Ham Radio: 40 Metre Dipole In A Small Space

[@KarlWitsman]

I used an antenna like this for years, indoors, and it worked great for SWL, receive-only. I modelled it after a similar antenna that we built inside a Radio Shack store to demo shortwave radios. Even inside the store, we could pick up stations from all over the world.

[@timg5tm941]

Just shows they work 👍

[@jeffreywonser3241]

I'm a relatively new HAM, and how antennas work is still foreign to me. But, I'm starting down the rabbit hole, and this video was AMAZING for me! Thanks, Tim! 73's from K9WNZ!

[@timg5tm941]

Glad it helped!

[@HamRadioDX]

Great explanation Tim. You’re videos are very informative as always. Keep up the good work 👍

[@timg5tm941]

Glad you like them Hayden and likewise!

[@michaelmohr9700]

Thank you Tim for this video. Thank for the nice detail about this use of 450Ohm Ledderline ! vy 73 de DL1AQU Michael

[@timg5tm941]

My pleasure!

[@m0aze611]

Apologies Tim, I missed this one. Very interesting, via people like yourself KZbin has opened up a great mechanism for having a go! Regards Mike

[@timg5tm941]

Cheers Mike! 73

[@chrismosquad1056]

Bravo, mate! Excellent video! Thank you for posting!

[@timg5tm941]

Thank you!!

[@robinedminson6461]

Really informative. Might have a good look into this but with much wider folded section, 100-150mm. MMANA, here I come 😊

[@timg5tm941]

I am sure you will enjoy the experimenting!

[@cuban9splat]

Very good antenna design. I agree that the "real" test of antenna performance is on the air. It always amazes me the things some go through to squeeze one more db of gain out of an antenna. The difference will be unnoticed at the receiving end. Great job, Tim. 73 de K7RMJ Frank

[@timg5tm941]

Absolutely agree 100%

[@alvarogaitan2529]

Great job Tim 73 from kb2uew

[@timg5tm941]

Thank you!

[@Atomshamradio]

Great introduction on that antenna 👍⚛

[@timg5tm941]

Glad you like it!

[@davem0udb]

Like this Tim, I’m looking to do the same, but feed it with ladderline, linear loaded doublet. The length will be whatever i can cram in. keep up the good work. m0udb

[@timg5tm941]

I’ve done that and it’s ok!

[@williamgrocott8925]

I’m trying the same Dave. I am experimenting with 2x13m legs (Linear loaded to 7m per leg) fed with 300 ladder line. If it works it would make a really nice portable light weight multiband antenna. 73 de Will, M0LGW 👍🏻😊

[@gbamck]

Interesting, Tim. Nice one 👍

[@timg5tm941]

Thank you Mick!

[@robinmarwick1982]

Really helpful video Tim thanks.

[@timg5tm941]

My pleasure!

[@tangobayus]

Have you tried a quarter wave dipole? I've seen some comments to the effect that it will do almost as well as a half wave.

[@kitesurf58phil]

I've made a scaled up version of this concept, using 300 Ohm slotted ribbon, for 80m to comply with the ERF rules in my 30m x 6m plot. When I noticed that as a fully folded dipole it was also the perfect length for a 60m antenna, I decided to feed it with 300 Ohm ribbon as a doublet. I was looking for a way if electrically shorting the gap for 60m and considered an 80m trao but this would have a shortening effect so I have left it alone. I'm having great fun on all bands from 80 to 10m and enjoying a lower noise level than I had on my big inverted L. I don't know how much difference it makes but the gap on my linear loaded antenna is at the top above the feed point. It was bang on resonance at the design frequency of 3.75 MHz and required no other adjustment. For the higher bands I'm using the trusty old SEM TranZmatch to load it up with good results.

[@nishanthak2451]

Informative 🎉

[@timg5tm941]

Thank you!

[@acestudioscouk-Ace-G0ACE]

Thanks Tim, this has been very useful. I need to make an antenna for a friend who is restricted to using his loft space and am considering using something like this as a starting point.

[@timg5tm941]

Ah right 👍

[@williamgrocott8925]

Great work Tim. Very insightful and I will try the same with a doublet and 300r ladder line. 73 de Will , M0LGW 👍🏻😊

[@timg5tm941]

Thanks! Hope you enjoy the experimenting and usage!

[@brian.7966]

well done Tim, Its always good to look at your antennas. many thanks, best of luck in the new year.

[@timg5tm941]

Thanks, you too Brian!

[@robertvandersanden]

Nice idea to shorten an antenna this way but is it practical? A short (

[@timg5tm941]

Well I can only describe what happened in practice and it worked well as a mono band dipole. Thanks for the information 👍

[@DonDegidio]

Hi Tim, I like the way you put the antennas to use after you model them. Was hearing you today in SE PA when you were mobile on 14209, but not enough for good copy. Stay safe. 73 WJ3U

[@timg5tm941]

Ah Don that’s a shame … next time!

