Vic, I don't know how to model. It's on my bucket list. However, my
personal opinion is that while modeling may give a general starting
point, all bets are off once the antenna - especially an indoor antenna
- is actually put in place. You've got a point about Italy not exactly
being "west" of me. In fact, IZ2GRG bears 55 degrees. But this still
bodes well for the Omni Angle in that it's omnidirectional and did a
heck of a job on rescuing his signal from a fixed doublet looking the
wrong way. This just points out one more nagging constraint we
antenna-restricted hams have to deal with: the direction our homes
face!
To offer one more nugget from my inventory of sometimes weird solutions
to being antenna-restricted: My attic doublet is always up and ready
and connected to a 6 way antenna/transceiver coax switch. I have two
more coax cables running outside and usually, I put up one of my other
"non-permanent" antennas which is always vertically polarized -- either
a PAR EndFedZ or a 40-6 meter EFHW also vertical. My third antenna is
a 53 foot random wire at 28' that terminates in a 9:1 BalunDesigns UNUN
and it's outside and "stealth."
But the 44' doublet in the attic clearly and
consistently outperforms everything in my arsenal except the new Omni
Angle which has been interestingly competitive as noted.
I have no idea how the Omni Angle would work indoors, in an attic for
example. Frankly it has such a small footprint and is so light and
rapid to erect that I probably will never bother to try it there.
However, it could easily be installed in an attic or even near the
ceiling in a room. This is because of the easy way it assembles and
disassembles; not a problem assembling it around and between the attic
framing. And at 2.5 lbs I suppose a simple plant hangar in the ceiling
would hold it up easily.
In closing, I consider myself extremely fortunate to have found antenna
solutions that allow me to enjoy enjoy QRP to the fullest extent. I
wish everyone else the same good fortune. And Thank God for the
invention of collapsible fiberglass poles! Where would we be without
them??
73,Stan WB2LQF
On Thu, Sep 26, 2013 at 03:21 PM, Vic K2VCO wrote:
> Stan,
Interesting. I did a quick EZNEC plot of the pattern of a 44' doublet
(close to a full wavelength) at 30' on 18.07 MHz and didn't see any
deep undefineds in the horizontal pattern. But in the direction of
Italy from NY it is down about 5 dB from the maximum gain in the E-W
direction. I recently modeled the 'cobweb' antenna, which is a
'square' dipole similar to the Omni-angle configuration; it had a
maximum gain of about 2 dB less than a dipole and would be down an
additional 1.4 db in the direction of Italy.
So my guess is that about only 1.6 dB of the difference between the
dipole and the Omni-angle antenna came from the patterns. The rest
could be attributed to the location of the doublet in the attic and
the dropped ends (I didn't model this, but I suspect it has an
effect).
On 9/26/2013 11:46 AM, stan levandowski wrote:
Hi Vic. My 44' doublet is in my attic, arranged as a flat top for
24' and then drooping
straight down at both ends. The antenna is almost exactly 30' above
the earth. It is fed
with 14' of 450 ohm ladder line straight down through a slit in my
ceiling and into a
linen closet where it meets up with an SG237 autocoupler. This keeps
the autocoupler out
of the winter cold and summer heat of the attic. From there I have a
run of nice "clean"
50 ohm coax to my second story "shack" This attic doublet
arrangement is nearly 4 years
old and has served me exceedingly well on 40 through 10 meters,
inclusive. I only run 5
watts CW at all times simply because I love QRP and I love CW and
it's my "thing." The
frequency agility of the doublet/autocoupler combination has been
wonderful because those
of us in restrictive environments usually don't have room for more
than one, possibly two
"good" antennas. I have a very RF friendly attic in terms of no foil
insulation, no HVAC,
only PVC plumbing stacks, etc. Of course, there is some attenuation
but at HF I believe
(from what I've been able to research) that this attenuation is
frequently overstated
and often considered to be far worse than what it really is. In my
experience, the
"worst" penalties that follow an attic (or any indoor) installation -
RF exposure
notwithstanding - are skewed radiation pattern and "house noise."
i
By comparison, the Omni Angle when this video was made was at 27' -
3' lower than the
doublet's flat top section. That was 15' above the lower deck + 12'
up on the Jackite.
The Omni Angle was "facing" E-W in the sense that the "front" wire
portion was pointing in
that direction; the attic doublet was pointing in the same E-W
direction. Of course, we
can all agree, I'm sure, that this information doesn't help all that
much in comparing
these two antennas because the drooped attic doublet had some
vertical component and most
assuredly some skew in its pattern + as another Lister pointed out,
on 17M there are lobes
on the doublet.
But here's what I think is important to know: For those of us (and
we're probably an
increasing number in today's world) who can't enjoy "antenna freedom"
this Omni Angle
represents another option and a darn good one from my experience of
the last 3 weeks. In
my case, it fits the footprint of my deck. I can put it up on my 31'
jackite to about the
25' + 15' for the upper deck gives me 40' of height, clear of my roof
line, and away from
the attic "house noise."
My attic doublet is my overall favorite antenna and out of the
weather and is always ready
for me. It's earned me DXCC at the QRP level, QRP WAC, and I've
worked all states too.
It's gotten me to Japan from NY on 5 watts more than once. But this
Omni Angle also got
me to Tokyo on 5 watts just last week. So, based on my experience,
the Omni Angle is a
competitive antenna for a restrictive home QTH, for portable work
and, in my case, for
"stationary mobile" where I drive to a scenic rest stop, drop a
fiberglass pole into my
hombrew mount on my VW Bug, hoist an antenna that's significantly
better than a Hamstick,
and enjoy ham radio.
Hope this helps to answer your questions, Vic, as well as those of
other Listers with
antenna restrictions.
73, Stan WB2LQF
On Thu, Sep 26, 2013 at 12:33 PM, Vic K2VCO wrote:
How high was the 44' doublet?
How was it oriented compared to the Omni Angle antenna?
Is the doublet in inverted V or horizontal configuration?
I am finding this interesting because I am soon moving to an
antenna-restricted location.
On 9/26/2013 6:57 AM, stan levandowski wrote:
About 3 weeks ago, I learned about a new "miracle antenna" - I
usually dismiss such
nonsense because there *is* no miracle antenna. However, the
person who informed me is a
trusted, capable, educated ham and DXpeditioner who is not easily
impressed.
I still don't believe in "miracles" but this 2.5 lb, 7 by 4 foot,
easy up/easy down, no
tools required, easy-to-tune $99 new product by Dale Parfitt
[designer of the PAR End
FedZ series] offers a realistic alternative to those with severe
antenna restrictions,
attic installations, SOTA needs, and so on. It is easily mounted
on a Jackite or similar
fiberglass pole. Just put it on and slide it down until it's a good
friction fit.
The antenna is resonant for a single band ( choose: 20, 17, 15, 12,
10 or 6) and
additional matchboxes can be purchased for around $25 each.
I bought the 17 meter version and in two weeks of non-scientific,
casual A/B testing
against my 44' doublet, the Omni Angle has been equal or better on
receive the majority of
times and about the same on transmit. On receive it seems notaby
less noisy than my
doublet. It is horizontally polarized.
I don't want to create an antenna controversy here on proper
antenna testing techniques --
I seem to have a flair for doing that -- ;)
But I do want to pass along info on this new product which might be
very useful to those
of us who have to live with antenna restrictions or who need
options for effective
portable operations.
Here is a short Youtube video I cobbled together to demonstrate my
17 meter PAR Omni
Angle.
http://www.youtube.com/watch?v=JGTq4zVAW_w
73, Stan WB2LQF
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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