[NLRS] Wait a sec - 1296 Rhombic

Wed, 12 Jun 2002 13:41:49 -0500

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

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>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
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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]
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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.