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Dipole Question

K

kd-5-bgt

W9WDX Amateur Radio Club Member
Nov 10, 2007
1,176
92
58
Joplin Missouri area
I have been looking looking to install a dipole antenna for a HF station that I am putting together (hopefully very soon)

The antenna that I am looking seriously at is the Princton 80D

it is the antenna that is shown at the top of the page on this link

Associated Radio

I have done alot of looking at the property here and I just dont think that I am going to be able to flat top it ( I realize this is the prefered way to have a dipole set up and the higher off the ground the better ) ...so I am looking at an inverted V configuration for the antenna running Northeast to Southwest more or less direction...the balun will be set at 45 to 50 feet off ground ...and yes I will be running a tuner

So what I am asking is at what angle from flattop is the prefered angle in degrees to set up antenna? more or less of course....

I do know that a dipole such as the G5RV for inverted V prefered is more or less the same angle as taking a circle and cutting it into 3 equal parts or 120 degrees between the wires..

I do also realize that different types of dipoles (windoms,off center fed types have different characteristics for inverted V set ups)..so any ideas guys?

and thanks
 

don't really worry about the center angle. just get the ends up as high as you can. or put it up as an inverted L
 
Hi LA

An Inverted L is not a dipole.

For an Inverted V Dipole, the legs should both come down at 45 degree angles. Any other variation will start messing with the bandwidth, SWR and radiation patterns away from what any specs say as to how inverted V dipoles work.

I assume you're doing this for 80 meters. The legs are going to be around the 75 foot range. How high off the ground do you think you're going to be able get the bottoms of the legs? To achieve much of any height above ground of the bottom legs of an 80M IV....the center is going to have to be up pretty darn high. Leg bottoms low to the ground will also affect performance. Also, using a center-connector balun model for use with coax as feedline like the one you're looking at in the link, that's going to be alot of heavy coax up in the air. Most hams would use 450 ohm ladder line to feed a high-up center feed arrangement such as this to keep both feedline cost and especially weight down.

Take a look at horizontal loops before you do this. That's my choice in HF wire antennas. They cover all bands above (and including) the band it's cut for, are quiet on RX and increase in gain as you increase in frequency. They work all the way up to 6 meters at 50-54mhz with a good outboard tuner.

Good luck!
 
Hook,that is most likely what is going to happen ...but I was thinking there was a prefered angle ,seems I remember reading that somewhere..could be wrong though

7732...that is good reading on the G5RV,very interesting !!

Wire that antenna I linked to is supposed to be usable from 10 to 80 meters and 132 feet over all length,....they advertise to be able to use it either flat top or in an inverted V set up with a decent tuner..... I will give that loop antenna a good look as well...options are a good thing

I am not to sure how high the ends will be off ground at this time...as I said the balun will be around 50 feet..
 
An inverted V can use any included angle over 90 degrees.

The closer to flattop, the more the bandwidth and average height of the antenna itself.

The feedpoint at 50 feet will work fine for regional 80 meter contacts. The way that band has been this winter you could work much further.

If you have a tuner consider using balanced line all the way between the shack and feedpoint if you can pull it off.

That will allow operation on all bands 80 and above without the horrendous losses you will get with the antenna you are looking at. What you propose will be a dummy load on 40 metres due to extremely high coax losses with high SWR.

If the yard won't take a 125 footer even with the ends drooped you can cut it down to 100 feet centerfed with balanced line and a tuner and never see any difference if installed correctly.

Alternately, the last 20 or so feet of the doublet can bend down vertically. Watch the ends as they have very high voltages even at 100 watts.

Whatever way it goes up try for symmetry to avoid common mode current on the feedline. That will cause R.F. radiation where you don't want it like the shack and the neighbor's toaster.


Running a tuner INTO coaxial cable can be a giant waste of power unless it's only touching up the tuning. Usually any tuning touchup advantage is lost to tuner losses so you are back where you started in the best case situation.
 
I think you also might think about buying a spool of wire and making your own dipole. There's really nothing to it, it's simple. Figure about 122 feet will put it resonant somewhere around 3.850 Khz. If the center is at 50 feet or so, just get the ends up as high as is practical. The angle between the two legs isn't critical much at all. As 'flat' as possible is nice, but if it'll only fit if the legs are drooped a bit, do it that way. Those legs also don't have to be perfectly straight. They can be bent in several ways, and as long as those 'bends' aren't too close to 90 degrees, it'll work just dandy.
I'm a fan of using ladder line or parallel feed lines with a tuner and balun. Some tuners have a balun built in, some don't, and either way will work just fine. Using a fairly short run of coax (as short as possible) from the tuner to a balun just outside the house, then ladder line from there will also work and it'll make things a bit easier to get the feed line outside. ladder line isn't that big'a problem anyway, it's just different than coax. It has some benefits in that SWR on it just doesn't make a lot of difference, which is nice.
Using an 80 meter dipole on other bands is easier using ladder line (at least for me). It won't work well on all the other bands, but even so, it's better than not having any antenna at all.
I'm also a fan of using full wave horizontal loops. They are NOT just 'cloud warmers' by any means, don't be mislead! An 80 meter loop will do just dandy on most other bands, but like any antenna, there will be some frequencies that it and your tuner just won't 'like' very much. If you use ladder line, varying the length of that feed line will work wonders as far as that not 'liking' particular bands goes. You might be surprised.
- 'Doc


(If you can't get a 500 foot spool of wire for less than the cost of that commercially made dipole, I'd be very surprised! And being naturally cheap, I'd sure rather make a wire antenna than buy one.)
 
Well I have spent a good part of today (since I done my orginal post) talking to a few folks in the area about different types of dipoles for multi band use.