[@Orthodoxuk]

How did you effect the tuning? Cutting the ends or reducing the foldover? What was your tuning frequency?

[@pc4ad]

Hmm.... Brings me to an idea. I have some I think 300 ohms ladderline laying around. I might use that at the end of my dx-commander-40m-with-coil-for-80m wire... If it get's a little warmer that is.

[@timg5tm941]

Nice idea!

[@Andrew-yx7sf]

I am going to try a linear loaded vertical using this method. Feed one side of the ladder line up the pole and back down. Basically just using one leg of the dipole with some radials.

[@timg5tm941]

Yep done it and it works.

[@beppecavagnoli3994]

Hi Tim, thank you for thi video. Wishing you and your family a happy easter, i want ask you how is connected the 300 ohm ladder to the coax cable and to the dipole wire because in the video i cant see in detail. Thank you if you will write an answer. 73 de Iu2mke

[@timg5tm941]

Hi - if you mean the two dipole legs - the top part is connected to the antenna wire and the bottom part is left open. Remember to short the two wires at the end to complete the circuit for each leg. 73

[@M7NGY]

What software / site do you use 8:31 to work out equations please

[@timg5tm941]

Hi there it was MMANA-GAL modelling software

[@johnbaldwin9126]

Hi Tim Thank you .I have ordered from Amazon in the uk and my daughter will post the ladder line to me...more expensive but at least i will have it...thank you for your comments...john

[@timg5tm941]

Great stuff 👍

[@radioguy19510]

Great video as always. Thanks...

[@timg5tm941]

Thank you!

[@keithfrost1268]

I keep coming back and rewatching this. I've got a small back yard as well. so, what I'm wondering is could you use the linear loading to add 40m to a hexbeam?

[@timg5tm941]

Now that is a good question

[@trooper2221]

So, open loop has what advantage if any from the closed loop versions I see? Thanks

[@M7BCN]

Brilliant, Thanks Tim.

[@timg5tm941]

Thanks mate!

[@darylcheshire1618]

love Shaun The Sheep on the right

[@timg5tm941]

Thanks!

[@Thermopylae2007]

I have used VE3WY's shortened antennas from Maple Leaf Communications with great success. Using Tim's video on calculating antenna space for an inverted v I was even able to fit the 70foot 80/40m version into a tight space. Thanks!

[@timg5tm941]

Thanks for the info! I like his designs and I will try and replicate the 40/20 shorty once we have more daylight here.

[@Thermopylae2007]

@@timg5tm941 I spoke with Bob in the summer of 2020 and it seemed as though he was already winding down the business for retirement, but see that his website remains up and unchanged. It's probably not a bad idea for those who'd want to order his originals to try and get them while still available.

[@timg5tm941]

I agree. I contacted Bob last month about the 20/40 and he confirmed he had stopped making them. But he was still kind enough to answer a query I had about it’s dimensions.

[@Orthodoxuk]

How about the same idea for 60m where the nvis is important for inter-G working?

[@lmachielse7077]

Hi Tim, I m from the netherlands , i have a small garden from 33 feet long, how long is the 300 ladder line? thanks great video Lauw

[@timg5tm941]

Hi there Lauw, for the antenna legs - about 7m or a fraction more per leg,

[@Graeme_Lastname]

For the difference between model and real, did you have control over the ground plane?

[@markhall3434]

Gosh.. Thinking a directional cubical quad.. how small can I make it.. 3 elements.. Balanced Tuner is fine. Phasing lines to reflector/director? Maybe I could do resonant loops with tunable caps? I can do at most a ~30' boom. More that a TV rotator, but no king kong required.

[@timg5tm941]

Sounds a lot of fun!

[@PatAutrey]

And the follow-on question would be what would happen if you had two ladder lines per side effectively having four wires that were linear loaded has that ever been done and do you know if it would work as well as the three-wire version

[@timg5tm941]

Yes possible .. check out the cobra dipoles

[@dxscotland5901]

Enjoyed this1 Tim and might try an inverted v for 80m! Thanks for the great videos 👍 73 Gm4zji Chris

[@timg5tm941]

Good idea! Around 92 feet as a starting point for the ft8/cw end

[@TheHamshack]

Great video thanks

[@timg5tm941]

Thanks!

[@johnallen6440]

I built a version using 300 ohm ladder line, 22 feet each side. VSWR is higher at the CW end and goes out of band at the top end before it rises up. Perhaps 23 feet either side would have got the whole band covered better. I built it for UKBOTA configured for NVIS. A nice easily deployable portable antenna.

[@timg5tm941]

Good sounding solution!

