Ham Radio - The simple coax cable emergency prepper antenna.
HTML-код
- Опубликовано: 28 авг 2024
- An old design that many new hams may not be familiar with. Easy to build with minimal tools, great emergency throw-it-together antenna.
If you like my videos, please subscribe here: www.youtube.com...
If you want me to keep making more videos like this, consider becoming my patron at Patreon: / kb9rlw
Discuss this and other videos on Facebook: / kb9rlw
Hit me up on the echolink repeater down by my house:
W9TE (Node: 519521) 
Наука
Made a dozen of these for members of our search and rescue group. Everyone carried one in their pack along with 50ft of paracord to hoist it into a tree for height. They work excellent!
Kevin, I watched this video a few years ago, and really got interested in making antennas. Havent stopped yet. Thank you for much a clear understanding of a video. A+
Back in the 60s I remember My Dad using something along these lines when we went camping. He used large clamp-on fishing weights instead of a bolt.
This works great I hit a repeater 50 miles away! I love it.
I had a homebrew 2-meter antenna that was constructed with an SO-239 and (5) lengths of solid wire. I had it mounted about (12) feet up on the side of my house. I knew it would work, but I was surprised at just how well it worked. It was nearly free to build, only took a few minutes, and it would probably have taken a tornado to bring it down. It was there, and still working perfectly for over twenty years. I finally rented the house, and for all I know, it's still there! If only HF antennas were that easy. *lol* Thanks for the video. A new subscriber here.
well done! that video really opened my eyes to the simplicity of what an antenna can be.
I already understood the basic construction of "the dipole" antenna and instantly
said to myself "vertical dipole" brilliant work you have shown. I overlooked that simple technique
often thinking dipole antennas were limited to horizontal polarization and directional operation.
you have opened my eyes to how easy an antenna can be made, thank you again! I can't wait to try a construction of a 2 meter "field antenna" emergency build
it worked! I built this antenna for FM radio reception (98 Mhz, 750 mm long each end, 75 ohm coax cable), and it improved a lot in my stereo set. Congratulations for the video, it is very informative and simple, just what we need in real life... At a local electronic store (in Spain) they told me that they weren't selling FM antennas anymore... You saved my radio, thank you very much.
After stripping out the coax inner, check the length of the empty braid! I guarantee it will be about 120% longer than the inner, if you have accidentally pulled it flat! Answer?: compare the length to the inner and snip off any excess braid! The VSWR is also helped by dressing the coax at a right angle to the line made by the inner/braid, and putting a few giant ferrite beads over the coax sleeve at the feed point (can often be stolen from old computer video/USB leads!). Both help to prevent the coax feeder radiating and spoiling the SWR.
Thanks for this tip!
if you offset the shield length a little longer by about 5% you can get the VSWR lower. The overall length can stay about at the 38" length but by making the antenna longer, you can tune it very well by folding each end back on it's self and retest the VSWR.
Very common antenna used in hang gliding. Center conductor runs up the harness mains that you're hanging from. The Shield runs back along horizontally on the back of your harness. Works very well. As you can imagine, range while airborne is very good.
You just made a vertical dipole! Nice! Add a balun(multiple coax turns) at the bottom after the braid ends, this should remove the hiss and reflected rf in the ur shack
Thatnks for your video! In the 1990's I was assigned to go to a local hospital and establish comms during a search and rescue drill. I found that inside the hospital where I was told to be stopped my rubber duck antenna from getting into the repeater. I made one of these little dipoles for 2 meters with just a pocket knife. I borrowed some tape from the nurses station and taped the braid back onto the coax so it was just one line. The nurses were able to open one window about an inch at the bottom and I dropped the antenna out the window and down a few feet. It got me into the repeater very well. During an antenna building night with our club I had built ground plane antenna and knew that from the crook of my elbow to a certain spot on my hand was 19.25 " . That came in handy building the antenna at the hospital.
Very MacGyver! Good practice.
I live in Melbourne (Australia) and I like to listen to 91.5 FM which during the early hours of the morning and late evening is PLAGUED with STATIC. I had tried various antenna fixes ex. you tube and decided to give yours a go using the 75cm dipole length from another on line calculation.
Set it up behind the bed head and now almost static FREE and yet the radio signal display is much the same.
Sure beats listening to the alternative new wave crapolla.
Thanks for your highly informative and educational clip Kevin.
