Dipole?

[kn4bbc]

I'm considering putting up a 80/40/20 dipole soon and I'd like to ask for some advice. There is a TON of info out there and I'm a bit confused.

I am concerned about the length of feed line that I would need to pull this off (see measurements in the attached images). Here are some details;

Shack is located on the second floor, close to where I show the feed line coming in to the house
- I need~30 feet of internal feed line
- It's ~150 feet to the treeline at the point marked on first image
- Trees are ~100 feet tall and I have the means to get lines nearly to the top.
- Presently running a Kenwood 450sat at 100w (internal autotunner)
- I have an MFJ manual tuner
- Placement in the first image would need ~180 feet feed line (150 outside 30 inside)
- Placement in the second image would need ~245 feet of feed line (215 outside 30 inside)
- I'd run rope from an eye hole bolt on the house to the trees and support the feed line with the rope
- Presently using a 9:1 unun (balun designs) and 124.5 foot #26 wire
-

The questions;
- What feed line. Talking to the locals here I'm getting massively different opinions
- Is it worth it? or should I stick with the random wire?
- if yes... fan or trap?

1527215273

[KC2UGV]

For internal feedline, LMR400 (Due to distance), outside feed line, I'd do ladder line. As for antenna, you can't beat a dipole, except with a yagi.

If you're brave, you can try ladder line all the way. Might get interesting in the house itself. If you have a large budget, LMR400 is about as lowest loss as one can get.

Another suggestion: run the dipole from the tree line, to the corner of the house. You'll save on feedline distance.

[kn4bbc]

You would use LMR400 for the 30 foot feed line then switch to ladder for the outside run? How would you switch from LMR400 to ladder?


For internal feedline, LMR400 (Due to distance), outside feed line, I'd do ladder line. As for antenna, you can't beat a dipole, except with a yagi.

If you're brave, you can try ladder line all the way. Might get interesting in the house itself. If you have a large budget, LMR400 is about as lowest loss as one can get.

Another suggestion: run the dipole from the tree line, to the corner of the house. You'll save on feedline distance.

[W5BRM]

You would use LMR400 for the 30 foot feed line then switch to ladder for the outside run? How would you switch from LMR400 to ladder?

http://www.americanradiosupply.com/coaxial-cable-to-ladder-line-transition-converter/

Something like this. Can be home made as well. Hang it outside where your lmr400 or whatever coax leaves the building. Search out dipole antenna balun. That will be a good starting point.

[PA5COR]

80 meter 1/2 wave dipole will work on 40/20 as well, ad 10.
Internal tuers will only do 1:3 SWR, nothing higher, so the external tuner will do a much larger SWR.
If the tuner has open line connection, go for open line ( ladder line) we mostly make it ourselves here .
The only little problem is feeding it n the house, after that just keep it away from metal and electricity lines, and just use it.
Getting the open line in the house, use window that opens and make fitting piece of wood with 2 copper or messing tapped studs through it, use wingnuts to disconnect quickly in case of thunderstorms.

Did that for several friends, works like a charm.
You can make a fan dipole, which is difficult to trim, or just use the above solution which will work as well
In case of the fan dipole and once trimmed for each band swr doesn't make a big problem and the internal tuner should handle it without a problem.
Negative- more wire, more weight to keep up and in trees better look out for giving it some space to work in wind.
100 feet is quite high, keep it a bit lower, there the trees move less.
Ideally a 1/2 wave above ground is for most of us not easy to do, but 1/4 wave above ground of the lowest working frequency works fine.

That is 60 feet for 80 meters.
Nice for 40 and for 20 perfect.

[KC2UGV]

80 meter 1/2 wave dipole will work on 40/20 as well, ad 10.
Internal tuers will only do 1:3 SWR, nothing higher, so the external tuner will do a much larger SWR.
If the tuner has open line connection, go for open line ( ladder line) we mostly make it ourselves here .
The only little problem is feeding it n the house, after that just keep it away from metal and electricity lines, and just use it.
Getting the open line in the house, use window that opens and make fitting piece of wood with 2 copper or messing tapped studs through it, use wingnuts to disconnect quickly in case of thunderstorms.

Did that for several friends, works like a charm.
You can make a fan dipole, which is difficult to trim, or just use the above solution which will work as well
In case of the fan dipole and once trimmed for each band swr doesn't make a big problem and the internal tuner should handle it without a problem.
Negative- more wire, more weight to keep up and in trees better look out for giving it some space to work in wind.
100 feet is quite high, keep it a bit lower, there the trees move less.
Ideally a 1/2 wave above ground is for most of us not easy to do, but 1/4 wave above ground of the lowest working frequency works fine.

That is 60 feet for 80 meters.
Nice for 40 and for 20 perfect.

FWIW, this is what I did, however, not for 80M (Not enough wire in the air yet). 300 Ohm twinlead right to the tuner in my shack.

[KG4NEL]

How would you switch from LMR400 to ladder?

1:1 current balun. Either external, or a tuna that has one built in. If external, keep the tuner-to-balun runs relatively short, as even low-loss coax doesn't like high SWRs all that much (it's not like the SWR on the ladder line part is any lower, but open wire/twinlead exhibits much, much lower losses under high SWR conditions than coax does)

[KD8TUT]

For internal feedline, LMR400 (Due to distance), outside feed line, I'd do ladder line. As for antenna, you can't beat a dipole, except with a yagi.

If you're brave, you can try ladder line all the way. Might get interesting in the house itself. If you have a large budget, LMR400 is about as lowest loss as one can get.

Another suggestion: run the dipole from the tree line, to the corner of the house. You'll save on feedline distance.

I agree...

I've got about 150ft per run out to my antennas. All LMR400 flex. Works great.

[WZ7U]

I like the response to a basic question here much more than over at that other antenna site.... thank you for that.

[PA5COR]

Something to ponder about.
Traps intrduce some small losses, and make the bandwith after the trap smaller.
Dipoles have less noise throught heir balanced system as end fed antenna's, which also need an balun to get from the high impedance to the lower impedance.

For low bands using a good quality coax like LMr 400 will intoduce negible losses even in what longer runs.
Open line has the least losses, i prefer to get all the power made from the transceiver to get to my antenna and the antenna to raadiate it as effective as possible, which means reception will also be optimal, as far your house/land neighbors and possibilities to create hang up points allow you to do.

The antenna system is the most important part of the whole station, not your radio not your amplifier or microphone ;)
The most effective money spend on your station is the antenna system.
There are no stupid questions on antenna systems, i'm a ham for 40 years, have stacks of antenna books and build a gazillion antenna's and i'm still learning.

My simpleton observations, the more wire as high up in the air you can get, the better the results.
Don't be affraid to experiment, even going outside the beaten paths of standard antenna rules.
Your situation is always unique, experimenting on where to put up your antenna, and which one will determine how well your station will work.

After throwing in open windows, did you consider a square loop for 80 and up? if you have the spot and enough real estate for it, it is a very good antenna, has gain over the dipole and is quieter through it's closed system, build a few myself 160 and up.
Mine were fed with open line and the last bit a 1:4 balun and short coax to transceiver.
Build for 80 it will work fine up to 10 meters.