Tom,
All you say is correct and anecdotal evidence is spotty at best and I
understand this. But sometimes some of the guys, being big DXers have insights
that I and many others dont have. Having worked for a few years in an EMC
environment and a few years in a metrology lab I know that there is a lot more
to measurements than just having a piece of test equipment ... are we doing the
measurements correctly, is the equipment calibrated so that the date is
accurate and reliable? Can we even afford the equipment in the first place. I
for one being retired can not purchase an analyzer or even an FSVM so this was
the next best thing.
I often rely on the RBN to pick up spots and then record the data and can do
A/B comparisons but that requires you to have both antennas up at the same time
and separated by some distance (the far field would be great) but most of us
dont have this capabilities. I think I have said this before (it wasnt just
flattery on my part) your web site has many topics that would be a great loss
to the community should they go away for any reason.
This 20M dipole that I modeled (if I have modeled it correctly) appears to have
low takeoff properties that are only exibited by a few antennas on TB (19deg)
again if I have modeled it correctly. The RDF is not as good as some and the
impedance is terrible but strictly as a receiving antenna and assuming you can
actually get the 19deg TOA it would make a great receive antenna for the
restricted space set.. say the guys with the inverted L FCP antennas.
The antenna also seems to (again if modeled correctly) work fairly well on all
of the bands 20 and above for transmitting and has nice TOA on these bands.
WIth correct matching it could make some guy just starting out or with
restricted space ( an apapartment dweller maybe) a means to stay active in
their senior years when they cant keep up with a house.
and Tom its because of the CFA and EH antenna that I am asking the questions..
I am skeptical of the data that I have..
I will be glad to provide to anyone that wants it.. the information that I have
gleaned from eznec...
Jim
http://www.qsl.net/wa3mej/index.htm
----- Original Message -----
From: "Tom W8JI" <w8ji@w8ji.com>
To: PaulKB8N@aol.com, wa3mej@comcast.net, topband@contesting.com
Sent: Friday, September 21, 2012 2:58:17 PM
Subject: Re: Topband: Vertical dipoles in the real world
> I put up a short vertical dipole for 40M. It is 25' tall and has top and
> bottom X-shaped capacitive hats that are 42.5" square with a perimeter
> wire
> attached. The lower capacitive hat is about 6' above the ground.
>
> While the antenna is resonant just under 9 mHz, it works very well on
> both
> 30M and 40M. My "go-to" antenna on 40M is Double Zepp about 90' on a
> side. I frankly did not expect this short vertical dipole to be
> competitive
> with the DZ, yet it was!
Hi Paul,
How high was the DZ? What direction was it oriented compared to the
reporting stations? What is the feed system?
We really need articles describing ways to reasonably compare systems. There
is a small helical magnetic loop antenna that was in an eHam article and is
on U-tube that, if we believe the video, has well over 10 dBd gain!! The
CFA, the EH antenna, the Isotron, the CTHA antenna, and the list goes on and
on.
It might not be about what is right with antennas being evaluated, but what
isn't right or detailed with references.
73 Tom
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|