I failed to mention the multi band use in my orginal post :blink:

That is what I get for posting before my morning caffine intake :unsure:

But anyway...one of the locals here as informed me that he uses an off center fed windom type dipole and has offered to help me with a build. He is using his OCF for 80 to 10 and informs me that he is getting really good results with it.

And I am going to drop by his place and have a look at his antenna farm so I can get an idea of what to expect.....and the best part is all I have to do is buy the beer :D

oh yea !

Thanks for the replies,and keep em coming !! I am always open to any ideas


OK next question here.....does the dipole have to be run in a straight line?I have done some more looking around and I am discovering that I am going to have to run one leg almost north south and another leg more or less north east south west....Will this effect the tuning or performance drastically?
 
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Does it have to be 'straight'? No, it doesn't. You can make it into almost any 'shape' and it will still work. And like anything else, the closer you keep it to a sort of 'classic' shape the closer the performance will be to the 'classic' one. It can be tilted at any angle from horizontal to the ground, to vertical, to where the center is the lowest and the legs are pointed up. If you pick a reference point, then select a rotation axis, you can spin the thing in any direction you can think of. The two things to keep in mind are, the higher above ground/dirt the better. And, think of those 'legs' as being the (+) and (-) terminals of a generator. The further you can keep them apart, the more potential there is. Of course there are 'limits', but a lot of times those 'limits' are determined by where/how you have to put the thing up.

The people who can put up a dipole at the height and orientation that's considered the 'best', or 'classic', are sort of lucky. The rest of us have to make-do with less than what's considered 'classic' or 'best'. I've spent most of my radio time on the lower HF bands, and honestly can't think of a single time when an antenna I've owned was ever at a classical height/orientation. I've also used one or two that were in the 'best' position for what they were. Naturally there is a difference, but not one that can't be 'worked-around'. Just takes a little more time to wait for the 'right' conditions to happen for what I was trying to do. :) I've also used a couple of antennas of the "What the @#$$ is that?", or, "Why would anyone in their right mind do that?", variety. Surprisingly, a few of them worked! Would I recommend any of those kind? Not unless you were really desperate, or bored.
What it amounts to is that whatever you put up for an antenna doesn't have to stay exactly as you put the thing up. You can always change it later.
- 'Doc


(I think I'm in my 'right' mind. It's all the rest of you who aren't, most of the time!) ;)
 
Thanks!! ..I asked the question about it being straight because I have alot of trees...alot .... so finding a place where I can get a straight run for thye antenna is very limited because of limbs or other trees ...from the looks of this I am gonna have to break out the imagination to get this to work

One good thing about all the trees is I have plenty of places to hang the antenna from .All I have to do is find a spot that will work
 
Good old Antenna stuff!

I have to go along with Doc. You put up what you can get up and go from there.
Your going in the right direction it seems. Looking at your available environment and seeing what may work.
I have a few more things to ponder.
A. As you look around the plot count a few steps here and there...Lets say from your shack to the farthest tree or anchor point.
B. How far from there to the next farthest.
C. Highest point and it's relation to the others(scratch pads to map these out)
D. Your anchor points...How High...ie... if I can not get let's say 65ft from feed-point to anchor and only have 40 ft...can I get it up 30ft up and bend it down from there....
OH the possibilities are endless!...See Half Square antennas...Good ones!

My favorite get'um on and running antenna...

The Center Feed Double Zepp! or Center Feed Double Extended Zepp with TV Twin Lead or 450 Ladder line.
I have used both with good success.

A Folded Dipole using Twin Lead for legs(65ft each from center) and again Twin Lead or Ladder for feedline...

A Good Ground and a decent Tuner and Your up and running 80m thru 10m...and you will be shocked at who answers!

Like Doc. I've used squares(Loops) rectangles, triangles, "Multi-angles" with dangles, bends, and warps!...they do not have to be dead straight, they can have a little swag and droop, they don't have to be horizontal or vertical...
Most will be Horivertical...or is it Vertazonical???

My newest toy is 2 dipoles 58ft each side of center with 58ft spacing between them "Backfired" with 450 Ladder from shack .
Front dipole about 45ft at center and 25ft each end
Second about 30ft at Center...same ends
Using 3 ropes between tress holds the whole thing up

Reports from the group I chat with on 3.865 it is about 6 to 10 db better than a coax feed dipole at same height...
It also works great on 20/17m ...works Europe no problem from Ind.

Old saying though is Everyone is loud somewhere!
Good Luck
Enjoy
All the Best
BJ
 
The article is to long to put it here. I will give the web address where a lot of the questions here are answered. The antenna which is described will require an antenna tuner but can be designed to work from any band and as you raise frequency it has some gain. Look especially at the pacbell link there where they give figures of performance and gain of a dipole(inverted) as opposed to a flattop. The nice thing about the antenna is that it takes a lot less space than a classic dipole for any given band.
Two Loops 80-10 Meters
 
I've played with wire antennas a lot over the last year, a bunch of different types in any configuration possable. All of which worked "ok" From flat tops and inverted vees on the tower to strung up in trees to laying on the ground or layin on the roof. I made the same contacts with the diopole layin on the ground as I did 50ft up the tower "yes with a little less signal but not enough to cause a problem" Put up what you can and go have fun. The wire antenna that seemed to work the best for me was a full wave loop. It is what I compared all the other antennas too. Its not a pretty antenna just strung up in some trees in the back yard about 25-30 ft off the ground.

The inverted vee at 50ft was about the same on signal reports but the noise floor was alot higher, the flat top was a little stronger to some but not others because of its directivity and was also noisy.(y)
 
I am a fan of two pieces of wire of equal length as long as your space will allow, real old school ladder line, and a good tuner. I use a balun outside the window and into the shack with a short piece of high grade coax, and shazam: 10 through 80 meters.

Resonance is for babies. :)
 

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