I have heard that these type of antennas are not quite ready for
prime time,
I suspect you're hearing that from companies who don't make OWL or LFA
type antennas.
it has been said to me that they are very sensitive to the weather
changing S.W.R. if it rains or snows.
A low Q (e.g. "broadband") antenna is inherently *less* Sensitive to
weather changing SWR. The OWL is simply an incremental improvement
on the OWA that has become the standard for HF monoband yagis over
the past 15 years or so. Low impedance feeds provide additional gain
with somewhat cleaner pattern than is possible with 50 Ohm feeds.
Several designers are using the OWL principle with feed impedance
between 12 and 28 Ohms depending on the feed/matching system they
choose. The 12.5 Ohm feeds are particularly attractive in that they
can be implemented with a folded dipole driven element for direct
50 Ohm connection.
LFA and DES (a "Moxon like" bent driven element) are newer designs
which trade mechanical complexity for additional control over feed
impedance and pattern. Again, there is nothing in those designs
that is "not ready for prime time" if the work is done carefully by
designer who understands the field and implemented by a competent
mechanical engineer for reliability. The biggest issue with bent
driven element designs (LFA and DES) is that they can't be modeled
accurately with NEC2 based software so many "shade tree" antenna
designers are unable to "verify" the designs or make their own LFA
and DES designs perform the same way in the computer and in the air.
Those who use commercial quality tools based on NEC 4 do not have
those problems.
73,
... Joe, W4TV
From: Joe Barnes <n4jbk@comcast.net>
To: towertalk@contesting.com
Sent: Friday, September 6, 2013 7:43 AM
Subject: [TowerTalk] OWL and LFA antennas
Does anyone have any first hand experience with these OWL and / or the LFA type
of beams? I am mostly interested in antennas for 6 and 2 meters. I have been
looking at antennas for what I feel is too long and I am ready to get some more
beautiful aluminum and stainless in the air to punish the atmosphere.
I have heard that these type of antennas are not quite ready for prime time, it has
been said to me that they are very sensitive to the weather changing S.W.R. if it
rains or snows. I won’t stay up too late worrying about snow here in Florida
but it has rained here before.
I don’t mind at all trying something new but I don’t want to stick my head into
the noose if there is actual evidence saying that these type of antennas are flawed in some
really noticeable way that will make me regret putting them up there.
Thank you for your help,
Joe N4JBK
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