Could something like this be done with CB?

[BobCB]

I keep seeing videos like this on youtube where Hams use some way to launch an antenna up a large tree. Some use weights, slingshots, or I've even seen one that used an air-power launcher.
[youtube][/youtube]

What I'm wondering is if something like this could be done with CB. Of course it wouldn't be of much use for an emergency or anything like that but with the height of some of these trees in my area it would be cool to try simply because of the height you could achieve without putting much effort in. If you had good enough aim or a good arm you could get some sort of wire antenna 75ft. into a tree, as some of the ones near my base are that tall. So, could I do something like this for CB? If so, how would you go about creating the antenna itself?

[Slim Pickins]

I had a sloped dipole tied to a tree top and the ground. Worked pretty good. The sloped dipole lets you get the coax off at 90 degrees to the antenna which dipoles seem to like. All kinds of posts on here about building dipoles. Hook it to a handheld and it might work pretty good.

73s
Paul

[BobCB]

I am familiar with dipole antennas, I was just wondering if it was possible to create an end-fed antenna like the video rather than center-fed like a dipole. If I could make an end-fed antenna for CB it would be much easier to get it setup, instead of trying to do it so that the feed line is at a 90 degree angle. Would that be possible?

I'll keep searching.

[Night Crawler]

If I could make an end-fed antenna for CB it would be much easier to get it setup, instead of trying to do it so that the feed line is at a 90 degree angle. Would that be possible?

An end-fed random wire could be used for 11 meters but it would need a tuner and a good ground system.

[BobCB]

So a dipole won't need a tuner? Why the difference? I could just as easily try a dipole, just thought it would be easier if it were end-fed, but I don't have a tuner and probably can't afford one anyhow.

['Doc]

I don't see any reason you couldn't use one of those 'launching' methods for any antenna, end fed, center fed, whatever. There are a couple of ways to do the "feed line comes out the bottom leg" of a center fed dipole antenna. One simple way is to skin the outer insulator off of a length of coax for just a little over 8 and 1/2 feet, call it 9 feet to have some 'extra' length to play with. Then, skin the braid back over it's self and over the outer insulation of that length of coax. The center conductor is the top half, the braid is the bottom half of that dipole. Trim each leg as you would any dipole to tune it. There's a 'catch' though. There are some high voltages on the ends of any dipole, but since the feed line is coming out of the 'end' of one leg of that dipole, you need to put a choke a little ways down the feed line from where it exits the braid. That'd keep some/most of that extra voltage off of the feed line where is does 'not good' things.
Want that thing tuned for 11 meters? Make it the right length. For 10 meters? Same thing, just change the length. How about 80 meters? Better find one really tall tree first!
- 'Doc

[goofy]

Random wires generally need a tuner, but yah, they would work on 27mhz.

A Zepp antenna would probably work too, but again you need a tuner...

[BobCB]

I don't see any reason you couldn't use one of those 'launching' methods for any antenna, end fed, center fed, whatever. There are a couple of ways to do the "feed line comes out the bottom leg" of a center fed dipole antenna. One simple way is to skin the outer insulator off of a length of coax for just a little over 8 and 1/2 feet, call it 9 feet to have some 'extra' length to play with. Then, skin the braid back over it's self and over the outer insulation of that length of coax. The center conductor is the top half, the braid is the bottom half of that dipole. Trim each leg as you would any dipole to tune it. There's a 'catch' though. There are some high voltages on the ends of any dipole, but since the feed line is coming out of the 'end' of one leg of that dipole, you need to put a choke a little ways down the feed line from where it exits the braid. That'd keep some/most of that extra voltage off of the feed line where is does 'not good' things.
Want that thing tuned for 11 meters? Make it the right length. For 10 meters? Same thing, just change the length. How about 80 meters? Better find one really tall tree first!
- 'Doc

I actually know how to build one of the antennas you described. I am using one as a scanner antenna for VHF/UHF, cut to those frequencies of course. Would this work on the CB band without a tuner? Guess now I'll be on the lookout for a REALLY long piece of coax.