So, I watched this video, acquired all of the necessary components and built it. Works amazing! Thanks for the SHTF comms idea!! 🤘
A ferrite bead at the feed point would help quite a bit in energizing that shield side of the dipole. A snap on noise choke would suffice in a pinch. Also, check the length of the shield. After pulling the center through it gets a bit longer. This is a great antenna in a pinch for new ops. Thanks for sharing. Your video problems sound like mine. 73
This was awesome. My interest in radios and HAM in general is mostly for readiness, so this would be an easy build to have in a kit or bag. Really cool. thanks!
Hi, thank you for the nice video and showing that you do not need big bucks to antenna and ham radio really.
In my early days some 40+ years back I used to construct a similar antenna but instead of slipping out the center conductor from the side, as was in your video, instead I rolled the braid down on the coax . It is still a dipole but in so doing the coax does not interact with the dipole as it comes out of the lower end.
Well done and keep up the good work Mans 9h1gb
Even in long runs, 75 ohm coax is okay if you're receiving. I had a 200 foot length worth of rg6 and it worked great on lower bands.
I was gonna ask how long for a cb antenna, but then you told me. Thanks for an incredibly informative video!
Many Thanks!
I live on top of a hill and snoop on HAM, air + airports, some rubbish on CB, taxi companies, truckers etc. using Uniden scanners
This quick aerial construction has made a clear difference from the small stock units that are on top of the house, and your aerial is indoors!
I'll look into different aerials I can now make - Cheers
Stupid question i know, sorry I'm new... But i also avidly listen to scanners. Would creating this increase what I'd be able to hear on my scanner? I have a little ducky for my scanner.. This looks super simple
@@Majestiicc12 I've only put this inside my house (in the attic) and it picked up Blackpool ATIS 127.200 immediately, which is approx 40 miles away. I have a ducky outside my house, on the roof, and that has never picked up that frequency before with enough strength to hear it clearly. The ducky will pick up other frequencies though, e.g. GB3FC's repeater 430.850, which is the same distance away in the same direction very clearly (N.W.England)
I'll put this on the roof and do a test one day + make a couple of different aerials to try out
(btw: I'm also very new to this!)
@@TheVicar thanks for getting back to me! Hey if you are new as well, by all means shoot me any information tidbits you think are useful as a newbie 😂😂😂 thanks!!
@@Majestiicc12 A couple of things I've noticed that maybe of use is that 1 of my PC's is near my base scanner and will cause a lot of background noise, its approx 1 metre away from the scanner and the coax leading away to the different roof and attic aerials - so turn everything off in or near to the signal cable and base unit, also look what the coax goes near on the way to the aerials - test, test, test! And also check all connections and have quality cables without any corrosion - seal against rain to stop any shorts and/or rust
Secondly the aerial constructed from this video made a lot of difference to the 127.200 signal i mentioned earlier. By mistake I noticed even more quality to the signal when I stood approx 1 metre behind the aerial. The aerial being inbetween me and the ATIS transmitter, which is 40miles away. Is this bounce back of the signal or am I shielding in some way? I replicated this slightly by putting 12ft of 1cm core aluminium (under the road mains feed cable that goes to a house), bent double so it stands at 6ft tall where I was stood - it didnt work as good as the human body, but it did improve the signal. How, I dont understand
(The mains cable was found in a hedgerow, after electrical works near my house when all the road was dug up. That was a week after I'd subscribed to Kevin Loughin's channel and I thought, that will come in useful for practicing making some aerials! I've stripped off all the thick copper wiring, some bare, some covered and the centre being a covered nearly 1cm thick solid aluminium core - I've got some quality free wire to play around with! Heavy to carry but what a bonus find)
Also as I've heard people on amateur radio say frequently, its all about metal in the sky. So I put a seperate 20inch 164-174 MHz Taxi/PMR aerial on the roof of my house. The original aerial that came with the Uniden UBC355CLT base unit was a 22inch conventional extendable metal unit, but I've only ever attached that to the rear of the base unit which means that aerial has only been tested indoors. The handheld is a Uniden UBC125XLT using a 6inch ducky, which is really good for military airshows, but also works really well when connected to the roof 20inch PMR
I need to try lots of different aerials as I briefly talked to M0ICK (an amateur radio guy) recently as he was parked near my house with a huge aerial some weeks ago, during a RSGB VHF radio contest. A sound guy! The aerial he had made me think I need to look up aerials on youtube and then I found Kevin Loughin
Weather conditions make a big difference and thats where internet repeaters make a big difference I guess. Listening to people in New Zealand talk to people in the USA when I'm listening to a repeater in the UK is cool
Thats everything I know so far. But there's so much to test, learn and understand!
