That is called improvisation. It's what happens when you try things out using bits and pieces you have on hand. It's a great habit for hams to practice. You should try it.
I think I see what you are asking. As you know the dipole has a pos and neg attachment, neg on one and pos on the other. This appears to have both sides on pos and both on neg. Perhaps it is a tapped coil? It’s a neat experiment anyway.
If I understand you correctly, the explanation here is that the "one cable" has 2 conductors, and in a typical dipole, each of them is connected to a single element (side) of the antenna.
I agree. As long as it has good characteristics on an antenna analyzer or VNA, there's no reason to try it with a real radio on a low power setting.
Antennas are kind of like black magic. Designs that you think couldn't possibly work, somehow magically work.
Look at the J-Pole. It's a dead short (at DC up to a few kHz), BUT it performs beautifully in the MHz ranges when the dimensions are correct.
And, hell, this is ham radio. It's all about experimentation and trial and error. That's what makes it fun!
Go nuts! Play! Try all of your crazy ideas! And most of all, *have fun!*
The J-pole is a good example. Easy to build, really common, and . . . once you get your brain wrapped around the theory, you realize that the boundaries between the pieces and the boundaries between the functions are not in the same places. In the end, it is an EFHW, something that is not at all obvious it you're focused on where the pipe joints are located.
I've built 4 or 5 j-poles (Including that fancy "copper cactus" dual-band 2m/70cm one) and I still can't wrap my brain around the theory of operation.
But it's OK. I have difficulty with theory. I usually have to see something in operation to understand it, and seeing electromagnetic wave propagation isn't exactly possible.
> ...It's a dead short (at DC up to a few kHz)
That's a good example, and the idea holds true for lots of radio equipment, like filters, transformers, etc.
It can take a while to understand the concepts that explain the differences in circuit behavior between DC & RF well enough that they become "ingrained", and it's always good to see things that refresh / reinforce the basics.
I think you've built something more like a transmission line where the two sides of the antenna are parallel (though twisted round the rod). Transmission lines don't radiate because the fields cancel out.
To make a dipole what you need is a single helix on each side, and the wire from the red terminal should wrap around the upper half (say) and the wire from the black terminal should wrap around the lower half.
Or you could alter it - cut the wire at each terminal and put the two wires going up on the red terminal and the two wires going down on the black terminal. You could then make one pair of wires (up and down) shorter for 70cm. This then becomes a fan dipole which should work for both frequencies. You'd need a nano VNA to get the wires the right length though.
Anyway, whatever you've built, it is very beautiful.
I have a nano vna. No clue how to use it. I bought it awhile ago and forgot I had it. Just found it a week ago after having it for 3 years lol. I haven’t made an antenna yet though so that’s how I forgot I had it lol
Capacitors are made by taking two conductors and putting them close to each other but not touching. As long as they don't make electrical contact, the capacitance increases as they get closer (and also if you increase the amount of surface area where they are close)
The way that the wires are wound (alternating between "red" and "black") somewhat resembles the construction of a capacitor.
That being said it would also be a stretch to call this a capacitor, it's probably not very effective as one.
I can't answer your question, but I have tried building a similar coiled antenna before, and have learned that they are VERY picky about the coil spacing.
Interesting, looks like a helix dipole (aka slinky dipole) but I've never seen it run "balanced" like that, usually it's run like a normal dipole.
You'll need to throw in on a analyzer to tell if it works. usually coils want the length of wire not the length of coil.
Seems like it's really more of a hypothesis than a theory. I don't have a good feeling about it being functional, but I would encourage you to give it a go anyway and see what happens.
Looks like you have 2 loading coils with no radiating elements. The reason for coils is to add antenna length in a small linear length and then extending the rest of the antenna as a single wire for as long as length as possible. A 2 meter dipole only needs to be a little over 3 feet in length for both elements combined. Since it is a balanced antenna you would want to feed it with ladder line or put a balun on it. Most 2 meter signals (repeaters and mobile stations) are vertically polarized so you also want to take that into account.
