[TowerTalk] Questions on Low band receiving antennas in forests and wetlands along ridgelines and ravines.

[kq2m at kq2m.com]

Hi Jim,

Thank you for the reply and answers.

John, KK9A was kind enough to send me the link to the W3LPL/N0AX article 
as well as Frank's 2016 presentation at Dayton.  Excellent stuff!  Many 
of my questions were answered - so my list is smaller now.  :-)

I agree - any beverage is better than no beverage and sometimes when you 
have competing antennas "too close" to each other they still work well 
despite the common knowledge on the subject.  But not always.  I had 
very effective beverages ~ 20 years ago as well as great pair of phased 
40 meter EU beverages.  But since that time I have had massive severe 
chronic health issues which eliminated any possibility of traveling deep 
into the woods for the better part of 15 years.  And since that time we 
have also had at least a 10x increase in Deer Ticks.  Having had 
Ehrlichiosis and g-d knows what else, the ever-present ticks remain a 
concern.  So I was hoping to use some woods closer to me but the 
topography is extremely unkind to my receive antenna plans and my power 
lines and major league HV lines on 100'+ towers lurk at the edge of the 
property.

I remembered that K6STI's great AO program allowed me to model beverages 
based on ground conductivity and length for a given freq. and certain 
lengths as a function of wavelength produced much sharper pattern with 
good rear lobe suppression and lower wave angles, than others.  I have 
to find my old notes on that.

Tnx & 73

Bob, KQ2M

On 2021-12-05 04:56, Jim Brown wrote:
> On 12/4/2021 3:09 PM, kq2m at 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