[@2E0LMI]

Thank you, your video has given me some ideas. I have an inverted v fan dipole in my loft for bands 10m to 20m. Have been thinking of adding a 40m element. I was just going to zig-zag snake the legs to fit it in the loft, but this might be a better option? ..better as in neater I mean, as you may be able to imagine the teepee fan of wires for 6 bands (inc 11m) up there is getting a bit difficult to navigate safely through when making adjustments. No problem with rain on the ladder line as indoors :)

[@timg5tm941]

Good points 👍

[@Brenda-jf2pe]

Keep making good videos, we are all still learning ! COVID prison gave me the study motivation to get the General. I’m working on the Extra just for the frequency’s we need more videos everyone needs more Elemering! JohnBoyUtah KJ7TBR 😎🇺🇸📡🎙

[@timg5tm941]

Thank you!

[@puntofisso]

Hi Tim, thanks as ever for your very informative videos. One silly question: when you say mounted at 5m, is that the top central bit (with the balun), or the bottom of the ladder line legs? It the former, which is what seems to be the case from the picture in the video, do you use poles to stick the ends of the ladder line in such a way that the V keeps its shape? Thanks, and 73 G1WNZ

[@timg5tm941]

Hi there - the modelled version is a 5m flat-top dipole so same height throughout 5m agl. The one I have used was an inverted-V with the apex at 8m agl and the ends at 3m agl. Little difference (none in real world) between those two on 40m. 73

[@puntofisso]

@@timg5tm941 thanks Tim :)

[@johnbaldwin9126]

Hi Tim...Im in Thailand ,Where can i buy ladder line as I cannot see any even on E Bay and Ali Express?

[@timg5tm941]

Hmmm not sure must be some ham outlets there?

[@johnbaldwin9126]

@@timg5tm941 Hi Tim No...maybe in Bangkok but 450 miles away....I will look thank you for your reply ...john

[@timg5tm941]

Maybe they’ll deliver?

[@DougNetherton]

I would be interested in knowing if you could tune this antenna up on 15 meters easily? Could you use this feature as the wire element for an EFHW antenna? Doug VE3MCF

[@timg5tm941]

It won’t have the same harmonic relationship as a conventional 1/2 wave 40m dipole. I can’t remember but this one might be up around 25-27 MHz maybe?

[@redstickham6394]

Great idea for limited space. Does work multiband if fed with twinlead or ladderline using a tuner?

[@timg5tm941]

Yes it will work on the higher bands - not sure about the radiation pattern though. If you want say 40-10m then a 44 foot doublet fed with ladderline could be a good alternative

[@redstickham6394]

@@timg5tm941 I'm trying to build a multiband antenna in my attic space. I wanted to build a 40-10 doublet but trying to figure out how to snake it around. This might be a better alternative.

[@PatAutrey]

Hi Tim I built the ladder line doublet with the extra wire woven in between the windows of the ladder line so it is a three-wire linear load. Would it accomplish the same thing electrically if I just connected a ladder line and a single wire as a fan dipole instead of interweaving that extra wire just leaving it separate and isolated but still emanating from the same connection point

[@timg5tm941]

Possibly yes

[@DonzLockz]

So is this a mono band at 40m only? Have you tried 450 ohm laddeline as a feed line also?

[@timg5tm941]

Absolutely - many times and works well

[@seanfoley7097]

Here's a question which is the better antenna the linearly loaded dipole or an efhw antenna

[@timg5tm941]

Depends on configuration. The full sized 66ft efhw will be more efficient

[@stewartrv]

Ahh the 131.234 foot band! 😀

[@timg5tm941]

Indeed!

[@johnpeterson7264]

Great video ! I’m wondering if I could apply this concept to create a shortened vertical dipole - perhaps 3 wires rather than 2, fed then half way up the mast, to create a lower angle of radiation.

[@timg5tm941]

Yes - I have made a video on this two years ago - a third wire for both legs vertically polarised and fed with coax as a vertical dipole. You will be around half the size of an orthodox halfwave dipole (or near). I found using a third wire got me 15m with an 11 foot long dipole. Reduced bandwidth but it provided a useable SWR. Have a try! 73

[@johndickinson8848]

Why did you use 450 ohm ladder line and not 300 ohm ? Thanks.

[@timg5tm941]

Wider spacing so the antenna can be a little shorter. You can use 300 ohm but as the wires are closer the antenna will be a bit longer.

[@johndickinson8848]

@@timg5tm941 Thanks Tim. Do you know the length when you use 300 ohm ?

[@timg5tm941]

@@johndickinson8848 I don’t but I’ll try and model it some day

[@johndickinson8848]

@@timg5tm941 Sounds good. Also, what was the length of the gap in your antenna ? Thanks.

