[Skimmertalk] Miniwhip Antenna questions

[dd5xx at web.de]

Hi Mike (W0MU),

as John already explained, I'd suggest to read following articles. Pieter-Tjerk de Boer, PA3FWM (=owner/developer of www.websdr.org) has explained how those antennas work and how grounding affect the successful use.

http://www.pa3fwm.nl/technotes/tn09d.html
http://www.pa3fwm.nl/technotes/tn07.html

After reading this you certainly will understand also that "too high" is not as good as one would expect. "height" of E-field antennas is: the difference between the active part inside the mini-whip and the conductor you have grounded it. Just remember simply for better understanding: one pole (the upper one) is the PCB inside the small mini-whip antenna and the other pole of your antenna is the conductor level where you grounded the mini-whip (bottom one). I did some tests on my own and I can acknowledge that the best height in my test example was 4-5m above "ground" which the antenna electrically sees. Before I had it on 6-7 or even 8 meters. The antenna played better on 4,50m height. It was mounted on a fiber glass pole. When you use a metal mast be sure to mount your mini-whip ABOVE (!) the metal part or you won't succeed. This is a very important point: the antenna has to be positioned ABOVE the top end of your metal pole.

I am not sure which antenna you purchased, but the original mini-whip from PA0RDT is shipped with a detailled instruction manual which is easy to understand. There is also a table printed with different heights and the appropriate signal levels expected. The most important part of such antennas that work mostly with the E field is (as already mentioned many times before):

- keep it away from metal parts or any sort of conductors
- install it away from your house where you have lots of equipment radiating E fields
- do not even try to install inside your house or next to it, you will get dissappointed for sure

About the "grounding" part: I am using HIGHFLEXX7 coaxial cable in conjunction with this grounding clamp shown here in the following link (scroll to the bottom of the page, you will see the grounding clamp)
http://www.wimo.de/coaxial-cable_e.html

Here is the installation manual for such a coaxial grounding clamp:
http://wimo.de/download/Erdungsschelle-montage.pdf
 
You will need of course the grounding clamp that will fit for your coaxial cable. Some others advice to "bury" the coaxial cable into ground. Other say it's just enough to even lay it on ground that's enough. I have tested a lot with my mini-whip and my conclusion was that the performance of this antenna is really affected by good antenna position and correct grounding. 

Hope this helps. Wish you good luck

73 de
Saki, DD5XX




Gesendet: Freitag, 09. Februar 2018 um 17:28 Uhr
Von: "John Ackermann N8UR" <jra at febo.com>
An: "W0MU Mike Fatchett" <w0mu at w0mu.com>
Cc: skimmertalk <skimmertalk at contesting.com>
Betreff: Re: [Skimmertalk] Miniwhip Antenna questions
I just got one of those yesterday as well.  As I understand the theory of operation (same as other active voltage probe antennas) the antenna works against the grounded mounting mast or other conductor that's tied to a ground rod at the base.  Without that grounded element, it doesn't hear anything (and I've verified that with my Clifton Labs version).  The coax shield can serve as the grounded element, BUT you need to connect it to a ground rod underneath the antenna.  Otherwise it searches for ground all the way back to the shack and picks up lots of noise along the way.

I may be mounting mine to a wood fence post, and plan to use an F connector grounding block (commonly used for cable/satellite TV) tied to a ground rod underneath the antenna.

As to height above ground, I've heard different recommendations.  Jack Smith K4ZOA at Clifton Labs believed that 10 feet was plenty high enough.

73,
John
----

On Feb 9, 2018, 10:55 AM, at 10:55 AM, W0MU Mike Fatchett <w0mu at w0mu.com> wrote:
>I received my miniwhip yesterday.  I was reading the instructions which
>
>seem to be out of date.  My miniwhip is enclosed in a pvp case so I
>assume that it is intended to be mounted as is.
>
>The instructions also say to mount it as high as possible.  I am
>curious
>as to how high others are placing this?  It also talks about keeping it
>
>away from metal and grounding it to the mast. What if I just screwed it
>
>on to the side of the house or used a pvc mast.  Would I want to run a
>ground wire up to the bnc connector at the bottom?
>
>W0MU
>
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