@@Majestiicc12 Check out this vid: ruclips.net/video/fbOY3OADpo8/видео.html
There's a lot to learn but there's free software in this video to test aerial construction
I've made several of those, to get people on the air, I've also doubled the braid back down the coax (fiddly!) To make it somewhat tidyer and allowing the antenna to be fed from below.
these antennas work surprising well.
Now that my friend was an awesome video!!!! I'm just getting into ham and you made it in a way I could understand.
I really like how you presented this and how easy it looks! I am just getting into radios so looking forward to trying this out.
Great video, think I will toss one of these together to put in our RV to use when we are on the road, and overnighting in a rural hide a way.
This is the second time I watched this video. It was a good refresher for me. Great job!
Great job man! I just did this for my Vertical. Only went 3 ft. up, TREMENDOUS receive distance. Indoor window mounted. Thanks for the vid 😊
Wow, Thank you for sharing. I am new and overwhelmed.
I am glad to see that I am not the only one who occasionally does not actually get what they wanted recorded, I did it again this morning and one last week as well. Thank you for sharing this video with us, I am going to try this out in the field and see how well it does. Thanks for sharing and thanks for sharing the chart with us as well.
Thanks and have a blessed week.
Dale
KI5ARH
Excellent video, thank you! Getting back into SAR, I will absolutely be building one!
Hey there!
Thanks for sharing!
I was doubt about it but now I'm shure it is works.
Bye for now
Hi Kevin, I used to make a similar antenna many years ago but I would pull the shield down over the outer covering of the coax, I believe it was called a co-linear antenna. After watching your video I was reminded about that antenna, I am going try that again for my Go Box, I'll also make one like yours as well. Thank You for the video. 73 Kevin VE3RRH
This...is pure gold information. Thanks!!!
Very cool, thanks for sharing!!
Such a simple yet effective antenna and so easy to construct. Thank you!
I'm so new to this hobby that you might as well be speaking Chinese and teaching me witchcraft. When I have bad reception I touch the rubber duck onto something metal hoping it will improve like the old television antennas lol. Or hold it up in the air hoping the extra 3 feet will fix it.
I data dumped so much comms school knowledge after getting out.
Nice video man.
just follow his instructions and enjoy the improvement to your station performance
Good Video. I got a free scanner without an antenna. I have coax to make a free antenna to see if the scanner works. Thanks for using a camera and tripod to make this video.
Take note. The radiating element of the antenna is running perpendicular to the metal corner bead in the wall under the Sheetrock. Not sure what affect that may have had on your test and swr.
I have built an antenna like that before. But I never figured out how to use those BNC connectors. Now i know. Thanks
Thanks. These are the two antennas I've made. I made one for 2M and one for CB SSB.
in 1995 when I got my first ticket. the antenna book then had this very antenna in it.
I remember back in the day when radios had telescopic antennas. They would snap off. A simple wire with alligator clip worked just fine. Just needed to be the right length.
I made one similar to this antenna and put it inside PCV pipe the coax came in to one pipe the antenna leads through a T and out two leads went through 20 inch pipes. Work well vertical or horizontal. Due to sickness haven’t been on the air but need to redo this antenna.
I was poor in high school so I built some antennas. You did it a little definitely then I did. But I think your way looks like a much better method then how I used to build them. But I was only a teenager at the time.
Zappa is the Mother of invention.
..wait, did I get that wrong? 😜
Very cool and easy to remember if ever needed.
Better yet I’ll make one.
*120° angle between the shield & upper radiator element* will provide 1:1 swr @ 0 reactance when cut correctly for center of band, but you may have to wrap a CMC choke in the coax 1/4 wave down from the split.
There's a similar design which does not require using the shield for a counterpoise.
It requires a coaxial CMC choke balun wrapped from the coax at the 1/4 wave point below the cut, which prevents current from continuing down the casing covered shield past the base of the 1/4 wave point, where the current is lowest and voltage is highest.
and they work! Years ago I made one for CB at my cabin and shot an arrow up through a 100 foot tall pine pulling 15lb test fishing line with it so I could pull up the dacron cord with the coax antenna hanging from it, about 70 feet at the top.. I talked over 100 miles away on that and had a 1.2:1 SWR. I couldn't believe how much better it worked than an antorn99 that was up about 50 feet high.
