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Posted: 5/14/2022 8:22:48 PM EDT
Does anybody know if anything exists that would look like a PL259 Tee Fitting, but would be internally wired so that the 2 antennas attached to it would function as a dipole?
I am making a backpack antenna and I want to connect 2 mobile antennas together to make dipole. Thanks ETA, Basically somthing that looks like this: Amazon but is internally wired like this:  Using 2 of these antennas to make a dipole: Comet SBB-1 Comet Antenna I like the above antenna because it is the perfect length for what I need, rubber coated (good to have for a backpack radio) and rated for the full power of my radio. |
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Posted: 5/14/2022 8:32:51 PM EDT
[#1]
@benb
What band(s) are you interested in using: looking for element lengths here. I use 75 Amp power poles to connect/ disconnect my feed line (ladder line) because they have a large amount of surface area and fit tightly. Smaller ones would fit if you could keep them from disconnecting due to the weight of the wire. 73, Rob On your edit, Are you simply using the 2m/ 70cm bands? |
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Posted: 5/14/2022 8:33:04 PM EDT
[#2]
there's a few things like that with 3/8" stud thread mounts to make a dipole out of two hamsticks or collapsing whips, but I can't say I've seen one with SO239's for the elements. You could pretty easily make something with a bit of plastic and 3 surface mount SO239s.
I'm curious, what mobile antennas were you planning to use? |
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Posted: 5/14/2022 8:34:17 PM EDT
[#3]
Quote HistoryQuoted: @benb What band(s) are you interested in using: looking for element lengths here. I use 75 Amp power poles to connect/ disconnect my feed line (ladder line) because they have a large amount of surface area and fit tightly. Smaller ones would fit if you could keep them from disconnecting due to the weight of the wire. 73, Rob Quote HistoryQuoted: @benb What band(s) are you interested in using: looking for element lengths here. I use 75 Amp power poles to connect/ disconnect my feed line (ladder line) because they have a large amount of surface area and fit tightly. Smaller ones would fit if you could keep them from disconnecting due to the weight of the wire. 73, Rob My frequencies are all UHF Quoted: there's a few things like that with 3/8" stud thread mounts to make a dipole out of two hamsticks or collapsing whips, but I can't say I've seen one with SO239's for the elements. You could pretty easily make something with a bit of plastic and 3 surface mount SO239s. I'm curious, what mobile antennas were you planning to use? I might be confusing PL259 and SO239. Do you have a link to the piece for connecting hamsticks? That might work. Maybe I can adapt it too. Also, just edited the OP with the antenna I am using. I tried to use it just connected to the end of the feed line. It had pretty bad performance lol. |
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Posted: 5/14/2022 8:37:48 PM EDT
[#4]
@benb
Seriously, look for a beam antenna that takes down and a small collapsible mast that doubles as a walking staff. You'll make many more contacts. 73, Rob |
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Posted: 5/14/2022 8:38:04 PM EDT
[#5]
Quote HistoryQuoted: My frequencies are all UHF |
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Posted: 5/14/2022 8:45:16 PM EDT
[#6]
Quote HistoryQuoted: @benb Seriously, look for a beam antenna that takes down and a small collapsible mast that doubles as a walking staff. You'll make many more contacts. 73, Rob I got other antennas in the pack, but this if for on the go in the pack. I got a folding arrow antenna that works pretty good and a roll up antenna that I can hang in a tree. |
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Posted: 5/14/2022 8:47:10 PM EDT
[#7]
Quote HistoryQuoted: For something that small and for something you plan to backpack with, why not just make it from scratch with something as simple as any old wire secured among a length of dowel rod or similar to hold it rigid? Or use one of those mobile antennas and make a ground plane mount for it, etc. I might do that, but I figured I would ask here first if somthing already exists. I don't really want the half sticking out of the pack to be ridged. The flexibility of that Comet antenna is one thing I like about it. Making a ground plane wouldn't be a good option for the backpack IMO. Seems like a dipole would be much more practical. |
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Posted: 5/14/2022 9:07:54 PM EDT
[#8]
Quote HistoryQuoted: I might do that, but I figured I would ask here first if somthing already exists. I don't really want the half sticking out of the pack to be ridged. The flexibility of that Comet antenna is one thing I like about it. Making a ground plane wouldn't be a good option for the backpack IMO. Seems like a dipole would be much more practical. One option, fashion a mount for one of your comet antenna to attach to your pack, ideally so it sticks up near the top. Then attach to the metal of the mount (which should be the ground side) a tuned length of wire that hangs down, some would call it a counterpoise but it's basically acting as the other side of the dipole. Some guys here have done this when they remote mount an HT antenna onto the back of a plate carrier or vest. ETA: here's a pic I found on the web, something like this but it looks like they used an HT antenna and a bit of PVC pipe as a short mast. But you can see the hanging wire as the counterpoise/other side of a dipole.  |
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Posted: 5/14/2022 9:47:48 PM EDT
[#9]
Bulkhead SO-239
They also make center units for dipoles. Just add wire. Hamsticks are 3/8" 24 thread. Thete's a dipole adapter that holds 2. On 2m, if you want omnidirectional, a jpole can be easy and portable. For 2m directional, a 2m moxon might be a winner for directionally and portability. |
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Posted: 5/14/2022 9:56:53 PM EDT
[#10]
Roll up dipoles are pretty easy to build if you want one for FM. Made good contacts on POTA on band openings too. I think I saved the plans too.
