6 meter beam - OT

[Gary Smith-2]

I find I have a place for a 6 meter beam. I don't have one but would
like to make one if feasible. Does anyone know of good plans for a 6
meter beam that would be realistic to make?

Might as well use the 6M ability of the K3


Thanks,

Gary
KA1J
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[Svend Spanget]

Hi Gary.

DK7ZB (http://www.qsl.net/dk7zb/start1.htm) has a lot of good designs.
I recently discovered the new promising design of G0KSC
(http://www.g0ksc.co.uk/) and I plan to change my DK7ZB yagis to the
design og G0KSC.

Vy 73 de Svend, OZ7UV

Gary wrote:
I find I have a place for a 6 meter beam. I don't have one but would like
to make one if feasible. Does anyone know of good plans for a 6 meter
beam that would be realistic to make?


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[Geoffrey Mackenzie-Kennedy]

Hi Gary,

What length of boom would be practical for you?

In Canada I used homebrewed yagis on 6m from 1956 onwards, singles and
stacked, which were not difficult to build, and if I still have the
construction detail for the 6 el yagis on 24ft booms I could send it to you,
if 24ft is not too long for you. I opted to run the elements through the
boom rather than use saddles to mount the elements.

The ends of the elements should be plugged, otherwise they might and usually
do "sing" when the wind blows.

Beware of 6m, there is no known cure once you become addicted :-)

73,

Geoff
GM4ESD (ex VE2AIO etc)



Gary Smith KA1J wrote on Thursday, March 18, 2010 at 6:18 AM



>I find I have a place for a 6 meter beam. I don't have one but would
> like to make one if feasible. Does anyone know of good plans for a 6
> meter beam that would be realistic to make?
>
> Might as well use the 6M ability of the K3


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[W7GJ, Lance]

Hello Gary,

Welcome to the Magic Band!  The K3 is a GREAT radio for 6m!  You can compare some
of the most popular 6m antennas on my web page here:

http://www.bigskyspaces.com/w7gj/6mTable.htm

Hams all around the world have had very good success and repeatability building 50
ohm yagis designed by YU7EF:

http://www.yu7ef.com/

If you have any questions or need dimensions for a specific element diameter that
is different than the options listed, Pop YU7EF probably already has a table
showing the proper element lengths for the material you are using.  He also has
dozens of photos that he can send you, showing the approaches that others have
used in constructing the antennas.  Especially detailed construction photos
(applicable to any of the YU7EF designs) are shown by ON4KST on how he constructed
the EF0610:

http://www.yu7ef.com/ef0610.htm
http://www.on4kst.com/10el50/

I have completed 6m EME contacts with a number of stations around the world using
those homebrew antenna designs, and at least two of the 100w stations I have
worked were using the EF0607 (7 element yagi):

http://www.yu7ef.com/ef0607.htm

I hope you have something whipped up by the beginning of June, when Es season will
begin in earnest ;-)  You can keep tabs on the current 6m Es activity by
monitoring the map on this popular chat page:

http://www.on4kst.info/chat/login.php?band=7

GL and VY 73, Lance


On 3/18/2010 6:18 AM, Gary Smith wrote:

> I find I have a place for a 6 meter beam. I don't have one but would
> like to make one if feasible. Does anyone know of good plans for a 6
> meter beam that would be realistic to make?
>
> Might as well use the 6M ability of the K3
>
>
> Thanks,
>
> Gary
> KA1J
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

--
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: [phone]   URL: http://www.bigskyspaces.com/w7gj
LIVE MESSENGER CHAT: [hidden email]
2m DXCC #11, 6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the Magic Band EME email!
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[w2bvh]

I've been using the "Route 66" OWA antenna by W4RNL (LB Cebik) and it's worked out quite well for me. The driven element is a dipole and there is no matching structure (gamma / tee / balun) required. Just type in W4RNK in google, establish an account for the site and then go to http://www.cebik.com/content/a10/vhf/66.html.

