I built this antenna and tuned it to 1.05:1 SWR @ 463 MHz, using a NanoVNA. It was cheap and dead simple. I put it up 25 feet on a hill in the woods in North Georgia connected to a BTECH 50x2. I set the frequency to 462.725 MHz, set my phone next to the radio and started audio recording. I drove all over and into two towns; about a 10 mile radius in multiple directions, test transmitting everywhere from a 5W HT. This antenna picked up EVERY transmission! 10 miles simplex with 5W is NOT BAD AT ALL!
I built this antenna and have been using an HT. I'm upgrading to the btech 50v2 this week I wasn't sure if the antenna would be able to handle it or not so glad to see you are using it fine. Any updates since you originally posted
The wobbly end of the tape is to accommodate for whether you’re pushing or pulling on the hook. The wobbliness is exactly the thickness of the hook so it’s always accurate. Thanks for the video!
No shame intended, since it was only this year that I learned why “the end of these things is always sloppy”. The tape measure is designed to move the end out when measuring outside diameter and in when measuring inside diameter. This accommodates the thickness of the tab on the end of the tape. This is a feature, not a defect.
Beautifully and clearly presented step-by-step antenna project. Thanks for taking the time to put this together! [EDIT: A couple of hours after watching your video I raided my junkbox and built the GMRS J-Pole to your specs. It took me twice as long as you but it came out great with my CAA-500 Mark II showing 1.1:1 resonance at 464.5 MHz and 1.4:1 at the 467.7250 and 462.5625 GMRS band edges. I'll hang it off the side of the tower tomorrow weather permitting. Thanks again!]
A tip I learned is before you start, clamp one end of your wire in a vise, then use your drill to twist it. This straightens the wire and makes it quite rigid.
A branded steel tape should give accurate measure. The sliding hook is to account for the thickness of the hook when taking measurements in tension or compression.
What a valuable video! Thank You! That was a good stopping point. For a base antenna that probably won't have too much difficulty hitting a local repeater, which receives on 467.625Mhz center frequency, but simplex 462.625Mhz between small 5W radios might be where you'll NEED your best performance.
I have an Ed Fong GMRS J-pole. It's a phenomenal antenna and I always get excellent reports on my local repeater. I tested it with my Nano VNA and It is getting 1.22 in the simplex range, and 1.28 in the repeater range.
Thank you for your excellent video. However, I have measured carefully and built this antenna 4x now and cannot get good SWR (3+:1). I am using 13' of RG-58 and a HT radio. My thought was I could hoist it up a tree at camp. Any thoughts as to why this isn't working for me? I get longer measurements when I use online calculators.... using VF = .96. Thanks in advance for your consideration! PS--Menards carries the 200 psi PVC...... Home Depot did not.
Nice video. You can also adjust your SWR by moving your feed point connection up or down. Requires playing with soldering and unsoldering. Nice simple project.
I have a Question -- once the Antenna is completed and the Cable is plugged into the SO-259 on the Antenna, will doing a test on the opposite end of the Cable with a Continuity Test show a Short??
I commend this video because it will help anybody build an antenna for whatever service they are into. If you have the parts to build an antenna already, all you would have to source is the wire. I suggest using #10 AWG to lower the antenna "Q" and make it more broadbanded than it would be with #14 AWG. the project might take two hours to complete, including the time to mount it wherever you choose. I would mount it on a metal roof, or on a metal pole above the adjacent tree line for unobstructed access to a repeater. Good luck!
Any conductive material will work, even stainless (whips have been made of stainless for years). Uninsulated wire will require less velocity factor, therefore will need to be slightly longer. Any material other than copper won't have the advantage of solder connections.
Nice J pole for any frequency ! Just use the formula for a j pole and then trim for resonance. I would seal the PVC and use it as a radome to keep moisture out so it would not change the resonance any. Better to build an antenna and learn from it, than just buy it off the shelf and learn nothing. Well Done ! 73 de W4FJF.
If your antenna has a vswr of 1.2 after the first build just leave it like that. Is is excellent. It amounts to a reflection of only 0.8 %. Even 10 meter coax or a connector will cost you more power.
Use 1/4 or 3/16 inch copper tube, it will stand up better and all you have to do is spray a sealant on it to prevent corrosion, just like you would with 14 Ga wire, except, you do not need a supporting structure. Also, using the pipe will make the antenna more broad-banded for repeater use.
Copper pipe isn't as easy to snip or solder. You only need 5Mhz of bandwidth. 1.5:1 for repeater inputs and 1.1:1 for simplex is tough to beat... not sure it's worth the added difficulty trying to build and tune pipe.
