[Rover] MOXON antennas

[Frank Alwine]

Hi Jacob - I've homebrewed a couple 2M Moxon's, 1 made out of 1/2" copper
water pipe and the other from 3/8" aluminum (the aluminum one was a 
replacement
for the copper one) and used them the first couple contests I roved.

At 2M they seem pretty easy to make with good/flat SWR.  3db beamwidth is
on the order of 90 deg. with a very deep null off the back (theory says 20+ 
db);
pattern is a cardiod shape.  The wide beamwidth is a great asset, as is the 
deep
null off the back if you've got loud stations behind you.  A single Moxon 
has about
as much gain as a pair of phased loops.  The wide beamwidth lets you get 
away
with turning it much less to work stations (and you can hear more stations 
that
you're not directly pointing at).  But you will have to turn it, unlike a 
loop; just
you'll be turning it less than a full-fledged yagi.

On the downside they are a little tricky to build mechanically, since the 
driven
element is a dipole and needs to be open in the center and insulated from 
the
boom if the boom is metal.  A good 5el 2M yagi will blow it (or even a pair) 
way
for directional gain, with much less mechanical/feedline complexity(in the 
case
of phased Moxons).  I ended up with a Directive Systems 5el yagi on a 6' 
boom
for roving.

BUT I remain a big fan of Moxons and hope to play with them more in the 
future.
I think a phased array of them would work great - esp. say for a fixed 
station to
cover a direction not often pointed in by the main antenna(s) - for exampe 
to the
north/northeast for a station in southern New England.

Another possibility for higher gain and mostly omni coverage is a Big Wheel.
If I remember correctly a Big Wheel has about the same gain as a single 
Moxon
but is omnidirectional...

Good luck with the antennas systems, and if you go with Moxon's I'd love to
hear how the work out for you (esp. if you phase them).

73,
Frank  KT1VT / FN34kp Vermont



>From: "Jacob Tennant" <k8jwt at adelphia.net>
>Reply-To: Rover's for VHF Contesting and Grid Square Collecting 
><rover at mailman.qth.net>
>To: "Rover list" <rover at mailman.qth.net>
>Subject: [Rover] MOXON antennas
>Date: Sun, 8 May 2005 14:18:23 -0400
>
>What is the feelings about MOXON antennas for a rover setup? Looking into 
>building one for 6/2/70 as in a single for 6meters, 2 phased for 2meters, 
>and 4 phased for 70cm.
>
>Since they are basically a 2 element yagi, how directional are they? Would 
>like to use the like a loop/squalo antenna.
>
>Jacob Tennant-K8JWT
>
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