GL & 73,
Lenny W2BVH


----- Original Message -----
From: "Gary Smith" <[hidden email]>
To: [hidden email]
Sent: Thursday, March 18, 2010 2:18:45 AM GMT -05:00 US/Canada Eastern
Subject: [Elecraft] 6 meter beam - OT

I find I have a place for a 6 meter beam. I don't have one but would
like to make one if feasible. Does anyone know of good plans for a 6
meter beam that would be realistic to make?

Might as well use the 6M ability of the K3


Thanks,

Gary
KA1J
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[K6LMP]

If you're looking for a relatively compact six meter beam antenna, consider a three element quad.

Dimensions are available at http://www2.mmae.ucf.edu/~ssd/ham/quadcalc.html, which has a Java calculator for various quads, based on formulae developed by the legendary antenna guru,  L. B. Cebik, W4RNL, SK.

I think the three-element quad has by far the most bang for the buck (gain vs. size) for a single six meter antenna.  Free-space gain on Cebik's "high gain 3 element" design is 9.34 dB on a boom of approximately 8 feet, or 0.4 WL. It has impedance at resonance of 55 ohms, which means it's a piece of cake to match to the transmitter. Since the quad is a balanced antenna, you do need a choke balun to restrict current flow in the coax shield. (I use the Elecraft balun kit.)

For comparison, a 2 element quad, with a boom length of about one meter, has only 7.07 dB gain, and although the four element quad gives you an additional 0.8 dB gain with the additional element, it comes at a high price -- the boom is almost 30 feet long!

For a Yagi to achieve gain similar to a three-element quad, you need to double the boom length.  If you look at the marvelous spreadsheet that VE7BQH posted a bit earlier, you'll see that single Yagis of about the same boom length as the three-element quad offer free space gain of only about 5.5 to 6.5 dB, and Yagis with about 9.5dB have boom lengths of roughly 1.1 wavelengths, more thn twice as long as needed for a comparable gain quad.

A quad can be configured for either horizontal polarization (for SSB) or vertical (for FM), depending on whether you feed it on the bottom or side. For ease in mounting the feed point balun and cable, I position my quad as a "diamond" with the spreaders pointed vertical and horizontal, and the wires at 45 degree angles. With the feed point at the bottom, this antenna has horizontal polarization, which is the setup I use for weak signal SSB work. (My computer modeling shows that at antenna heights of roughly 6 meters above ground, the "diamond" configuration very slightly improves antenna performance relative to having the spreaders at 445 degree angle and the elements aligned horizontally and vertically.

I have sightly modified Cebik's design and created a 3 element six meter quad with slightly more gain (9.56 db) and even better SWR of 1.05:1 (51.2 ohms +j 2.2) with the antenna cut for 50.130 mHz resonant frequency to center on the frequencies most used in VHF contesting. Here's are key measurments for my 50.130 mHz quad antenna:

Dimensions:   Radiator spreader 1.082 meters, position 0.00
                Reflector spreader 1.16 meters, position -1.02 meters
                Director spreader  1.05 meters, position +1.50 meters
                total boom length 2.52 meters (8.25 feet) total wire needed about 75 feet.

Real-world (not free-space) performance is outstanding. Positioning the antenna 6 meters or more above ground is ideal, and provides a maximum gain of about 14.5 to 15 dB at a takeoff angle of 10 to 30 degrees, depending on height (the higher, the better).

Construction methods are readily available online from many sources, or you can email me offline if you'd like details on how i built mine. You can make the boom from any material, but the spreaders must be non-conductive for RF (which eliminates metal unless you use insulators to connect shorter segments) and also eliminates carbon fiber shafts. DI was surprised to learn, when researching this antenna, that carbon fiber is basically an insulator for DC, but a good conductor of RF.)

I also have a web page under construction on this antenna, located at: http://web.me.com/lewphelps/K6LMP/6_meter_quad.html.

BTW, if you're really serious about 6 meter work, you'll want to invest in Elecraft's  PA-6 6 meter pre-amp, since the receiver design for the K3 is great for lower bands, but has less than optimal gain on 6 meters. You'll also want to get the transverter/receive antenna module for easy attachment of the PA-6. Definitely worthwhile.   But a really good antenna is essential, too.
 
