rather than soil.
8) 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 40 meter wire beam before the performance of either the
transmitting antennas or receiving antennas starts to degrade? A
formula for distance in wavelengths would be most helpful.
Mine (two reversibles using DXE hardware) cross each other within 30
ft of my 120 ft tower. They work.
9) How far apart fractions of a wavelength do the beverages have to be
from each other before their performance starts to degrade?
10) What is the impact on beverage receive performance if the RG6 Quad
Shield coax to the shack instead of running along the forest floor,
instead runs horizontal and parallel to the beverage? I am thinking
of keeping it elevated to greatly reduce the opportunity of critters
to chew on it but I don't want to impact the performance of the
beverage.
Some of my RG6 runs along a wood fence and then is elevated to clear
my driveway and enter the shack, but most of it runs on the ground.
It's the direct burial type that has the sticky goo in it, that
varmints don't seem to like.
11) Is there any performance advantage if I were to terminate the
beverage with a ground rod and radials in that standing water on the
hilltop? Or does it not make a difference?
Study the texts on Beverages. There's a terminating resistor that
serves to match it. Beverages DO work better with termination, but
again, any termination is better than no termination. At PJ4A, the
ground is volcanic rock, making driving a rod difficult. The guys
terminate them with a few short radials. More might be better.
Finally, I have read about many preferred beverage lengths for 40, 80
and 160 but few if any seem to be based on an established formula to
calculate their lengths. What formulas and multiple of wavelengths
would you use and why?
My EU/VK Beverage works all the way up to 20M -- I used it a lot to
copy EU when all I had for TX was a high dipole. They get narrower as
they go up in frequency.
12) How many wavelengths on 40 is too long and how many is too short?
Same question for 80? Same question for 160. I know that these
answers vary by band which is why I am asking.
I have a pair of VE3DO loops spaced 5/8 wavelength for 160, steered
with an NCC-1 box. They work well when something hasn't fallen on
them.:) They are written up on my website, k9yc.com/publish.htm
They are challenging questions that are not really covered in anything
that I have read. I would appreciate all of your thoughts and
insights!
It's worth doing more reading. The ON4UN book has a lot on Beverages
and other RX antennas. W3LPL and N0AX recently authored a QST piece on
Beverages.
73, Jim K9YC