['Doc]

Why wouldn't it work on 'CB' if it'll work somewhere else? Would you have to have a tuner? Not if you do the tuning correctly. But then, tuners are nice to have around!
- 'Doc

[HomerBB]

The end fed sleeved dipole as Doc described it does not need a tuner. It is actually fed in the center as that is where the two halves of the dipole split apart in the opposite direction from each other, however the coax exits one end making it easier to mount the dipole vertically. For the antenna itself, all the coax you need is around 18 feet length. Add enough coax to that to make 5 to 6 wraps around a 4 inch diameter piece of PVC for a choke and your ready to go. I've done it. Its works well for 27mHz.

[BobCB]

Sorry for all the questions, but how would this antenna, pulled up high into a tree, perform against an Antron A99? My antron is mounted to a pipe about 12ft in the air, and I live on a mountain. Would I even see a change if I made an antenna like this and hoisted it up a tree somehow? This definitely wouldn't be a replacement for the A99, but before I start building the antenna it would be nice to get a baseline estimate on performance between the two.

[443 Arizona]

hey big doghang up a full wave on the horizontal plane at tree top height, put your antenna lengths between insulators, hang the whole works in the middle of the span, using ski rope to hold it between the trees.
look in the arrl book, (library)
if you build it, it will resonate, should be a good skip setup.

or , get a helium balloon big enough to get you ,,, hmmmm 500ft ?
understanding the principles will let you build anything . good luck

['Doc]

How would that 'sleeve' dipole compare to an 'A99' for instance? Well, they are both 1/2 wave antennas, so, their performance would be -roughly- the same. I would expect some differences (either way), which would be normal for any two antennas and different mounting locations. Huge differences? I very much doubt it. Worth trying it to see? I think so. Worth substituting one for the other? Eh, who knows till you try it and see? And then all of it depends on how well each antenna is tuned, right?
All in all, you are talking about maybe 25 feet of coax (guestimate) and a PL-259 maybe. Throw in a 100 yard spool of 'trot-line' cord. What's that, maybe $20? So... ?
- 'Doc

[drdx]

An antron is just a really expensive wire antenna, just in a fancy case. For something quick and simple, and it is in the arrl book too I think, how about a simple 1/4 wave vertical (vertical to center of coax) with 2 or more wire radials. They bottom feed well and only need one high hanging point. Visualize it as a wire starduster or maybe penetrator, depending on the flatness or slope the radials end up being set up.

-drdx

[BobCB]

Thanks for the help everyone. At the very least I have something to think about, it's always fun building an antenna. Maybe now I can put a use to these 75ft tall pine trees that are around here, hehe.

[BobCB]

On second thought . Would something like this work instead? [Please login or register to view this link]. Will this antenna require an antenna tuner, or anything else like that? I'm a bit confused where it says tie both ends together, what does that mean?

And for the 1/4 wave antenna, would these instructions get me going [Please login or register to view this link]?

[HomerBB]

If the idea is to simply get higher, tie your A99 off to a rope from the very top and pull it up into the top of the tree.

[BobCB]

No, that's not the idea. I'm wanting to make my own antenna as a project and while I'm at it see if I can pull it up a tree using a method like the video I posted.

[Night Crawler]

Would something like this work instead? [Please login or register to view this link]. I'm a bit confused where it says tie both ends together, what does that mean?

Beats me that's the part that doesn't make any sense unless he means putting it up in a Y configuration but that's not a loop as stated in step 5.
I'd like to meet the guy that wrote that article and see his working model of that antenna.

And for the 1/4 wave antenna, would these instructions get me going [Please login or register to view this link]?

Make the top one the 1/4 wave ground plane you can use wire for all the elements radiator and ground radials it shows four for the ground radials but two will work ok. In the article it says to make the radiator 102 inches but make it 104 inches along with the ground radials that's the one drdx was explaining how to make.

