[Lowfer] antenna location

[k2ors at verizon.net]

Doug,

  Jay and I were talking about locating  e-probes a few days ago - Jay pointed out something I hadn't thought about  - the impedance of an e-probe is so very high that it is impossible to isolate the feedline from the antenna.
Thus with any e-probe the coax is part of the antenna circuit, you just can't get any significant isolation by using ferrite chokes on the shield etc compared to the hundreds or thousands of megaohms input impedance of the e-probe a ferrite choke on the coax will present an insignificant impedance.

A longer (or higher) run of coax will have a major effect on the performance of the antenna.



73 Warren K2ORS
          WD2XGJ
          WD2XSH/23
          WE2XEB/2
          WE2XGR/1


Dec 10, 2010 06:40:12 PM, lowfer at mailman.qth.net wrote:

===========================================

Years ago, when I first started using an active e-probe antenna for
LF/VLF receiving, I placed it on a ten foot TV mast attached to a vent
pipe on my roof. The results were underwhelming, as noise (QRM) from
devices inside my house was quite strong. It wasn't long before I
moved my antenna to a spot in my yard about 50 feet from my house,
which produced much better results, and that has been my receive
antenna location for the various antennas that I have used over the
years. A couple months ago, we had a metal roof installed over the old
asphalt shingles. It just struck me today that the new metal roof
might provide an RF barrier for the QRM. I wouldn't mind having a
second receive antenna in place. Do you guys think I should try
putting one on my roof again, or should I just find another spot in my
yard?

73,
Doug KB4OER
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