Nice. Take it one step further and secure both ends with rubber bands then slightly pull your feed line until your radials form a V then secure your feed line. In doing so the antenna impedance will drop from 73 ohms (typical of a dipole antenna) to 50 ohms and give you a better match to your transceiver.
The beauty of your wire design is that you can make easy adjustments on the fly and watch your swr meter as you adjust it to get the lowest swr and a perfect match. ;-)
You took words right out of my mouth sir. That's exactly what I was about to suggest to him
He could even spread it out till both are at 180 degrees with each other. It'll work like charm.
Great idea well explained - thanks for posting - I'm off to build one!
Good "How To" video. I remember my younger brother and I making one of these antennas for CB radio many years ago. Good to know!
We can use in twoway radio or not without liscence radio
@@razanmagar574 In the US, if you have a FMRS radio that allows detachable antennas (most of the bubble wrap ones from the big box stores have fixed antennas you can't take off), then yes you can. He had the length listed at the end for the FMRS radios.
I'm not writing about the metric system because that's not what the video is about.
I am writing to say how much i enjoyed the video, it is very informative with a comparison to boot (maybe i should do the 1/2 wave version LOL. I enjoy all of your videos. Keep up the good work.
73 de VE3QJ
Emercmgency Dipole. Great Video sometimes the simplest the better!
Great video Kevin. Really well presented, and full of good tips.
Really really cool
Thank you for the video- helped me a lot!
Ps: you, Sir, need to grow you hair into a ponytail, that would look so freaking amazing!
Just getting into this stuff. Great video and what a great idea!
Excellent presentation. You have brilliantly explained this simple dipole 2m antenna
73
BaoFeng recommends that you need to turn the transceiver off when changing antenna. Mr. Kevin did it without following company instructions. Company says this can damage final stage transistors as they generate pretty good power and without load, they become a toast. Heck! It's his video, his rules!
Awesome..! That's what I'm looking for! 9W8ABM from Sarawak Malaysia 🇲🇾 👍👍👍😍
I like the idea, and will probably have one in my truck by the end of the weekend. However, I don't like the idea of a 1/4 wave antenna. I would opt to increase the lengths of the cuts to 38 3/4" and get the advantage of the theological 3db gain out of a halfwave antenna. Other than that, good job!
If you're going to make an antenna to carry along with you, make the twin Lead j-pole. Much better performance and it coils up for storage. This coax antenna was just an idea for something that could be made in an emergency if all you had was a piece of coax available. Not something permanent that you use and carry with you.
ruclips.net/video/b84ZRGuw1oU/видео.html
Brilliant video very informative ideal portable antennas for the go bag.
73's alan in the UK
Awesome emergency stuff. Thanks! 73
Thanks for this!
I think this would be easier if you simply attached two pieces of wire, 19" long, to the coax. Connect one to the shield and one to the center braid. Shield is hinky to work with - it stretches, and at the contact point, it can break off completely or develop an intermittent connection. I would only go through the stripping process if I had nothing else. If you have nothing but coax, You could also connect a 19" piece of center connector to the shield instead of using the shield as one leg of the dipole.
Well obviously a dipole would be a better antenna for a permanent situation. This was just an idea for what you could do in an emergency situation where all you have is a piece of coax and no soldering iron.
Good content, good explanation, so so video. Maybe draw a spot on the bench to make sure your hands don't float away out of shot.
super camera work
Greetings from Sweden 🇸🇪
Great channel!
You just got yourself a new subscriber 🤖
love the price tag...:)
Actually, you CAN fish the center conductor out of the braid at the center if you take your time and work with a pencil point and you don't have to remove the outer jacket.
I'm going to try this. Thank you!
nice one keven your a top bloke ive lernt a lot from you and it works
Thank you for the information.
Great video Kevin. Very interesting and informational.
Man you nailed it kg6mn
Very well done video! Thanks for sharing with us. 73
Thank you for your informational video.
Thanks for your video. SM5PJJ Jan from Sweden.
Kevin thanks for the great idea and video , I will use this!👍
Kevin, W5BNW here. Enjoyed watching your emergency 2 meter antenna build. After watching I built one and I can hit our repeater which is about 10 miles away but I have to use 5 watts. Works great.
Since I found out that you repair ham radios for people, I have a question for you. I have a Kenwood
TS930S that I am very fond of. I have had it for about a year and everything works great on it, all accept one little thing. I tried to listen to some CW the other night and found that when I switch to CW the receiver gets very quiet, like no audio at all. I can switch to either side band and tune in the CW. I guess it has been like that every since I bought it, I don’t really know because that is the first time that I’ve tried to copy CW on it. I wonder if you would be interested in repairing it? I live in central Texas and I know the shipping will be expensive to Indiana but I would like to get it fixed.