[BobCB]

How would I attach the radials? If the whole thing is wire and coax, how do I attach the radials and more so, how do I make them stay at a 45 degree angle? This is the main part that confuses me. Do I need a steel tube like the directions say or can the stripped coax support itself? Everyone has to bear with me, I'm a step-by-step kind of guy when it comes to building antennas.

I feel like I just jumped into the deep end of the pool.

['Doc]

That first 'example' is basically a 1/2 wave dipole folded around to make a loop. The two 'ends' of that dipole are not connected electrically, but separated by an insulator. There are a couple of things that are sort of 'iffy' in my opinion. The first is using 'TV' coax, which is typically 75 ohms. It's just not the 'best' idea in the world. That 'loopy' dipole does work, but also has complications for impedance matching (SWR). If you want to play with it, have at it!

The second 'example' is a fairly common method of making a 1/4 wave groundplane antenna, and the 'ring' type impedance matching device is also fairly common. It's a sort of 'bent' gamma match, kind'a. It also works (ask Booty Monster).


You'll have lots of company in the 'deep end', everybody's been there at least once!
How do you keep things at the selected angle? More rope and stretched to the right tie-off point. If you can get any coax to 'stand up' by it's self you'll be doing better than anyone else I know! (One reason why I recommended a 100 yard spool of that 'trot-line' cord, you'll need lots of stuff to tie things off, you know??)

I think you'll find that the 'angle of the dangle', the angle those radials slope at, is going to be sort of variable and dependent on how you can get the thing strung up (or, use metal tubing and a firm mount to keep things 'right'). That 'angle can also be used to do some impedance matching. The more they 'slope', the higher the input impedance is, and that means that the SWR can be made lower. A typical 1/4 wave antenna has an input impedance close to 25 ohms, not 50 ohms. So raising that input impedance is 'good'. You do that by varying the 'angle of the dangle' of the radials. The same thing holds true for any 'groundplane' type antenna.

Another thing to remember is that you are dealing with wire, which is cheap compared to tubing or whatever. You can add to wire antennas by soldering, which isn't always true for other types of conductors. So, a couple hundred feet of wire will go a very long ways with antennas, even counting mistakes. The only really hard part is making the @#$ wire stand up straight! Starch doesn't work. Tall trees do work to hang things from. Fiberglass poles do too, doesn't matter if the wire is on the inside or the outside since fiberglass is 'invisible' to RF. Dry wood is an insulator, wet wood isn't (sap in trees makes them sort of conductive, but not a huge amount, it's seasonal too).
Have fun.
- 'Doc

[goofy]

My take-it-for-what-its-worth advice, is not to even bother with a 1/4 wave wire groundplane. It's much easier just to build a dipole, and it will work better.

A 5/8 wave ground plane will do a little bit better than a dipole, but not that much.

A dipole also lends itself to horizontal polarization, which is generally better for DXing (but not as good for local chatting)

[Night Crawler]

How would I attach the radials? If the whole thing is wire and coax, how do I attach the radials and more so, how do I make them stay at a 45 degree angle?

Like this it's showing the length for 2 meters but for 11 meters make the elements 104 inches.
[Please login or register to view this link]

You could also use an insulator between the radiator and ground radials and separate the shield from the inner conductor with the inner connductor going to the radiator and the shield going to the ground radials.
To make the ground radials stay at a 45% angle tie fishing line to the ends and anchor them near the bottom of the tree or whatever support your using.

If you want to experiment with wire antennas what you really should do is get a tuner and feed the antenna with an open wire feeder makes things a lot easier.

[Sporty Mike]

Very interesting thread Bob, alot of good links in there.


Mike

[BobCB]

To be honest, I've never even looked that hard at antenna tuners so I don't know if they would be out of my price range or what I should look for.

Thanks for the link Night Crawler, the SO239 idea that the link shows is just what I was looking for, quick and easy.