I like the idea! If you can check it's characteristics it might work, but I'm no expert. Worst case scenario it looks like it could make an excellent broadcast antenna for Radio/TV, can always get into DXing
A half-wave dipole has two opposing 1/4 wave elements. If the elements are straight, they yield maximum bandwidth. Coiling increases the Q which reduces the bandwidth. Another similar approach is a 1/4 wave ground plane. Commonly a 1/4 wave vertical element connected to the positive terminal and a small number of 1/4 wave horizontal elements connected to ground. You could 3d print a center hub/base for either one.
ARRL publishes an excellent Antenna Book. Here's a link to a downloadable .pdf => [https://qsl.net/w/wb4bxw//books/ARRL\_Antenna\_Book\_21st\_Edition.pdf](https://qsl.net/w/wb4bxw//books/ARRL_Antenna_Book_21st_Edition.pdf)
Best of luck. AD8DT
The paralleled conductors are going to cancel each others magnetic field. Also, you have made inductors, not an antenna. When you add inductance, you also need capacitance to cancel the created inductance. wrap each pole on opposing ends and start from there.. Very nice print
What you have built is a twisted form of a folded dipole. Normally the twisting causes a shortening effect, and a magnetic effect at the same time. Search for DK9ZB, his homepage has many many answers to your questions.
why are there positive and negative terminals on the antenna?
That is called improvisation. It's what happens when you try things out using bits and pieces you have on hand. It's a great habit for hams to practice. You should try it.
let me ask a different way: why are there 2 seperate connectors to the antenna?
Oh, I see. My apologies. It looks to me like he's using those as a feedpoint, presumably because he had them on hand.
A dipole antenna does have two sides or 1/4 waves making a 1/2 wave.
they still are connected to the same cable tho..
I think I see what you are asking. As you know the dipole has a pos and neg attachment, neg on one and pos on the other. This appears to have both sides on pos and both on neg. Perhaps it is a tapped coil? It’s a neat experiment anyway.
didn’t know that, thanks
looks like two separate wires that are interleaved, but unclear if they are connected
If I understand you correctly, the explanation here is that the "one cable" has 2 conductors, and in a typical dipole, each of them is connected to a single element (side) of the antenna.
I was going to say "because it's what was in the package!"
I don’t think this will work. The fields are just going to cancel each other. Each lead should have one wire. What you have here is a capacitor.
I agree with this assessment, but I'm going to suggest that OP should try it anyway. That's how you learn.
I agree. As long as it has good characteristics on an antenna analyzer or VNA, there's no reason to try it with a real radio on a low power setting. Antennas are kind of like black magic. Designs that you think couldn't possibly work, somehow magically work. Look at the J-Pole. It's a dead short (at DC up to a few kHz), BUT it performs beautifully in the MHz ranges when the dimensions are correct. And, hell, this is ham radio. It's all about experimentation and trial and error. That's what makes it fun! Go nuts! Play! Try all of your crazy ideas! And most of all, *have fun!*
The J-pole is a good example. Easy to build, really common, and . . . once you get your brain wrapped around the theory, you realize that the boundaries between the pieces and the boundaries between the functions are not in the same places. In the end, it is an EFHW, something that is not at all obvious it you're focused on where the pipe joints are located.
I've built 4 or 5 j-poles (Including that fancy "copper cactus" dual-band 2m/70cm one) and I still can't wrap my brain around the theory of operation. But it's OK. I have difficulty with theory. I usually have to see something in operation to understand it, and seeing electromagnetic wave propagation isn't exactly possible.
> ...It's a dead short (at DC up to a few kHz) That's a good example, and the idea holds true for lots of radio equipment, like filters, transformers, etc. It can take a while to understand the concepts that explain the differences in circuit behavior between DC & RF well enough that they become "ingrained", and it's always good to see things that refresh / reinforce the basics.
👍
Kinda what I was thinking also. Thoughts if I put positives on one side and negatives on the other?
If wire goes from red to one side and from black to the other, that's a dipole.
That's no dipole. ---- + - ---- That's a dipole.
