Antenna for 80, 40 and 30

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Does anyone know if a fan type dipole in an inverted vee configuration can be made for 80, 40 and 30 meters? And, if so, how the addition of other bands affects the performance over a single dipole. I have room for an full size 80m inverted vee hanging at about 35 - 40 feet from my tower. I would prefer a resonant arrangement, but my backup plan would be something like an OCF dipole (although I don't know if that will work on 30).

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Mark Erbaugh

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Posted 2 years ago

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Walt

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You can start with this site - and modify one of the other bands (like 20) to make it 30 meters.

http://www.hamuniverse.com/multidipole.html

A really good antenna analyzer is a must.   Also a pulley up the tree so you can pull your antenna up and down for lots of adjustments.

As for performance, you may need to learn the EZ NEC antenna program and model your final antenna.  Lots to do during winter.

Good Luck !
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WX7Y

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Yes it will work fine, There are lots of variables with wire length.

Wire type is a big factor, insulated - Non-insulated, solid or stranded and of course wire size and ground field under Antenna.

Start long on your wire lengths, and start with your longest element 1st (80 Meters) and work your way to the 30 Meter or what ever your highest band is when your tuning it and be sure each side is the same length.

Put as much distance as you have room for between (widest FAN) each wire length.


A good trick to use when ruff adjusting the wire length is to slide some heat shrink (about 2 feet long) over the wire then install the insulator and wrap the wire twice through in insulator to keep it from pulling through the insulator and then fold the wire back onto it self and slide the heat shrink down over the loose end ,use heat shrink size so it fits snug over both wires , To adjust frequency just add or remove wire length in or out of the insulator,


This will get you really close before you cut the excess wire off the ends, then adjust the next shorter set of wires the same way and lastly do your final element then check resonance on the longest wire and make sure SWR is about where you want it, when you get it tuned where you want it then cut some of the excess off and recheck it.
When your all done use GOOD UV resistant ties wrapped twice around the wire in a couple places along the Heat Shrink and it should hold for YEARS.


Myself I would put no less then 8 Fer-rite beads on the coax at the feed point of the fan Dipole to stop any RF Currents from coming back down into the shack.


Your mileage will vary but this has worked for me on MANY fan dipoles over the last 36 years


Bret

WX7Y
(Edited)
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Jimm

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Yes a fan dipole made of wires will work very well.  Each of the dipoles for 80, 40 and 30 can be made resonant.  The spacing of the ends of the dipoles from one another is critical at least a couple of feet apart.  The further apart the less effect one dipole will have on the resonant frequency of the other dipoles.  The band width of the dipoles will be fairly narrow with the 80 meter about 100khz and the others progressively wider.  Hope it works for you

73 Jerry W5RCQ  
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George Molnar, KF2T, Elmer

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Sounds like good answers. I am a fan of the OCF, too. Works best with tuner at feedpoint, but a good quality transformer works well.
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Luis del MOlino

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You only need to connect two dipoles in parallell because 30 meters is almost the third armonic of  the low part of 80 meters. (3.500 x 3 = 10.500).

You are not well centered on any of both bands, but not too much far away for the tuner of the 6000 series could'nt tune without any problem and the losses for not working with SWR =1:1 (in the coax) are very small in these bands (less tan 1 dB for normal coaxial lengths).

I am working so in 80-40 and 30 with only 2 dipoles for 80+40 in parallell. (I can tune it too in 17 and 12 meters). Do not forget to separate the ends as much as posible.

73 Luis EA3OG


 

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George Molnar, KF2T, Elmer

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The 40m dipole should perform well on 15m, too!
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Rob N4GA

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When you get past two legs on a FAN, tuning them all becomes a real challenge, even with a analyzer, because each one affects the others.

But like someone else said, you can get pretty close and your tuner can handle it.

Also, the wider spaced the fan, the better.

Fun trying to hang these beasts!

Good luck,
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Jay -- N0FB, Elmer

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Yo may want to look at the AlphaDelta DXCC fan dipole. You could add lengths to the 20 meter legs to get your 30 Meter resonance.

https://www.alphadeltacom.com/pg1.html
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k0eoo

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Hi Mark,

An 80m dipole fed with 600 ohm tuned feeders, at the center, will give you 80m through 10m with very low loss; I ran one for over 15 years.  For this to work well your operating station should be near an outside wall so tuned feeders can be run through a window or wall?  The antenna is also called a center fed Zepp and can be found in older ARRL handbooks.  You will need a balanced tuner as well... 

600 ohm line can be found at the following link:
http://trueladderline.com/w7fg-design-600-ohm-open-wire-feedline/

If you prefer not to use tuned feeders, an OCFD design can be fed with coax to a 4:1 Balun at the antenna feed point.  This works for harmonically related bands like 80, 40, 20, includes 17m but requires a tuner for 30m .  Losses are higher than with tuned feeders but  a pretty good match can be designed so the Balun losses are minimized.  

If you would like some antenna modeling help let me  know.  I've been modeling antennas for over 20 years, just send me the antenna dimensions or let me know what you need... 

Good luck, Dennis, k0eoo
(Edited)