[NLRS] Re: 1296 Rhombic

Thu, 13 Jun 2002 08:34:25 -0500

If you have sidelobes that are 1 db or so down then why not skip the
termination that reduces the back lobe and have a symmetric pattern. The
rotor would only need to turn 90 degrees if you could accept 1db down....
I have turning radius issues that it could solve.

----- Original Message -----
From: "Dayton Johnson" <[email protected]>
To: "J Craswell" <[email protected]>
Cc: <[email protected]>
Sent: Wednesday, June 12, 2002 9:22 PM
Subject: Re: [NLRS] Wait a sec - 1296 Rhombic

> Hello to those interested
> See the current issue of " ATV Quarterly". MY 440 Mhz Dual Rhombiod  is
on  the
> cover of the magizine and the  article with the construction details with
> pictures and
> some of my experiences with this Great Antenna
>
> J Craswell wrote:
>
> > Hi Jerry Bob and others:
> >
> > Well I haven't built one so take this with a big grain of salt.  BTW
have
> > you?  I'm done a little research and follows are some of the
particulars.
> > #1 the measured results at the Central States.  In my opinion 17 dBi+ is
> > nothing to sniff at.  If your putting up an antenna for gain (That is
the
> > goal, right?) what beats this for the same amount of scratch?  I think a
lot
> > of us would like to hear about a design with lots more gain (as you say)
I
> > don't know about the issue of "noise" in reference to the termination
> > resistors.  Perhapes you have a comment and I don't understand that
problem
> > if there is one?  There are some other things to consider as Bob and
others
> > pointed out.  Wind loading and "birds."  I might be off track but I
thought
> > one of the benifits of the Rhombic was the loosness of it's design?
The
> > yagi elements at 1296 are pretty touchy as I recall.
> >
> > In response to your pattern comments.  Having a better pattern to null
out
> > signals off the sides etc might be important for 20 meters where your
trying
> > to avoid signals in a pile up but at 1296?  Me?  I'll bank the 17 dBi
gain
> > and take the odd pattern and hope to hear an unexpected station or two.
BTW
> > I've included some other Quotes and messages from the fellow who
designed it
> > and his comments about it's performance vrs M2, KLM and Rutlands make it
> > sound like a pretty good bet.  Along with that is a "snip" from a fellow
who
> > uses stacked Rhombics for EME on 432.  To be honest that sort of
practical
> > display is what sells me.
> >
> > BTW the fellow who really sold me on the Rhombic (in general) was Ed
Addey
> > of Desert Voices fame who built one aimed at Kuwait and was heads above
the
> > Yagi and Log folks at the "big time" stations.  I think the fellows he
> > worked with the 5 watt packsets were particularly impressed or perhaps I
> > should say astonished.  I know I was.  He (along with Dayton) was fond
of
> > saying that the only antenna to touch the Rhombic is a parabola.  Maybe
I
> > might be the victim of propaganda, but I don't think so.
> >
> > 73 de Jay W0VNE
> >
>
> -------------------------------------------------------------------------
> > >Has anyone seen details on the rhombic mentioned above?  He seems to
> > >have attained 17dBi with what would appear to be a lot less work than a
> > >35 element loop yagi!
> > ---------------------
> > >I remember watching some white haired ol' weasel who, with a dual
rhomboid
> > >antenna, kicked butt in the 1296 MHz antenna gain competition at the
1996
> > CSVHF
> > >Society gathering in Bloomington, Mn. You might take a gander at:
> > ------------------------------------
> > > Steel Bill, Hi  this is Dayton w0ozi
> > > The Dual Rhomboids for UHF  are quite small about 6 wavelengths long
and
> > built
> > > on wood boom, so mounting them on tower or mast puts the  ground many
> > > wavelengths. Unlike one thinks of , in the HF or even VHF the
dimensions.
> > the
> > > ground reflection is not is part of the operation.
> > > The antenna is very Hi gain on major lobe(  about 5 degrees), it is
quite
> > broad
> > > band and works fine for SSB.  From by experience, it will beat
anything
> > out
> > > there with exception of parabola.
> > > Dayton Johnson w0ozi
> > -----------------------
> > 1296 MHz    Gain dBi
> >  W0OZI Dual rhomboid HB 17.3
> >  KB0PYO M2 35 el Commerical 16.6
> >  W3XO Short backfire HB 14.6
> >  WA2VOI Narda 15RH Commerical 13.8
> > * WA5VJB 10 el yagi, Reference Antenna HB 13.5
> >  W6OAL 11 turn helix HB 12.4 dbic
> >  WA5VJB 9 el Moonrabbit HB 12.1
> >  DJ9HO Dual quad/reflector Commerical 11.3
> >  DJ9HO Dual feed loop/refelector Commerical 10.7
> >  N8KWX Dual coffee can HB 9.7
> >  W0UC Create LP Commerical 9.1
> >  K9FYV 6 el End-fire HB 8.0
> >  W6OAL Yagi 6 el w/VJB feed HB 7.5
> >  N8EHA Conical Sprial Commerical 4.7
> >  K9FYV Conical Sprial Commerical 2.5
> >  K9FYV Log periodic Commerical .5
> > --------------------------------------
> > Hi Bernie:
> > I've been trying to send you a reply, but don't know how to use my
computor.
> > I'll try again with my 12/3 message.
> > That QST pix has stirred up phone calls, mail and the vhf reflector
internet
> > activity.
> >
> > My rhomboids have used 800 ohm terminations. Some of the reflector
comments
> > on their generating noise I have seen and while probably valid. I'd
build
> > one and try it. The gain has proven more important from my experience.
> >
> > I built my first one for 70cm FSATVfour years ago. The original
inspiration
> > was prompted by an artical in 73 magizine, July 77, Pg24. It worked so
well,
> > outperforming th M2, KLM, aand Rutlands other use around here for ATV.
> >
> > I have since rescaled my design for 910 and 1265 and could mail the info
if
> > you forward a mailing adsress. The 1265 version is what we tested at
CSVHF
> > antenna measurements range and is pictured in QST.
> >
> > Hope this reachs you and is of help.
> >
> > 73's W0OZI Dayton Johnson ------ Submissions: [email protected]
> > Subscription/removal requests: [email protected] Human list
> > administrator: [email protected]
>
> --------------------------------------------------------------------------
> > 432 MHz Rhombic Antenna Design Jack Albright K0WOW - June 1977
> > Last fall Jack, K0WOW copied our EME signals with a 4 dB converter using
two
> > stacked rhombics. The dimensions of these rhombics are shown in the
> > following figure. The design is based on work done by VK3ATN (World
above 50
> > MHz., QST. Jan. 1968) and K0MQS on 2 meters. The rhombics were stacked
> > approximately 2 wavelengths apart and composed of #18 copper clad wire.
A
> > universal stub was used for matching. K0MQS has tried stacking up to 8
> > rhombics and says that a 0.9 wavelength is about optimum.
> >
> > _______________________________________________
> > NLRS mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/nlrs
>
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