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Posted: 5/14/2022 10:39:29 PM EDT
[#11]
Quote HistoryQuoted: So this is for on the go? Remember, for FM VHF/UHF stuff you want vertical polarization so your dipole would have to be oriented vertically. One option, fashion a mount for one of your comet antenna to attach to your pack, ideally so it sticks up near the top. Then attach to the metal of the mount (which should be the ground side) a tuned length of wire that hangs down, some would call it a counterpoise but it's basically acting as the other side of the dipole. Some guys here have done this when they remote mount an HT antenna onto the back of a plate carrier or vest. ETA: here's a pic I found on the web, something like this but it looks like they used an HT antenna and a bit of PVC pipe as a short mast. But you can see the hanging wire as the counterpoise/other side of a dipole. https://w4va.org/wp-content/uploads/2019/06/pic1_ed.jpg Thats actually the same backpack I am using for this lol. I'll look more into this. I've never seen this type of setup. |
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Posted: 5/14/2022 10:44:30 PM EDT
[#12]
Quote HistoryQuoted: Roll up dipoles are pretty easy to build if you want one for FM. Made good contacts on POTA on band openings too. I think I saved the plans too. Thanks, yep I know there are other antenna options. I have a roll up antenna that works good for putting in a tree. I think the whip is a better option for on the go. So nobody knows of a product that makes a dipole out of 2 mobile antennas (like the hamstick thing, but for PL259/SO239)? I know they make ground plane independent antennas (I had to use one on my jeep since it doesn't have a usable ground plane). I might end up using one of those. I was just hoping to use my rubber coated flexible whip for this application. |
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Posted: 5/14/2022 10:48:15 PM EDT
[#13]
Think maybe you could fab one out of some chassis mounts?
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Posted: 5/14/2022 11:01:05 PM EDT
[#14]
Quote HistoryQuoted: Thanks, yep I know there are other antenna options. I have a roll up antenna that works good for putting in a tree. I think the whip is a better option for on the go. So nobody knows of a product that makes a dipole out of 2 mobile antennas (like the hamstick thing, but for PL259/SO239)? I know they make ground plane independent antennas (I had to use one on my jeep since it doesn't have a usable ground plane). I might end up using one of those. I was just hoping to use my rubber coated flexible whip for this application. None that I am aware of. Hamstick dipoles are normally for HF, and use 3/8-24 threads. Are you using UHF only, or are you using VHF as well? If Uhf only, your antenna can be much smaller. Walking around the woods with a horizontal dipole would be a pain in the ass. What you are proposing even vertical would suck. |
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Posted: 5/14/2022 11:05:13 PM EDT
[#15]
Quote HistoryQuoted: None that I am aware of. Hamstick dipoles are normally for HF, and use 3/8-24 threads. Are you using UHF only, or are you using VHF as well? If Uhf only, your antenna can be much smaller. Walking around the woods with a horizontal dipole would be a pain in the ass. What you are proposing even vertical would suck. It will be vertical. It shouldn't suck. The mobile antenna I linked above is 16" long. The pack is about 20" tall so one half the dipole would stick out about 12" and is a flexible whip. UHF only. Sounds like this does not exist. I'll think of something else. |
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Posted: 5/15/2022 1:23:28 AM EDT
[#16]
This looks pretty interesting.
 UHF/PMR446 Bazooka Antenna Homebrew |
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Posted: 5/15/2022 8:01:02 AM EDT
[#17]
https://www.talleycom.com/viewProduct?rlProdNum=R/FRFU534
 Attached FileYou can get those in a variety of genders. Commonly referred to an an "injection tee" and is used for making measurements. I wouldn't do this however. You need vertical polarization which is going to be awkward, be easier to use a UHF bulkhead and add a couple of radials. Or get a half wave mobile which doesn't need much of a ground plane. If you must have a vertical dipole I'd make a sleeve dipole by stripping some coax and folding the braid back over the sheath. The gain you'll add with all this is minimal from a practical sense. Much better either stop and put a roll up in a tree (higher is more important that gain in my experience) or use a yagi/moxon. |
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Posted: 5/15/2022 8:43:36 AM EDT
[#18]
https://www.gigaparts.com/so-239-triple-t-adaptor-teflon.html?msclkid=d34ee6644814167469a184e4bd360865&utm_source=bing&utm_medium=cpc&utm_campaign=*Shopping%20-%20JF&utm_term=4582145989392063&utm_content=MFJ
they’re out there. |
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Posted: 5/15/2022 9:03:15 AM EDT
[#19]
realistically, at VHF / UHF frequencies height is everything, so wearing a backpack with a 16 inch antenna out the top ( with a ground plane or counterpoise ) or just holding a handheld radio with the antenna attached is going to yield pretty much the same results. If you added a full /14 wave antenna with a ground plane / counterpoise it would work a bit better than the hand held.
if you can't do a ground plane, just adding a 1/4 wavelength counterpoise would be almost the same improvement. If you take the antenna away from the handheld and mount it someplace, you lose the ground plane / counterpoise because when you are holding the radio, your hand and arm and some of the rest of your body IS the ground plane / counterpoise so when the antenna is not being held you need to replace the counterpoise or the performance is going to suck and the SWR will be very high. |
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Posted: 5/15/2022 11:31:41 AM EDT
[#20]
Quote HistoryThat does look interesting for a pack and go type of antenna. |
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Posted: 5/15/2022 11:45:02 AM EDT
[#21]
Quote HistorySometimes called the "flower pot" antenna, because they could be tied to a planting stake and hidden in a potted plant on a balcony or similar for HOA concerns. The standard version is essentially a vertical half wave dipole. This site has nice plans for making them, as well as some variations that might give some more gain. https://vk2zoi.com/articles/half-wave-flower-pot/ |
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Posted: 5/15/2022 3:28:33 PM EDT
[#22]
Budwig connector?
https://budwigmoldedproducts.com/antenna-connector-and-insulators/ |
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