[@timg5tm941]

About 20mm I think John.

[@chillychurchil5972]

can i use 300 Ohms tv arial antenna wire..similiar to 450 ohms ladder wire

[@timg5tm941]

Yes but as the wires are closer together the overall length of both legs may need to be longer. A few extra feet and trim the wire that returns back to the centre on both sides should do it.

[@PatAutrey]

Hey good afternoon Tim hope you’re having a wonderful day I was wondering if you would share your opinion on what is considered to be the best iNVIS antenna For close range local contacts between five and 100 miles

[@timg5tm941]

Hi Pat! For 80m? Low dipole say 15 feet above the ground

[@PatAutrey]

@@timg5tm941 well I actually want to be able to do it for 80 m 60 m and 40 m so are you thinking a tri-legged multi band dipole all emanating from the same 1:1 Balun?

[@timg5tm941]

@@PatAutrey yes or one dipole (doublet), around 90-130 feet fed with ladderline.

[@PatAutrey]

@@timg5tm941 How high do you think the doublet needs to be

[@timg5tm941]

@@PatAutrey for nvis, same as the dipole above

[@jonthebru]

Now do this for a 60 meter band antenna. That is a little used band with limited bandwidth but to have a resonant antenna would be very helpful.

[@timg5tm941]

Great suggestion. My suggestion is that as a 60m 1/2 wave is about 88ft, that a 62ft version should be near the money for 60m.

[@jonthebru]

@@timg5tm941 I realize it's not a heavily used band, but the interisland nets use it here in Hawaii, NVIS style. I have a 40 meter dipole that I'm making into a 40-60 fan dipole, 40 is also used for the local nets of course. I'm still working it all out. Good thing is I have lots of room.

[@timg5tm941]

Good stuff John. It’s a great band.

[@g0fvt]

Intriguing, particularly when you consider it as inverted V with a 45 degree slope from the apex, 70% of 70%. Would give you a halfwave dipole in a quarterwave space... 73

[@timg5tm941]

Good point

[@bhenry5091]

Bob's store is Maple Leaf Communications.

[@timg5tm941]

Yes - that's the one

[@vu3mes]

Sharing..73

[@timg5tm941]

Thanks!

[@ssubaihi]

You tell a lot of Antenna Secrets

[@timg5tm941]

Thank you

[@radiolinux45]

Please can work out for 60 meters liner dipole loaded ?

[@timg5tm941]

Using the same principle of 70% the typical length I’d look at around 62 feet.

[@radiolinux45]

@@timg5tm941 please can tell full length in metric I live in town house only small back yard in SW Cumbria De G0MEJ 73's

[@timg5tm941]

@@radiolinux45 try 19m in total. So 2x9.5m legs linear loaded using 450 ohm ladder line. Should be near 5.3 mhz

[@Kartrampage]

Why u use not metric system?

[@timg5tm941]

These days I do - my bad

[@ManuelPinner]

Inside a Apartment, a Magnetic Loop Antenna Works very Well,

[@timg5tm941]

Indeed

[@kc6nfv746]

Nice video now if any one want to put up a full size diepole antenna in a small yard watch my 80 meter's Z Antenna video it fit in the same yard you put a 40 meters full size antenna in the same idea can be used for a 160 meters math formula 468 divide by the FRQ for each side for the antenna 234 divide by the FRQ

[@timg5tm941]

Nice

[@DiggerD-w6r]

No garden. Indoors only.

[@2EOGIY]

bow tie?

[@timg5tm941]

An option 👍

[@kn9ioutom]

TNX FOR GREAT VIDEO 73 DE K9IOU

[@timg5tm941]

My pleasure!

[@KS6DAY]

Thanks for making this video. This looks like an excellent solution for my needs. 73 de KS6DAY.

[@timg5tm941]

My pleasure, thank you very much for watching and commenting 73

[@glenmartin2437]

Thanks for the information. N0QFT

[@timg5tm941]

Any time!

[@kitesurf58phil]

I've made a scaled up version of this concept, using 300 Ohm slotted ribbon, for 80m to comply with the ERF rules in my 30m x 6m plot. When I noticed that as a fully folded dipole it was also the perfect length for a 60m antenna, I decided to feed it with 300 Ohm ribbon as a doublet. I was looking for a way if electrically shorting the gap for 60m and considered an 80m trao but this would have a shortening effect so I have left it alone. I'm having great fun on all bands from 80 to 10m and enjoying a lower noise level than I had on my big inverted L. I don't know how much difference it makes but the gap on my linear loaded antenna is at the top above the feed point. It was bang on resonance at the design frequency of 3.75 MHz and required no other adjustment. For the higher bands I'm using the trusty old SEM TranZmatch to load it up with good results.

[@timg5tm941]

Sounds a great set up!