@Gruuvin1 I mucked around with 8 and 10mm microbore copper heating pipe, originally just to connect to patch antennas I'd made, but after a bit of experimentation I was building yagis out of it and a few other things, and it's great stuff. I found various ways of cutting it, but the little screw down cutters that plumbing shops give away for free or next to nothing are the best 👌 the blade leaves a beveled edge, which seems to be more forgiving than the sharp edges that another cutter got me, and a hacksaw was useless, nearly always bend the length doing that And I use a spray ignition sealant for old ass cars that's actually a thin layer of wax unlike wd40 or others, that helps on anything really, stops condensation on pipes indoors too! 😂
i have a couple questions 1- if you used sch-40 pipe would it hurt your rx and would if effect tuneing ? 2- ccan you use a larger wire say 10awg insulated or bare what would that effect ? Ok that's three questions sorry thank you wrug770
Hello sir, thanks for the video. I’m new to GMRS radio so I ask forgiveness ahead of time for my question 😅 I noticed you soldered the center wire of the coax to one part of the house wire and then soldered the shielding to another part of the same wire. Why doesn’t that cause a problem? Seems like it would be bad to have antenna directly connected to ground. Or were they separated electrically and I missed it?
Thats funny,my brother and I are newbies also and i was going to use a cb antenna base and saw the threaded stub was just a frickin solid stub!!! I thought how does that magic work all connected to one stud!!!
You mention 14GA as your selected cable. What is the variation (if any) if using 12GA? 10GA? Is insulation necessary? IE. Could you use 10GA solid copper ground wire? Great video...thanks!
If I was to use 12 gauge wire to build it with would that change the measurements any. Reason I ask is because I have some 12/2 left over from a addition I just got done with
Add 3/4 ground radials 1/4wave length long on base part of J Pole straight horizontal. mount antenna on a insulated pole ,so antenna floats. Ull find it will perform a lot better line of sight and better performance. I built one for PMR446 band ,works well.👍
The mil spec seems to have changed on 12, and 14 gage since the 1960's. 14 awg appears to be slightly heavier, 12 awg slightly thinner.. the older 12 awg wire is near near todays 10 ga!..about .018" difference. Which could change the space between the elements and fitting into thin wall pvc..
Yes. In fact, I outlined such a setup for 2 meters here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lpilADTKD6k.html You will need to use smaller diameter coax (RG174 or similar) and adapt to your handheld as needed.
The ends of tape measures are sloppy for inside or outside dimensions to take into account for the thickness of the metal tab at the end of the tape measure
I agree SWR should be lowest where you transmit, but I spend most of my time on simplex. Final tuning should always be done with the antenna mounted in it's final location...
If hitting your local repeater is not too difficult, you still may want to tune for best resonance at 462.6, because simplex to 5W handhelds is a lot more difficult than duplex to 50W repeaters.
Hey guys its a simple end fed half wave antenna , that 1/4 wave lower section is only for matching the feeling impedance it's pretty much set at your coax impedance 50 ohms in this case , that's all this end is for. Now the portion above the j section is your radiating antenna it's the part that you trim for resonance if the frequency is to hi you need to add to it if the frequency to low trim off an 1/8th of an inch . now after you get an acceptable swr
Thank you for doing this build video. Saved me a lot of trial and error and I managed 1.07 @ 465 MHz after 2 trimmings. 🍻 Also…(fyi) The “slop” that’s in the hook end of a tape measure is designed to make up for the difference of when you measure by hooking the end over an edge, versus butting the hook up to the edge. The amount of movement is equal to the thickness of the hook material and yields the same measurement regardless of how it’s used.🫡
@@ricksshop Good idea.. Thanks! I think this is a great first scratch antenna project! I am curious why this one is so much shorter than Ed Fong's GMRS JPole.
The average person like myself isn't going to buy a Meter just for a single antenna installation. Great video otherwise. I'm looking to install a simple base antenna for my HT GMRS radios to use once in a while.
You did a very good job it come out very good and you could attach to the top of the antenna a line and put it up in a tree and get quite a bit of heights out of it so I enjoyed watching if you have any more intelligence available I’ll be watching god bless
I did some experimentation with wider and narrower separation, narrower seemed easier to tune. Part of it is the unshielded center conductor and ground become radiators, and that becomes more of an issue with UHF.
@@ricksshop Thanks for your answer. I was thinking of using the J-pole antenna with a scanner, one frequency only. Maybe it's less critical then. Given that I have bought copper pipes and t-joints it's kind of hard to design it with so tight separation at 469 MHz . It seems easier with a house wire.
Sorry cat sent last message before I was finished. After you get an acceptable swr reading You can assemble it in the tube but it's not going to be trailer omni due to several factors although is should be satisfactory , you need a choke on that coax to keep it from radiating although most people don't .now after you get it all ready to use try turning that antenna wile watching your field strength meter or s mater and you will notice its not omni so just turn it to get strongest signal on station you need and lock it down . This antenna is a full 1/2wave so has gain in fact we measure all antennas from this half wave figure. It's a great antenna and there are many copper Jr pole antennas over 50 years old still working fine. Build your antennas guys is the best was to go.
