"field day" HF vertical project

[loosecannon]

hi all,

im looking for vertical antenna design ideas.
by that i mean different antenna designs that can be oriented vertically.

this antenna will have to be something that i can take apart, put in the bed of my pickup, and put together somewhat quickly by myself.

this antenna will be used on 11m, but for all intents and purposes, any design that will stand up without guys on 10m will work fine.

i will be mounting two brackets to the side of my truck, one on the side of the toolbox, and the other below it attached to the frame.

these brackets will hold a 10 foot mast and im hoping to put the antenna on top of the 10 foot mast and not have to guy it.

yes, i could build a simple sleeve dipole, but i was hoping there might be a more "exotic" design, something that might even provide a db or two of gain over a halfwave dipole.

im also hoping to avoid matching networks if possible (not a deal breaker), and i wont be using a tuner.

thanks in advance for any ideas or links.
LC

 

[W5LZ]

Probably one of the 'simpler' 'exotic' designs would probably be a 'J'-pole for 11 meters. Or even a little simpler than that would be a typical 5/8 wave mounted on that pole. That does get into a matching network/device, not all that difficult to make though.
That 5/8 wave antenna would offer some small gain over a 1/2 wave, the 'J'-pole won't (it IS a 1/2 wave antenna).
- 'Doc

 

[loosecannon]

thanks for the quick reply doc.

ive been looking at J-pole designs, but that 1/4 wave matching stub below the vertical radiator brings the overall length to close to 24 feet.
i guess 24 feet isnt too much, but it means id have to build the antenna out of aluminum instead of wire and PVC pipe. just more expensive.

wouldnt the 5/8 wave need ground radials? i forgot to mention in my OP that i dont want to use ground radials.


gee, have i put enough restrictions on this project yet? LOL

also, when i say im not so keen on using a matching network, im talking about having to build an L-C network in a box or something. i dont mind winding a coil and finding the tap point on it. just as long as once i find it, i can solder it and forget it.

thanks again!
LC

 

[office888]

There's no easy way to create an antenna that has that much of bandwidth spread.

 

[loosecannon]

i guess i could have worded that part better office888, what i meant was if someone found a design for 10m, that i would have no problem changing the lengths to work on 11 meters.

i really dont need more than about a 1 to 1.5 mhz bandwidth for a 2:1 SWR curve.
2mhz would be nice, but i really dont need it.
LC

 

[W5LZ]

Most of the impedance matching networks/devices I've seen used on 5/8 wave antennas have been tapped coils.
Depending on a lot of things, you might be able to get by with just using the vehicle for the 'groundplane'/radials/counterpoise, not much is really needed for 10 or 11 meters.
- 'Doc

For that 'J'-pole thingy, a nice long cane-pole and some wire along with an extension for that 10 foot mast might be possible. Sort of 'Rube Goldberg' it, but don't 'Esher' it!

probably didn't spell that right, but you get the idea...

 

[loosecannon]

well, i have decided to change directions,or should i say polarities.

ive decided to build an 11 meter Moxon beam antenna.

i just never considered that a horizontal antenna was an option for my situation, but since the purpose of this antenna will be DX contacts; the moxon fits the bill just right.

i ran across the moxon site while searching for designs, and was instantly intrigued. very cool little antenna design, and its a 50 ohm antenna!!!

my moxon will be made from a wooden center support plate with PVC through the center that will sit on top of the mast. this will allow me to turn the antenna by hand.

i will use wood for the "X" arms also, and use wire for the antenna itself.

this will allow me to take it all apart and put it in my truck bed.

one question i have is whether or not to use a "choke balun" at the feedpoint or not.
my plan is to run the cable straight back to the center and down the mast.
i was thinking i could make the choke on the PVC that attaches to the mast, which would make it about 2 feet back from the feedpoint.

any advice on whether or not its needed and how much it matters whether or not its right at the feedpoint or not would be greatly appreciated.

the first pic is a moxon that uses PVC for the "X" arms, but other than that will be quite similar to what i will be building.

the second is a pic of what a basic moxon looks like.

any and all moxon stories are welcome!
LC

 

[unit_399]

My attitude on things like this is.... If you're not sure something will help, but you know it won't hurt anything, then go ahead and do it.

In any case I would use the choke balun

- 399

 

[wavrider]

Moxon is a simple dipole, balanced radiator

Coax is unbalanced


Use a balun? 1:1 Current or at least wrap an RF choke/ugly balun.

Should perform well for you. Let us know how it turns out.

 

[loosecannon]

thanks guys.

sounds like the choke is the way to go.

it would be nice to just slip enough ferrite over the coax to make the choke instead of having to wind a choke with the coax.
will have to look into that.

i will be building this antenna within the next month or so, as soon as i finish my "all thread 1/4 wave mobile antenna" project.


i will post results when the antenna is done.
LC