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Author Topic: WHat is the Best 20 Meter MONO  (Read 1866 times)
NN2X
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Posts: 159




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« on: January 02, 2010, 03:54:01 PM »

I have decided on designing a 20 Meter system...I only have 45 FT tower..

My restriction on the boom is 44FT..(Due the close neighbors (Can have antenna swinging over their property)

Currently I am looking at M2 (44FT Boom), or Optibeam. Both of these manufactures have gains of + 8dBd..

If any one has any suggestions please indicate
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WB2WIK
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« Reply #1 on: January 02, 2010, 04:06:17 PM »

Check availability.

I like M2 and their monobanders are excellent.  Haven't used the Optibeam.

What is "availability" (delivery) for each?  

In some cases, beams can take months (and months!) to be delivered, this would be a guiding point of concern for me.

The Hy-Gain 205BA is another excellent contender, BTW...been around forever, works fabulously well...very strong antenna...check its availability also.
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K6AER
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« Reply #2 on: January 02, 2010, 09:44:38 PM »

My 4 element SteppIR monobander works very well on 20. It is also a monobander on 17, 15, 12, 10 and 6 meters.

It can be made into a 3 element monobander, 2 element monobander and a dipole monobander.

It can be bi-directional or 180 degreeded monobander with out moving the boom.

I have had mine up since 2003 in Colorado and it has been very reliable in the snow, ice, lightning and tornados.

Although, one drawback, the antenna is not cheep.
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G3RZP
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« Reply #3 on: January 02, 2010, 10:46:50 PM »

I find my 4 ele Steppir is at least as good as the 5 ele 205BA monobander it replaced, with the advantage of having 20, 17, 15, 12 and 10. It would be used on 6 if I had a rig for 6....

Worth the expense.
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VR2AX
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Posts: 586




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« Reply #4 on: January 02, 2010, 10:59:48 PM »

Have you thought how you will get the beam up on the tower? A 44' boom on a 45' tower will be a bit of a *monster* - and for 20m, 45' height is a bit low anyway. And they don't get up there by themselves!

The Hy-Gain 203BA only has a 16' boom, which might be worth a look, alternatively the German "ZX" range, which has a 20' boom for a 3-ele monobander. The ZX uses a gamma match, which can be a bit of a pain, the Hy-Gain have (I think?), split driven elements and a beta match, but I might be wrong.

Take a close look at the mechanicals, which will feature more prominently  than the electricals as time goes by.
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VR2AX
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« Reply #5 on: January 02, 2010, 11:32:14 PM »

BTW, if you have a neighbour's property close by, you want to make sure that when you rotate the antenna, no part of any element or boom intrudes into the air space which belongs to the neighbour's land. Otherwise you could be sued for trespass, and be subjected to an injunction.

Check the minimum distance from the centre of your tower to the closest points of your boundaries with neighbours' lands. Then compare that minimum distance with the turning radius specs of the antennas you are considering. a 20m beam will have reflectors 36' or even longer in length, on the far end of the boom, so when Pythagoras' theorem is applied you will find that you availale 'space' may shrink considerably.
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W7ETA
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« Reply #6 on: January 02, 2010, 11:59:33 PM »

You'll need a BIG rotator for a monster antenna.  Plus, you need an tower that will handle the wind load.

I've had great FUN with a tribander--bought it in the mid 80s.  It won't compete with bigger antennas on higher towers, especially when people run 10K amps.

Right now, putting up a good 20 meter monobander makes short term sense.

73
Bob
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NN2X
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« Reply #7 on: January 03, 2010, 04:45:23 AM »

K6AER, G3RZP, VR2AX, WB2WIK, W7ETA

Thank you all for the responses..

One more questioned to you all..I am assuming 20 Meters is the band to be on, if you just chose one band? Also, for the folks with the Steppir Antenna, what Band do you use mostly..