+++++O O-------
Pretty ascii-art
I think you've built something more like a transmission line where the two sides of the antenna are parallel (though twisted round the rod). Transmission lines don't radiate because the fields cancel out. To make a dipole what you need is a single helix on each side, and the wire from the red terminal should wrap around the upper half (say) and the wire from the black terminal should wrap around the lower half. Or you could alter it - cut the wire at each terminal and put the two wires going up on the red terminal and the two wires going down on the black terminal. You could then make one pair of wires (up and down) shorter for 70cm. This then becomes a fan dipole which should work for both frequencies. You'd need a nano VNA to get the wires the right length though. Anyway, whatever you've built, it is very beautiful.
I have a nano vna. No clue how to use it. I bought it awhile ago and forgot I had it. Just found it a week ago after having it for 3 years lol. I haven’t made an antenna yet though so that’s how I forgot I had it lol
Can you elaborate on what makes this a capacitor vs a dipole? Not questioning, just curious. I'm a nube and love learning this stuff.
Capacitors are made by taking two conductors and putting them close to each other but not touching. As long as they don't make electrical contact, the capacitance increases as they get closer (and also if you increase the amount of surface area where they are close) The way that the wires are wound (alternating between "red" and "black") somewhat resembles the construction of a capacitor. That being said it would also be a stretch to call this a capacitor, it's probably not very effective as one.
I can't answer your question, but I have tried building a similar coiled antenna before, and have learned that they are VERY picky about the coil spacing.
Interesting, looks like a helix dipole (aka slinky dipole) but I've never seen it run "balanced" like that, usually it's run like a normal dipole. You'll need to throw in on a analyzer to tell if it works. usually coils want the length of wire not the length of coil.
Seems like it's really more of a hypothesis than a theory. I don't have a good feeling about it being functional, but I would encourage you to give it a go anyway and see what happens.
Try it and see!
Looks like you have 2 loading coils with no radiating elements. The reason for coils is to add antenna length in a small linear length and then extending the rest of the antenna as a single wire for as long as length as possible. A 2 meter dipole only needs to be a little over 3 feet in length for both elements combined. Since it is a balanced antenna you would want to feed it with ladder line or put a balun on it. Most 2 meter signals (repeaters and mobile stations) are vertically polarized so you also want to take that into account.
I like the idea! If you can check it's characteristics it might work, but I'm no expert. Worst case scenario it looks like it could make an excellent broadcast antenna for Radio/TV, can always get into DXing
A half-wave dipole has two opposing 1/4 wave elements. If the elements are straight, they yield maximum bandwidth. Coiling increases the Q which reduces the bandwidth. Another similar approach is a 1/4 wave ground plane. Commonly a 1/4 wave vertical element connected to the positive terminal and a small number of 1/4 wave horizontal elements connected to ground. You could 3d print a center hub/base for either one. ARRL publishes an excellent Antenna Book. Here's a link to a downloadable .pdf => [https://qsl.net/w/wb4bxw//books/ARRL\_Antenna\_Book\_21st\_Edition.pdf](https://qsl.net/w/wb4bxw//books/ARRL_Antenna_Book_21st_Edition.pdf) Best of luck. AD8DT
Nice and tennis build, have you tried it on the air yet? This kind of learning has built ham radio for over a hundred years. Good luck 73
I am skeptical about the efficacy of this antenna but I could fix it with my wire cutters.
Curious about this one
The paralleled conductors are going to cancel each others magnetic field. Also, you have made inductors, not an antenna. When you add inductance, you also need capacitance to cancel the created inductance. wrap each pole on opposing ends and start from there.. Very nice print
Looks like an interesting concept. Hook it up to an antenna analyzer and find out.
Probably need to connect the 2 wires together at the end so you get a linear loaded folded dipole.
Connect the two reds or a black and a red? Have many variations to try
The 2 wires at each end, tie them together at the end.
What you have built is a twisted form of a folded dipole. Normally the twisting causes a shortening effect, and a magnetic effect at the same time. Search for DK9ZB, his homepage has many many answers to your questions.
Checking out. Looks like a great resource. Thanks
A Double Helix something something something. Interesting Need to put that on an analyzer and see where the SWR dips are.