Thanks, Richard and Paul for answers about Beverage

Here's another one, if you (or anyone) wants to chime in:
There are about 4 paragraphs in the Antenna Book about Moxon design.
Again, in contrast, lots of chatter about it on the newsgroups and on
the air:
Is this a viable alternative to larger yagis and quads?

Specifically, there is an Optibeam OBW10-5. It appears to have a broad
front lobe. But, it also appears to have a lower visible profile, a
plus for the neighbors.

Is it worth consideration?

John
AB8O

On Thu, 17 Aug 2006 15:18:44 -0400, jawod wrote:

Is it worth consideration?

Hi John,

I'm only vaguely familiar with the design. The English seem to like
elaborate wire designs with lots of crenellations. I don't recall any
consistently negative or even occasional negative comments about Moxon
designs. On the other hand, they seemed to asked about more than they
are the subject of user's comments.

You might want to pick up a copy of "HF Antennas For All Locations,"
by Les Moxon, G6XN, RSGB.

73's
Richard Clark, KB7QHC

The ARRL Antenna modeling course includes the Moxon.
I kind of visualize the elements to be analogous to top hat tuned
parts of a two element Yagi.

I did not receive any Moxon examples in my copy of EZNEC but I am
confident it would model it OK.

I don't recall the feed details.

de W8CCW John

On Thu, 17 Aug 2006 15:18:44 -0400, jawod wrote:

Thanks, Richard and Paul for answers about Beverage

Here's another one, if you (or anyone) wants to chime in:
There are about 4 paragraphs in the Antenna Book about Moxon design.
Again, in contrast, lots of chatter about it on the newsgroups and on
the air:
Is this a viable alternative to larger yagis and quads?

Specifically, there is an Optibeam OBW10-5. It appears to have a broad
front lobe. But, it also appears to have a lower visible profile, a
plus for the neighbors.

Is it worth consideration?

John
AB8O
John Ferrell W8CCW

On Fri, 18 Aug 2006 01:01:02 GMT, John Ferrell
wrote:


I did not receive any Moxon examples in my copy of EZNEC but I am
confident it would model it OK.

LB Cebik has some stuff on Moxon rectangles online.

Owen
--

I looked it up in my course materials. It has a balanced feed of 50
ohms. A very broad front lobe with a high front to back ratio. I
believe you could consider it on par with a compact (short elements) 2
element Yagi. Structurally, I think the "tails" are a bit of a problem
compared to other forms of shortening.

It is difficult to compare Quads to anything else.
Quads always look good on paper because they are essentially a pair of
antennas that are efficiently coupled. They are challenging to build,
install & maintain due to the three dimensional construction.

I have not built one (yet?)...
de W8CCW John

On Fri, 18 Aug 2006 01:01:02 GMT, John Ferrell
wrote:

The ARRL Antenna modeling course includes the Moxon.
I kind of visualize the elements to be analogous to top hat tuned
parts of a two element Yagi.

I did not receive any Moxon examples in my copy of EZNEC but I am
confident it would model it OK.

I don't recall the feed details.

de W8CCW John

On Thu, 17 Aug 2006 15:18:44 -0400, jawod wrote:

Thanks, Richard and Paul for answers about Beverage

Here's another one, if you (or anyone) wants to chime in:
There are about 4 paragraphs in the Antenna Book about Moxon design.
Again, in contrast, lots of chatter about it on the newsgroups and on
the air:
Is this a viable alternative to larger yagis and quads?

Specifically, there is an Optibeam OBW10-5. It appears to have a broad
front lobe. But, it also appears to have a lower visible profile, a
plus for the neighbors.

Is it worth consideration?

John
AB8O
John Ferrell W8CCW
John Ferrell W8CCW

I modeled the Moxon example (EZNEC) at 20 meters and 40 ft elevation
with no big changes. When I allowed the "tails" to hang down it kind
of lost all resemblance to the original model.

with On Fri, 18 Aug 2006 01:01:02 GMT, John Ferrell
wrote:

The ARRL Antenna modeling course includes the Moxon.
I kind of visualize the elements to be analogous to top hat tuned
parts of a two element Yagi.

I did not receive any Moxon examples in my copy of EZNEC but I am
confident it would model it OK.

I don't recall the feed details.

de W8CCW John

On Thu, 17 Aug 2006 15:18:44 -0400, jawod wrote:

Thanks, Richard and Paul for answers about Beverage

Here's another one, if you (or anyone) wants to chime in:
There are about 4 paragraphs in the Antenna Book about Moxon design.
Again, in contrast, lots of chatter about it on the newsgroups and on
the air:
Is this a viable alternative to larger yagis and quads?

Specifically, there is an Optibeam OBW10-5. It appears to have a broad
front lobe. But, it also appears to have a lower visible profile, a
plus for the neighbors.

Is it worth consideration?

John
AB8O
John Ferrell W8CCW
John Ferrell W8CCW

On Thu, 17 Aug 2006 15:18:44 -0400, jawod
wrote:
Is it worth consideration?

I built one for the lower 3 MURS channels, and it works great. I put
it in my attic and the environment there brought down the VSWR
enabling it to function well on 2 meters. It works better (in the
direction it is more/less pointed) than my j-pole, and has a very good
front to back ratio.