Blu tac big lump on braid end would work really well as a non conducting weight
Well done!
Great video, Kevin. Thank you for sharing such useful information.
Good job well done thank you very much.
Just asking, wouldnt it be easier to snatch up some random electrical wires and attact two to the end of your coax instead of going through the trouble of splitting the coax?
Sure, you could make a dipole that way. The point of this is you could yank out a piece of coax used for cable tv and quickly have an antenna with nothing but a knife.
You could of just relaxed the braid and then just worked it back over the outer jacket, no need to split it.
So cool, thanks. I wonder if the SWR could be fine tuned to even 1:1 in the field by making turns in the coax (slight capacitance change?) and listen for louder static sound on reception (rude swr detector?) or by cutting off or adding on length to the dipoles, LOL, We threw a 25 foot extension cord over a tree limb, clipped an aligator clip onto on of the prongs on the plug and then into tv , worked good enough to watch the big game at the camp out ! *mysteriously after the game ended we lost the signal (do they turn up power on tv towers during big football games? )
Very useful in an emergency...
You could also cut the coax jacket at 38". From the cut-point, measure up 19", snip the braid and remove the upper 19" portion which exposes 19" of center conductor. The remaining braid prevents the center conductor from radiating which effectively leaves you with a center fed dipole.
humaxf1
Really cool stuff thanks
It's been a lot of years since I made a wire dipole. Shouldn't the ground be about 5% shorter than the driven element? I used to hang them in trees by shooting a string with a nut for a weight tied to it up and over a branch using a slingshot.
No, a dipole is meant the be a balanced antenna. If you stray from center, the feedpoint impedance rises.
Oops, I must have been thinking of reflectors in a directional array.
If you are not going to use Balun/match then best the have Dipole Radials come down between 42 - 45 degrees to get 50 ohm in resonance
Really enjoyed the video. What length would you need for 40m 7 MHz, please?
Around 66 feet total length of the resulting dipole. Completely impractical to strip coax that long. Just take two 33 foot lengths of wire and sold the ends to the coax.
How about slinking the braid over the insulation for a Bazooka?
This is a great video.
Cool, I'm showing my lack of knowledge here, but I didn't even know you had to have an equal length of ground wire (mesh) to the transmitting wire (core). I thought the signal wire could just start and the ground terminate at the beginning of the antenna.
Do you use a choke on this antenna and as it's a vertical dipole is it ok fur the feed to not be 90 degrees for a quarter weave?
I don't use a choke. Not needed for lower power and a dipole. The resonant antenna utilizes nearly all of the power, leaving very little on the coax.
You could put the shield at more of an angle, sure, but it will affect the SWR and probably require pruning the lengths to get a good match again.
Awesome emergency antenna, I’m thinking it’s called a T2LT (Tuned Transmission Line Trap) or a variation on that theme.
I made a 17 foot one or 2 sections of 102 inches but I had to use a balanced or air coil to isolate my feed line. Works great in the field( thought I need an 8 metre flag pole. It’s good too see all the theory works for shorter wavelengths. Good job 👍🏼 26CT3250.
Very nice video.. Great job!
I know this is an old video but I just made one of these with some spare RG-58. Allowed my cheap Boafeng to hit all the repeaters within a 20 mile radius just hanging it in the garage. Going to throw it in a tree later.
Is there a way to protect the shielding from getting frayed and destroyed without messing with the signal?
Coating it in something?
Thanks for the video!
If you're wanting something permanent, it's better to make a j-pole, or dipole with insulator built properly and sealed. This is just a concept for something that you can make in a pinch or an emergency if you just need to get on the air and all you have is a piece of coax. It's not meant to be a permanent antenna.
Have you ever tried a small pipe cutter to make those cuts in the coax jacket ?
Seems like it would work well ?
🤔.....?
Pipe cutter blades are generally not that sharp. You need something almost razor sharp to cut through the coaxial jacket without damaging the braid. It's about cutting not pressure. Pipe cutters are about pressure.
Have you ever used a noise suppressor to DC coming up 12volts plus power supply or automotive 12 volts.its great.it reduce noise.
that wood stick on your wall near tardis, i have the same one!!!
where did you get it???
This is awesome!
KI5HFN, thank you! 73!