Hello Rick Thanks for the video and clear instructions. I meticulously followed your instructions and when it became time to test on my nanovna I got some real crazy results. I took the antenna out of the 200 psi PVC tube and I got reasonable test results. As soon as I slip the tube on, even just a couple of inches my test results flip out and shot up over 5 to 1. Take the tube off and then I slide down to 1.20 : 1.00. I double checked all measurements including the 5/8ths soldering points and everything is on the dot. Can you make a suggestion? Thx Tim KI7JBF
Expand the frequency range of the vna. What is probably happening is the PVC is changing the velocity factor of the antenna and pushing resonance lower...
@@ricksshop wow! Funny thing, I had set my range on my nanovna right to the parameters of the GMRS band. I will try this in the morning and reply back. Fingers crossed. Thank you for the super fast response. Happy New Year!
I might in the near future. 2 meter J antennas end up about 6 feet long, and the radiation pattern isn't optimal on 70 cm. Ed Fong builds an admirable 2 meter/70 cm dual bander that I won't copy, because he sells them for a good cause and encroaching there violates my ethics.
Sure! I did exactly that in the two meter version here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lpilADTKD6k.html Remember though, with bare copper the velocity factor changes and the wire dimensions will have to be a bit longer.
I'm new to J-pole and you made this look so easy! I had some 14-ga Romex left over so I grabbed that (and cut and bent to your dimensions). After sliding into 3' PVC up to the end, my NANOVNA showed resident freq at 471mHz. SWR was around 1.3:1. I was like, Ok, let me trim the ground a bit and the SWR went down, but the freq went higher. I thought maybe the 1/2" Wave portion was too short, so I built another longer version. I get the same 471mHz, but the SWR was around 2:1 .. what am I doing wrong? I wanted to center my freq around 465 (due to more repeater usage but still wanted to use Simplex.).
Sounds like it was close with the first iteration. Full disclosure, the J pole in the video was my fourth attempt. The lengths at UHF frequencies are super critical. Try adding 1/8" to the short leg and 1/4" to the long leg and retest. Velocity factors for insulation and PVC vary, which might account for the discrepancy.
@@ricksshop Thanks! I also just noticed on my 2nd try - the POS+ solder joint was around 1/8" higher than 5/8" - I'm betting that has a lot to do with it as well ? mismatch ? -- Tim N
The other thing that could be affecting your SWR is the type of PVC pipe you are using. Ideally, you should be using 200psi thin wall PVC. They sell it at HD, Lowes, Ace, etc. Also, apparently certain kinds of paint on the PVC can mess with SWR as well. I painted the pipe on one of my tri-band j poles with Rustoleum rattle can paint to camouflage it a bit and it killed the SWR of the antenna. Had to buy all new PVC. Ended up just leaving it bare. I've heard Krylon brand doesn't mess with SWR, but haven't tested.
@@SirRonmitTheoretically changing the tapping point only changes the feed point impedance which does affect SWR. my approach would be to adjust the lengths to adjust resonant frequency as per the video and make a final adjustment by shifting the feed point a little. The low SWR figures that were shown in the video indicates that the position at 5/8 inch is fairly accurate.
here in Australia we have 2 C.B. bands, globaly 27mhz and localy 476.425 mhz to 477.400, this was 40 ch @ .025 spacings now we have 80 ch @ .0125 spacings, repeaters are offset @ +.750 from ch 1 to 8 and also 41 to 48 i use a J-pole plus other multi-gain ant 6db and 12db, O' just as a foot note ' Australia, new south wales police 467mhz - 469mhz multi-channels through-out the region LOL so' leave you GMRS at home when comimg to Aus ....cheers
I assure you, it was most deliberate. Changes in velocity factor, wire type, pipe used, installation location would all change the length of the final antenna, which is already difficult because of the UHF frequency (1/4 wavelength is only about 6").
It is. Antennas designed at DC ground are common (and desirable for lightning and noise suppression). At 460-ish Mhz that dead short becomes 50-ish ohms.
Oh, FFS - the blade at the end of the tape moves so it can accurately measure inside and outside dimensions. It moves, you’ll discover, exactly the thickness of the blade.
The 1st inch of tape is 1/16" short. When measuring the outside dimensions, the tab moves 1/16" away from the tape to extend the 1st inch to an inch long. When measuring the inside, the 1/16" thick tab moves towards the tape to make the total 1st inch an inch long. It's not "sloppy".
Why not use 1/2 copper pipe and build a real J Pole antenna. Its all about antenna GAIN people and 14 gauge wire is crap. Do things right and get good results with the right material 15.00 tops for a good copper J Pole with high gain do not use 14 gauge wire this is crap.
Incorrect, especially at UHF. The only thing that changes with thin conductors is bandwidth, but GMRS isn't that wide. Also, my personal opinion is copper J poles look about as redneck as an antenna can get.
You are mentioning ham radio is this for ham or gmrs?I'm GMRS all the way! I transmit on 462mhz I don't have the equipment can you make me an antenna? If so How much will you charge?
This is a GMRS antenna. If you want to purchase a ready to go antenna, my suggestion is to get an Ed Fong GMRS antenna. They are very similar to what I build and work well.
