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Author Topic: 40m 1/4 wave vertical what to expect  (Read 2579 times)
AD9DX
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« on: March 09, 2013, 01:01:44 PM »

SO I just bought a DX engineering 1/4 wave 40m antenna, the radial plate and enough wire to put down 40- 1/4 wave radials.  I bought this so that I could try and work some new ones on 40 and anticipate that it will work well on 17m and 15m as well.  Anyone have any tips or experience with DXing with a vertical?   
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EX, KC9TRM, KB9IRZ
N4CR
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« Reply #1 on: March 09, 2013, 01:39:59 PM »

I primarily have used a Cushcraft R8 vertical for the last two years. With that, I have worked just over 180 countries. There is a large portion of the planet around my antipode that this antenna just doesn't get to. I'll need a tower and a beam to get there.

I would not call 40 meters my favorite band for DX but a lot of people do spend almost all of their time on 40 meters. 20-10 seems to be more often the place to find DX, but they are daytime bands during this sunspot cycle.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
AD9DX
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« Reply #2 on: March 09, 2013, 01:58:38 PM »

I primarily have used a Cushcraft R8 vertical for the last two years. With that, I have worked just over 180 countries. There is a large portion of the planet around my antipode that this antenna just doesn't get to. I'll need a tower and a beam to get there.

I would not call 40 meters my favorite band for DX but a lot of people do spend almost all of their time on 40 meters. 20-10 seems to be more often the place to find DX, but they are daytime bands during this sunspot cycle.

I've gotten over 200 with my OCF dipole.  I am really hopeful that I can get into Asia with the vertical.  I can't put up a tower at my QTH. SO I am trying to squeeze the most that I can with this solution.  My next project is going to be homebrewing a yagi that I can put on a push up mast for 17 and 12. 
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N7WR
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« Reply #3 on: March 09, 2013, 08:08:55 PM »

I easily worked DXCC on 40 from the west coast using a 40 meter 1/4 wave vertical.  You should do fine from your QTH
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K8AC
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« Reply #4 on: March 09, 2013, 08:11:38 PM »

I use basically the same antenna on 40M, but homebrew, same number of radials.  I'm sitting at 294 confirmed and all zones confirmed on 40 CW.  I'm in NC, a tougher path to Asia than from your QTH, so with a bit of patience, you should be able to hear and work the Asians you need. 

73, K8AC
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AD9DX
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« Reply #5 on: March 09, 2013, 08:25:11 PM »

I use basically the same antenna on 40M, but homebrew, same number of radials.  I'm sitting at 294 confirmed and all zones confirmed on 40 CW.  I'm in NC, a tougher path to Asia than from your QTH, so with a bit of patience, you should be able to hear and work the Asians you need. 

73, K8AC

Great to hear! I wish I wasn't in HOA hell but I was inactive when I bought my house. I plan on making the antenna 35' so it will perform best on the CW part of the band. It it works on phone, great if not I won't really care.
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W9GB
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« Reply #6 on: March 09, 2013, 08:39:15 PM »

Quote from: AD9DX
My next project is going to be homebrewing a yagi that I can put on a push up mast for 17 and 12 meters.
Large number of articles and designs for a dual band WARC yagi in amateur literature, since late 1980s.  
Size is an advantage in using readily available materials.

K4NR, Dual-band (12-17) yagi
http://www.k4nr.org/k4nr/12-17-Yagi.pdf

W0JCS, QST April 1993
http://www.arrl.org/files/file/protected/Group/Members/Technology/tis/info/pdf/9304036.pdf
« Last Edit: March 09, 2013, 08:42:18 PM by W9GB » Logged
K0ZN
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« Reply #7 on: March 09, 2013, 11:08:43 PM »

Hi.

I have a homebrew 1/4 wave 40 M vertical over a radial system of 103, thirty seven ft. radials. It is directly fed with about 120 ft. of LMR-400. The performance on DX is outstanding. I have yet to find a big DX pile up that took very many calls to break. Typically, one or two calls will get a response (at legal limit). The antenna is in the middle of my back yard, well away from the house out in the open. The longer the path the better it seems to work in terms of competitiveness. There is a down side: it is, or can be, depending on local factors/moisture levels, etc, pretty noisy on receive. This is typical of verticals, especially ones with a good ground wave signal.....you can hear every power line or other man made noise source with in 30 miles ! (at least it seems like that at times!)  I know the antenna has a very low radiation angle because I have worked some "long haul" ground wave "DX" with it pushing 35+ miles (the other station also had a vertical). Having a separate well isolated, horizontal receive antenna may be well worth the effort depending upon the noise level/situation at your QTH. If you can't hear them, you can't work them!! On close in State side station, you will find times when the main radiation is too low and a dipole will do better....not unusual; under about 600 miles my horizontal antenna is often the better performer....as theory says it will be.
When the single hop skip gets out to 1,200+ miles the vertical is almost always much better.

You will get good results with 40 radials, but if you are willing to make the effort, I think there actually is a marginal improvement (that seems to exceed the theoretical) by
increasing the radials to 60 to 75.  I clearly overkilled the radial system, but I would do it again as this antenna is flat out amazing at times. I had this antenna at a
previous QTH and the performance there was every bit as good which is why I rebuilt it at this QTH.

You will NOT get especially good results on 15 M because the main radiation lobe is at a very high angle around 45 degrees. (either model it or check out the pattern plots of a 3/4 wave vertical in the ARRL Antenna Book) It would make an excellent satellite antenna on 15 m !!  ....this is not to say you can't make contacts, etc. but MOST of your radiation is going to be at an angle that will not reflect. Unless you plan to put an autotuner  or matching network at the base, the feedpoint impedance on 18 Mhz is going to be "quite ugly" for direct coax feed and a very high SWR.

Bottomline: a good vertical is a pretty labor intensive antenna if you do it right, but the results are very gratifying. Unfortunately, most hams, especially those who
complain about poor vertical antenna performance, don't/can't/won't put in a truly effective/efficient radial system....and then get marginal results. Remember, the
radial ground system is literally the other HALF of a 1/4 wave vertical monopole antenna so minimizing ground losses is very much worth the effort.

Good luck.  73,  K0ZN
« Last Edit: March 09, 2013, 11:16:34 PM by K0ZN » Logged
K1WJ
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« Reply #8 on: March 11, 2013, 12:49:19 PM »

On 40m with 40 1/4w radials should work real good, more in the clear the better, - would not expect too much out of 17m or 15m. 73 K1WJ David
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W5WSS
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« Reply #9 on: March 11, 2013, 09:00:36 PM »

The ground mounted 1/4 wave vertical with a flat radial system symmetrically installed is really good relative to longer range Dx work.
The antenna will be very competitive to the Horizontal dipole installed up at 1/2 wave high, and superior to lower horizontal Dipole heights.
Most of the radiation will be returned to the feed point when the radials are just on top or slightly within the thatch of the grass turf and shallow.

I used a slightly elevated vertical base height like 5ft above the surface, and sets of two radials per band that were sloped downwards from 5ft traveling opposite each other to insulated anchors and even then the system worked very well in my estimation.
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W3HKK
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« Reply #10 on: March 14, 2013, 04:15:34 PM »

How high was your  horizontal antenna for 40m?
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AD9DX
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« Reply #11 on: March 15, 2013, 03:18:08 AM »

How high was your  horizontal antenna for 40m?

Right around 30'. It is a OCF dipole 90' on the short side 180' on the long side.
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EX, KC9TRM, KB9IRZ
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