On Thu,9/11/2014 1:24 PM, Guy Olinger K2AV wrote:
In Jim's second linked PDF, he makes reference to W6GJB's (Glen)
ground as being very poor, presumably because these measurements show
so much more loss than "average" ground in the model.
I said the ground was very poor because it is mountainous, very rocky.
The question is what do you have to do to get the model to hand you
13.5 dB differentiation with those same changes in height IN THE MODEL.
Note that the lowest field strength was with the feedpoint on the
ground, which turns the coax between there and the choke into a single
radial laying on the ground.
The assumption is that Glen's ground is abnormally bad. Suppose Glen's
ground is very ordinary and speaks for a majority of space challenged
situations. What then?
Note to self: "It's the ground losses, stupid!"
Yup.
Think about how the vertical on the roof at K9OR avoids at least some
amount of ground losses.
In the 60's I had a trap vertical over raised radials 1 foot up from a
copper roof on a 3 story row house. It worked GREAT. The same antenna
later turned into a ghastly dummy load near the grass after I moved to
the suburbs and had to put it somewhere behind the house where it
couldn't be seen.
Yes, two great examples of "If I Can Put My HF Vertical On My Roof,
Should I?" with the answer being a definite yes, as predicted by my work.
73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