I agree with the comment 45 FT tower is to low, I am restricted, I thought of 17 Meters, (As myBand to go on)...But I believe it is still on and off..(Getting feed back from other Hams).Anyway, having a smaller boom on 20 meters won't help my restriction on height (I believe)..

But again, thanks all for your responses, it helps a million...
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KB9CRY
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« Reply #8 on: January 03, 2010, 06:36:43 AM »

Both are excellent. Your low tower height will negate any advantages between either antenna.

Plan on an amp and you'll be good to go.  Do not obsess too much with this setup since you can not even come close to "optimizing" (for that you need taller tower and probably a couple of beams mounted at different heights with the ability to phase them in and out with each other.

Personally I use M2 with great results and performance and life.
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AD4U
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Posts: 2157




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« Reply #9 on: January 03, 2010, 08:03:29 AM »

I think the M2 monobanders are the best yagis I know of.  The SteppIR antennas (IMO) cannot compete with the M2 antennas, because the SteppIR antennas cannot adjust element spacing, only the length of the elements.  This is a compromise.  The M2 monobanders are not compromised.  The element lengths and the spacing between them are optimized.

Dick  AD4U
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K9MRD
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« Reply #10 on: January 03, 2010, 09:35:10 AM »

<<<if you just chose one band>>>

If I had only one band, it would be 40 meters as 20 seems to close at night and 40 is wide open - frequently world wide.
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VA7CPC
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« Reply #11 on: January 03, 2010, 05:17:52 PM »

Quote
I agree with the comment 45 FT tower is to low, I am restricted, I thought of 17 Meters, (As myBand to go on)...But I believe it is still on and off.

If you go with 17 meters, you're locking yourself out of all contesting activity! 

And restricting yourself to a band with much lower activity than 20m.

And missing the PSK31 "watering hole" on 14.070 . . .

             Charles
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K6AER
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« Reply #12 on: January 03, 2010, 08:52:00 PM »

“I think the M2 monobanders are the best yagis I know of. The SteppIR antennas (IMO) cannot compete with the M2 antennas, because the SteppIR antennas cannot adjust element spacing, only the length of the elements. This is a compromise.”



The above statement reflects old school thinking. Element spacing is critical when you are trying to provide best gain and Front-to-Back ratio over the whole band while maintaining a decent VSWR. You will find that when the elements can be individually adjusted for resonance on each band over frequency, the element spacing is not longer a critical factor. VSWR is always low. The antenna can be adjusted for best gain, front to back pr configured to wider beam width or narrower beam width.

I have had 204 BA’s, Telrex 4 element, 3 element quads, KT34A and TH-7DX over the last 20 years. Each were good performers but you will realizes that total gain on all of the antenna is within .5 dB. The station will never hear the difference when you signal is S9+20. What you hear is the Front-to-Back and Front–to-Side rejection. The antenna that can provide better off beam signal rejection will enable you the hear DX in the colophony of the pileup.

A four element SteppIR has a boom that is 32 feet in length. Boom length has more contribution to gain than any other factor in yagi construction and design. Most four lement 20 meter yagis have about that length of boom.

I consistently have better than 24 dB front to back and 30 dB front to side rejection with the SteppiR on any frequency from 20-15 meters. Ten meter is a bit less.

The antenna is not cheap but like many well worth the investment.
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G3RZP
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« Reply #13 on: January 04, 2010, 05:56:18 AM »

I agree with K6AER about the Steppir. Worth the expense. I mainly use it on 18 and 24MHz, but that's because I am chasing countries on those bands - I have DXCC on 10,15 and 20! Although when KP1 comes on, any and all bands will see me chasing it as the last one needed for #1 Honor Roll spot.
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AD4U
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Posts: 2157




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« Reply #14 on: January 04, 2010, 06:11:23 AM »

Regarding the comments on the SteppIR that element spacing is not important.......

I did not know the laws of physics have changed so much since I graduated MS EE in 1971.  I guess one is never too old to learn something new.

I still think my home brew 5 element 20 meter monobander will whoop your similar SteppIR.

Dick  AD4U
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