Lew K6LMP

On Mar 17, 2010, at 11:18 PM, Gary Smith wrote:

> I find I have a place for a 6 meter beam. I don't have one but would like to make one if feasible. Does anyone know of good plans for a 6 meter beam that would be realistic to make?
>
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[Dave, G4AON]

Lew Phelps K6LMP wrote "If you're looking for a relatively compact six
meter beam antenna, consider a three element quad."
--------------------
Or a four element, see my web pages for the dimensions of a portable 4
element quad http://www.astromag.co.uk/quad/
It might not be what you want, but it's nearly the season for portable
operating on 6m and this type of antenna is both cheap and easy to make
so the link might help others.

73 Dave, G4AON
K3/100 #80


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[W8JI]

> For comparison, a 2 element quad, with a boom length of
> about one meter, has only 7.07 dB gain, and although the
> four element quad gives you an additional 0.8 dB gain with
> the additional element, it comes at a high price -- the
> boom is almost 30 feet long!
>
> For a Yagi to achieve gain similar to a three-element
> quad, you need to double the boom length.  If you look at
> the marvelous spreadsheet that VE7BQH posted a bit
> earlier, you'll see that single Yagis of about the same
> boom length as the three-element quad offer free space
> gain of only about 5.5 to 6.5 dB, and Yagis with about
> 9.5dB have boom lengths of roughly 1.1 wavelengths, more
> thn twice as long as needed for a comparable gain quad.

Actually not. A three-element yagi on a 0.4 wl boom can
easily have 9.4 dBi gain in freespace. I just confirmed that
by pulling up the model for my 40 meter 3-element yagi
antennas, which models at over 9.4 dBi in freespace with a
0.4 wl boom.

There is virtually no difference at all between a quad and
yagi for gain. How they work is more how they are optimized
than anything else. There is very little difference between
them. The quad trades H-plane beamwidth for E-plane
beamwidth, and that difference goes away even more as the
antenna is made longer or placed over earth. Either can be
slightly better, or slightly worse, depending on height when
optimized. When one is "messed up", it will naturally look
worse.

http://www.w8ji.com/quad_cubical_quad.htm

73 Tom

 

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[W7GJ, Lance]

Hello Gary,

Just be careful comparing information you receive from different sources!  That is
why we put together the VE7BQH comparison table, with all antennas listed in FREE
SPACE GAIN COMPARED TO A DIPOLE (DBD).  Gain figures look unbelievably good when an
antenna gain in dBi is compared to a conservative dBD value.  Many antenna
performance calculating programs also include up to 6 dB of extra gain for the peak
GROUND GAIN LOBE when the antenna is aimed on the horizon over flat perfectly
conducting ground.  Be sure you compare apples to apples or you will be very
disappointed in whatever antenna you build.  Good luck and VY 73, Lance

On 3/18/2010 5:03 PM, Lew Phelps K6LMP wrote:
>
> For a Yagi to achieve gain similar to a three-element quad, you need to double the
> boom length.  If you look at the marvelous spreadsheet that VE7BQH posted a bit
> earlier, you'll see that single Yagis of about the same boom length as the
> three-element quad offer free space gain of only about 5.5 to 6.5 dB, and Yagis
> with about 9.5dB have boom lengths of roughly 1.1 wavelengths, more thn twice as
> long as needed for a comparable gain quad.

--
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: [phone]
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the MAGIC BAND EME email reflector!
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[K6LMP]

Great construction notes, Dave!

However, I don't see the advantage of the longer boom and fourth element required with your design. With the 3 element design I described, free space gain (as modeled with cocoaNEC) is virtually the same as your four element design, while boom length is only about 8 feet vs. your 12 feet, and your best SWR is 1.26:1, compared with 1.02:1 for the three element antenna. The only appreciable benefit I see to the longer boom is a better f/b ratio (about 27 dB vs. about 17 for the smaller antenna).

