Topband: RX ant-Frozen ground

[Lee STRAHAN]

When we at Hi-Z see deterioration it is often the output cable running to the receiver where the typical aluminum shield no longer makes great contact. Also if it's one of the Hi-Z Antennas amplifiers make sure you are seeing 4 to 5 Volts DC at the element or amplifier input. Foliage touching an element has often been the culprit as well. Once even a spider crawled across the amp terminals and the 5 volts killed it and left a partial short.  You just never know.
Lee  K7TJR

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of VE6WZ Steve
Sent: Wednesday, December 07, 2016 1:36 PM
To: topband at contesting.com
Subject: Topband: RX ant-Frozen ground

I’m wondering what experiences are out there regarding small vertical array, or beverage performance in the winter over frozen ground.
 
The reason for this question is that over the last 2 weeks or so, my HI-z (24’ vertical) SDR skimmer antenna at my remote QTH has shown somewhat diminished performance and a dramatic increase in AM inter-mod byproducts on 160.
During the somewhat hasty install of this antenna (the SDR “RBN skimmer” antenna was not considered an important part of the station) I had some trouble driving the ground rod for the HI-z amplifier and only ended up with about 3’ of copper pipe driven into the ground. During this past summer and fall the performance was good.
Winter has been here for a while. Last night it was -28 deg C. Today, that rod is now probably sitting in a block of solid ice. (ok, not solid ice, but the conductive dissociated ions from the native salts distributed within the soil are now locked in ice)
 
In truth I am not really concerned about this particular antenna, but I do plan to install an 8 circle array as well as some beverages  this summer and this problem got me thinking about making sure I have a “seasonally stable” ground system up here in the frozen north.
Some quick research points to potential frost depths ranging from 6’-8’ depending on snow cover and soil type. Perhaps driving deeper rods could help, but it seems to me that there will still be a seasonal change of consequence. Literature associated with various short vertical array products indicate that 3’-4’ rods should be adequate, but is this true in a northern climate?
For the most part, I could care less whether the array works in the summer…..it’s during our winter DX season that I want performance.
 
Perhaps a very carefully designed and symmetrical short ground radial system could stabilize things, but I know with phased rx vertical arrays this can be a big problem and cause phase imbalances. Perhaps on my beverages a small radial system at the termination would be helpful.
 
I am not new to rx antennas, having built and used numerous single wire beverages, reversible beverages and end-fire phased beverages as well as passive and active (Hi-z) phased vertical arrays at my home QTH, but have never “noticed” a problem.
BTW, it is possible that there is something else going on with my SDR antenna other than a ground problem, and I will be checking that out next time I’m at the station. However,  I think I’ll still want to consider the frozen ground impact even if there is something else going on.
 
Any experiences, measurements or ideas from those living in places where it snows a lot, you have something called a “block heater” for your car, and when you work outside you last about 5 minutes before your hands and toes are numb??
 
de steve ve6wz. 

 
Steve Babcock
Lead Geologist, Mature
TAQA North Ltd.
D +1.403.724.5147
M +1.403.870.0082
2100, 308 – 4 Avenue SW, Calgary Alberta Canada T2P 0H7


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