Another option is to broadside a pair of DHDL (AA7JV/TX3A) antennas
(also known as the bowtie, D-KAZ, and other names that merely describe
alternate physical configurations, but the electrical principle is the
same). The DHDL is effectively a pair of anti-phased terminated loops,
which themselves are phased verticals. It's an elegant design in that
the phasing is inherent to the antenna, no need for an external phasing
system. IV3PRK published a paper that investigated broadside DHDLs (pg.
6) among other configurations:
http://www.iv3prk.it/user/image/..-rxant.prk_tx3a.pdf
12.24dB (80m spacing) to 13.35dB (110m) RDF......
whether you can erect DHDLs on your property (wooded) may be tricky.
Thoughts: Base insulated metal supports (part of the vertical run) on
each end in the TX3A style "delta" or right angle triangle
configuration, or supports in the center of each "loop" in the style of
the D-KAZ (isosceles triangles).... or you could use a couple trees
supporting the top wire runs w/ a rope "break" in between. I used the
latter configuration for a rather large (355ft total span) DHDL for
2200m in my obsession to reach a 10dB RDF on that band:
http://no3m.net/2020/09/2200m-double-loop-receive-antenna/
using a slightly different configuration to maximize the enclosed loop
area, which increases gain.... might not sound important on 2200m, but
when the DHDL gain is around -60dBi and located in a very quiet rural
area, every dB counts to ensure the weakest signals are not lost and
unrecoverable.... I regularly hear VK4YB on that band (including some
good runs this summer), sometimes the only station in NA despite being
in the "east".
GL in your quest for RDF!
- Eric NO3M
On 10/19/20 4:56 PM, Kenny Silverman wrote:
Thanks Frank & Dave,
The spacing and stagger I mentioned just doesn’t seem to work (the rear and side lobes and ultimately the RDF)
regardless of the phasing. If I’m going for max RDF to EU that fits in my property the best scenario appears to be
two 540’ beverages spaced ~20’ and staggered 70’. I can fit that pair in my lot and the RDF is
~11.5 dB. A 580’ single beverage has an RDF of ~9.83 dB.
I know my beverage plans will change as I plan out the station but at least I
have some options.
Regards , Kenny K2KW
On Oct 18, 2020, at 11:37 AM, donovanf@erols.com wrote:
Hi Kenny,
A single 580 foot Beverage is an excellent 160, 80 and 40 meter antenna.
I still have three of them (NE. S. W) even though I also have 8-circle
arrays for 160, 80 and 40 meters.
I've never used a pair of staggered Beverages with 350 foot broadside
spacing, these are ideas based on no specific experience with your
proposed configuration.
The offset shouldn't matter as long as you compensate for it by selecting
optimum unequal length transmission lines to feed the Beverages,
creating the equivalent of 110 feet of free space phase delay (about 100 feet
of RG-6). Your favorite antenna modelling program will help you select
the optimum transmission line length, but its not critical at all.
Alternatively, you could use a close spaced pair of staggered Beverages
that improve the front-to-rear ratio, but the beamwidth of the main lobe
isn't narrowed like a broadside pair of wide spaced broadside Beverages.
Good luck!
73
Frank
W3LPL
From: "Kenny Silverman" <kenny.k2kw@gmail.com>
To: "160" <topband@contesting.com>
Sent: Sunday, October 18, 2020 3:20:17 PM
Subject: Topband: Phased staggered beverages
My new house has 6 wooded acres in roughly a square. For EU, I was hoping to get a pair of phased 500’ beverages
spaced 350’ apart. To do that, one of the 2 beverages will be 110’ in front of the other due to the
lot-line orientation. Regardless of the phasing I’m modeling, the side and back lobes are not to my liking. Is
the 110’ forward stagger too far? I can get a single 600’ beverage to Eu which has a marginally worse
RDF (0.35 less) than the not-perfect-staggered-pair but is much simpler and takes up less land.
How much RDF increase does it take to be audible?
Regards , Kenny K2KW
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