Here are the design parameters I used (1/8 inch brazing rod):

CM Moxon antenna for MURS
CE
GW 1 1 -0.0962827 -0.00107657 8.78982 -0.00153852 0.000570162 8.78696 0.0015875
GW 2 9 -0.00153852 0.000570162 8.78696 0.000136935 0.000391379 9.50055 0.0015875
GW 3 1 0.000136935 0.000391379 9.50055 -0.0966646 0.000614526 9.49849 0.0015875
GW 4 1 -0.128867 -0.000352607 9.49837 -0.263769 -0.00132972 9.5011 0.0015875
GW 5 9 -0.263769 -0.00132972 9.5011 -0.264979 0.000746241 8.78833 0.0015875
GW 6 1 -0.264979 0.000746241 8.78833 -0.126962 -0.00066876 8.78845 0.0015875
GW 7 17 0.915355 -0.608882 9.49961 0.915743 -0.607934 7.97677 0.0015875
GE 0
FR 0 33 0 0 144 0.5
EX 0 2 5 0 1
RP 0 31 73 1001 0, 0, 3, 5, 10000, 0
EN

--John

John E. Davis wrote:
On Thu, 17 Aug 2006 15:18:44 -0400, jawod
wrote:

Is it worth consideration?


I built one for the lower 3 MURS channels, and it works great. I put
it in my attic and the environment there brought down the VSWR
enabling it to function well on 2 meters. It works better (in the
direction it is more/less pointed) than my j-pole, and has a very good
front to back ratio.

Here are the design parameters I used (1/8 inch brazing rod):

CM Moxon antenna for MURS
CE
GW 1 1 -0.0962827 -0.00107657 8.78982 -0.00153852 0.000570162 8.78696 0.0015875
GW 2 9 -0.00153852 0.000570162 8.78696 0.000136935 0.000391379 9.50055 0.0015875
GW 3 1 0.000136935 0.000391379 9.50055 -0.0966646 0.000614526 9.49849 0.0015875
GW 4 1 -0.128867 -0.000352607 9.49837 -0.263769 -0.00132972 9.5011 0.0015875
GW 5 9 -0.263769 -0.00132972 9.5011 -0.264979 0.000746241 8.78833 0.0015875
GW 6 1 -0.264979 0.000746241 8.78833 -0.126962 -0.00066876 8.78845 0.0015875
GW 7 17 0.915355 -0.608882 9.49961 0.915743 -0.607934 7.97677 0.0015875
GE 0
FR 0 33 0 0 144 0.5
EX 0 2 5 0 1
RP 0 31 73 1001 0, 0, 3, 5, 10000, 0
EN

--John
I'm sorry, I know what MARS is...what is MURS?

John
AB8O

On Fri, 18 Aug 2006 08:52:18 -0400, jawod
wrote:
I'm sorry, I know what MARS is...what is MURS?

MURS (Multi-User Radio Service) is an unlicensed service using the 5
frequences 151.820, 151.880, 151.940, 154.570, 154.600 MHz. The FCC
permits a maximum of 2 watts (TPO) on these channels but allows the
attachment an arbitrary gain antenna (with height restrictions).
Since repeaters are not allowed, you can think of it as something akin
to 2 meter simplex. As a result, I feel that this is a much more
serious unlicensed service compared to FRS.

It is my experience that the upper 2 frequencies are used mainly by
businesses (Costco, Walmart, etc) and the lower 3 are pretty much
dead. For this reason, the antennas that I have constructed are
geared more for the lower 3 frequencies.

See http://www.provide.net/~prsg/murs_faq.htm for more information.

--John

My 6m antenna is a Moxon. I built it because it seemed to be a good
tradeoff over a 2 element yagi, I hear the gain is within a dB or so of
a typical 2 el yagi but the front-to-back is very much more (for a
relatively broad-banded design); the element tips are bent in to
enhance the coupling between the elements and ensure a proper phase
relationship to get good front-to-back.

Mine is very small and light, modeled F/R around 50-50.5 is 25dB or
so, real F/B is s7/inaudible on my FT-857D, for what it's worth. (Not
much, I know. I've moved out of the apartment and into a house with a
backyard so maybe I can make some non S-meter based measurements). I
think it's worth considering vs. a 2 element yagi for HF. You'll
notice the enhanced directivity more than you notice ~1dB of gain.

On 6m, I was just looking for a very small, light array for an
apartment balcony antenna, and I liked how the Moxon stacked up. I
didn't really think the F/B was really going to matter until a security
light went on the fritz during a nice opening... the band was open out
west to Idaho, California, etc. The light was to my east. Pointing at
it; s9 noise, pointing away with the light in one of the back nulls,
nice band opening, no noise! Since it has a broad forward beam,
beaming off 10 degrees to get one of the -35dB nulls in the back on the
noise source didn't affect the desired signals much.

OK, so, dumb "I worked this cool stuff with it" anecdote aside, mine
does what it claims to, and I think it's worth considering, especially
for the lowest band on a compact multiband array. It makes it more
compact and increases the F/B ratio over a 2 element yagi. The extra
directivity makes it work very well as a beam psychologically and
emotionally, and there is a even a modest actual improvement to signal
to noise, moreso if you have a real noise problem in some direction and
like beaming the other! At the apartment, when that light wasn't
acting up, beaming to Europe put my building and the other closest
buildings off the back... there was a substantial reduction in the
noise floor when I was pointed that way...

I'm considering one for 20m now. I have permission to put up some
antennas at the new rental house but I don't have a ton of space. You
can make one with fiberglass fishing poles and wire that's quite light
and can be rotated with a TV rotator, though I wouldn't trust it to
survive a major gale. www.moxonantennaproject.com has a bunch of
pictures and descriptions. Mine is at www.n3ox.net/projects/sixmoxon.

73,
Dan