Lew K6LMP

On Mar 18, 2010, at 10:55 AM, Dave, G4AON wrote:
[snip]
> --------------------
> Or a four element, see my web pages for the dimensions of a portable 4
> element quad http://www.astromag.co.uk/quad/

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[K6LMP]

OK, point well taken. I was comparing dBi (isotropic antenna) to dBd (dipole), and that is not appropriate. However, the gain figures I quoted are free space calculations.  

To correct the comparison, the free space difference is 2.15 dB

(reference: http://www.digi.com/support/kbase/kbaseresultdetl.jsp?id=2146)

thus, the 8-foot boom Yagis in the table would equate to about 7.65 to 8.65 dBi gain, which is still a 1 to 2 dB less than the free space gain of the described quad, on an apples to apples comparison.

sorry for not getting the comparison right the first time. the differential between Yagis and quads is less than I originally stated, but still non-trivial.

Of course, if you're building arrays for EME work, the Yagi is much more practical. For a single antenna, I still think the quad is preferable.

Lew K6LMP


On Mar 18, 2010, at 11:30 AM, Lance Collister, W7GJ wrote:

> Hello Gary,
>
> Just be careful comparing information you receive from different sources!  That is
> why we put together the VE7BQH comparison table, with all antennas listed in FREE
> SPACE GAIN COMPARED TO A DIPOLE (DBD).  Gain figures look unbelievably good when an
> antenna gain in dBi is compared to a conservative dBD value.  Many antenna
> performance calculating programs also include up to 6 dB of extra gain for the peak
> GROUND GAIN LOBE when the antenna is aimed on the horizon over flat perfectly
> conducting ground.  Be sure you compare apples to apples or you will be very
> disappointed in whatever antenna you build.  Good luck and VY 73, Lance
>
> On 3/18/2010 5:03 PM, Lew Phelps K6LMP wrote:
>>
>> For a Yagi to achieve gain similar to a three-element quad, you need to double the
>> boom length.  If you look at the marvelous spreadsheet that VE7BQH posted a bit
>> earlier, you'll see that single Yagis of about the same boom length as the
>> three-element quad offer free space gain of only about 5.5 to 6.5 dB, and Yagis
>> with about 9.5dB have boom lengths of roughly 1.1 wavelengths, more thn twice as
>> long as needed for a comparable gain quad.
>
> --
> Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
> P.O. Box 73
> Frenchtown, MT  59834  USA
> QTH: DN27UB
> TEL: [phone]
> URL: http://www.bigskyspaces.com/w7gj
> 2m DXCC #11/6m DXCC #815
>
> Interested in 6m EME?  Ask me about subscribing to the MAGIC BAND EME email reflector!
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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[Gary Smith-2]

Wow, many great replies!

I am going to make an antenna for 6M, just seems like the right thing
to do. I am somewhat height challenged as the house is a one story
and the rotor is on a roof mount. Realistic height is probably 25-30'
tops to the top of the rotor. On the other hand, the house is
essentially on the ocean with the salt marsh behind me as my radial
bed for my vertical antennae. The soil is 20' above sea level and
it's essentially flat for all directions except for a 500' hill top
1+ mile away.

I used to have a 3 element Gem Quad which worked wonders and would
not be adverse to another quad but I'm not so sure I'd be able to
have it high enough on the rotor that it would clear the peak of the
roof.

I will read up on the different links you mentioned to me and see
which looks the most likely. I'll be using CW, not FM & SSB might be
an interest but of the last 1K entries in my log (other than
contests), I have maybe 3 SSB entries and the rest are CW. OK, 2 AM
QSOs as well.

Thanks to all who replied on & off list to my request, I might as
well use the tower for something and the RFI from my amp on 20 gets
into some oddball electronics here, barefoot 6M will not be a
problem.

Thanks!

Gary
KA1J

> I find I have a place for a 6 meter beam. I don't have one but
would

> like to make one if feasible. Does anyone know of good plans for a 6
> meter beam that would be realistic to make?
>
> Might as well use the 6M ability of the K3
>
>
> Thanks,
>
> Gary
> KA1J
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>

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