Off Centre Fed Dipoles - Any Good?

[@roydavis6110]

I use an off center fed dipole. It does a great job here in the U.S. I have it 45 feet, 4:1 balun, 95 feet. It works great 80 thru 6 meters. I have tuned it in on 160 meters. I call a state wide traffic net and from the closest to the furtherest stations no one has a problem hearing me. I have made the same antenna to use portable, in an inverted V. It does very well, no problems. I use a Kenwood TS 590 sg and the internal tuner works out a solution quickly and the communication is great. I have worked over 140 countries and counting.

[@MrCSRT8]

Using a parallel conductor feedline from tuner to fp offers the broadest range of matching solutions while minimizing feedline loss.

[@rickmckee6698]

I use an off center fed dipole that covers 80, 40, 20, 17, 12, 10, and 6 meters. Mine it the 45', 90' version and I don't use a tuner on 75 meters ! What I did was to build a hybrid balun that uses a 4:1 voltage balun (I know most folks prefer a current balun) and I also have a good 1:1 current choke in series with the 4:1 to tame CMC. I first set the initial resonance to 3.450 mhz. The once I got that set, I place a 100pf 5KV cap between the 4:1 balun and the 90' side of the antenna. It was actually already installed but was bypassed by a jumper that I cut once I had the initial resonance set to 3.450. The cap also has a 1megohm 5 watt non inductive resistor in parallel with it to shunt any static charges around the cap to protect it. But once I got it setup and cut the jumper to put the cap in series, the resonant point on 80 meters jumped to 3.810 mhz and the result is that it is 2:1 or under from 3.7 to 4.0 mhz. The reason that I used 3.450 mhz for the initial frequency was that it made the other bands pretty much spot on and they didn't change when the cap was in line. The cap and resistor by the way is inside the box with the balun to keep it out of the weather. I have been using this for 3 years now and it has served me really well.

[@K6ARK]

Your perception is interesting to me. I use an 80m OCF dipole at home, fed 1/5 of the way in from the end with a 4:1 balun. It works on 80m (not well on 75m), 40m, 20m, 17m, 12m, 10m, and 6m with roughly 2:1 SWR or less. It was incredibly simple to build and set up, and I have been able to manage common mode current with a choke on a FT240-43 toroid right below the 4:1 balun. As an unbalanced antenna, it does collect noise a bit more, and some simple precautions must be taken to control feed line radiation. I just wrapped 13 or so turns of coax through that FT240-43 toroid. So I'm not sure why you'd think that's more complicated than the other options you mentioned. In fact, I think it's generally simpler, and it provides resonance on 7 bands without a tuner. Don't get me wrong, it's a compromise, just like any antenna. For a simple, multi-band HF antenna without requiring a tuner, I think it's hard to beat. The closest competition, IMO, would be the EFHW which has similar disadvantages compared to other antennas, and some potential advantages in simplicity of setup based on the location of the feed point. Thanks for the video. Keep the good context flowing.

[@K6ARK]

@Spike S it should work but may affect your radiation pattern a bit. If it's relatively low to the ground it won't matter much. I say give it a try. I'll bet it'll work.

[@K6ARK]

@@VE9ASN I'm not sure I understand. An end-fed "ocf dipole" is an end fed half-wave.

[@richardwesterman5773]

If you feed it 20% from one end, it will have low SWR on 15m and fairly low (i.e., 4:1) on 30m. SWR is high on 17m. If this is not what you are getting, it is because of common mode current on the feedline. This is definitely due to insufficient Common Mode Impedance of the 1:1 choke. The FT-240-43 is OK but you need 17 or 18 turns of coax on it to obtain sufficient Cm Md Impedance.

[@barryinn1778]

Tim, great information. I would suggest some diagrams or drawings showing the different antenna's you talk about. I have a off center fed inverted vee wire antenna 22ft / 44ft 4;1 balun and I am having great signals rec/trans. on it. I am getting 6m, 10m, 20m, and 40m. SWR"S are 1.1 accept 40m which is 1.5 and I use the tuner to bring that down to 1.1. So all are 1.1 working great. The balun is at 31 ft and the ends of the antenna wire is 12ft from the ground. I am using Messi and paloni ultra flex 7mm copper coax and Davis RF flex weave copper wire.

[@timg5tm941]

Good points - thanks

[@ianxfs]

My 40m-6m OCFD was my first antenna and is still going strong and is the station’s main antenna. I have a choke to stop CMC, but other than that, no problems or faff. My reason for choosing was both the multi-band, plus the stealth nature of the design. With the short leg terminating at the roof ridge tiles, the coax drops neatly down close to the rear of the house and not halfway down the garden like with say a dipole. Worth a try Tim 😁👍🏻

[@TheNoCodeTech]

I've been using an OCF dipole for about a year, lots of problems with common mode. Never heard anyone mention the relationship between OCF dipoles and common mode. Thanks for the information.

[@VE9ASN]

A simple common mode choke will easily solve your issues.

[@timmack2415]

I have an OCFD up for about 15 years. It's 90 x 180 and is great for 160 M. I have a 6:1 current balun and, although a compromise antenna, it sure is convenient

[@tekspeditionplanet9109]

I need the lower bands for MARS work (and amateur) in the US and started with a G5RV antenna when I joined MARS. OK, with an external tuner I could load up the lower bands, but it really was only resonant on 20 meters and it felt like everywhere else needed an external antenna tuner to use brute force to get a match. SWR was not good on most of the bands. I then swapped the G5RV for a ZS6BKW, basically a modified G5RV, to get a few more resonant or close to resonant bands. It worked better than the G5RV, but still needed a lot of matching with an external tuner. I then swapped out the ZS6BKW for a Palomar 80-10 off center fed dipole. Although it too required some tuning, I found that the SWR was low enough on almost all amateur bands that I could tune with the internal tuner of my IC-7300. The one exception was 17 meters. The radio's internal tuner wouldn't even try to tune 17 meters. (Internal tuners normally can tune a 3:1 SWR mismatch; external tuners usually can tune a 10:1 mismatch.) Since I work MARS operations and I need to tune outside the amateur frequencies, I do use an external tuner anyway, so in the end I can pretty much tune the entire HF spectrum, including 6 meters. Not saying the OCF dipole is the greatest HF antenna ever made, but from my experience I believe it to be much better than either the G5RV or the ZS6BKW antennas. Most SWR plots for the HF band show the OCFD to be much flatter, with SWR low enough to be tuned with an internal tuner at most frequencies.

[@alanjames4526]

Hi, Tim. I am using two OCF dipoles at 90 degrees in azimuth to each other for 80, 40, 30 & 20 meters even though they go on down to 10 meters. Alan KZ6B

[@roydavis6110]

I have just now found your channel. I have been using an OCFD for 80 thru 6 meters. It is 45/90 feet, with a 4:1 balun. I have operated portable with it. Sure it is a bit much portable but it works so well for me and my applications. My antenna will also tune on 160 meters. I have mounted one on the conning tower of the U.S.S. Drum, a dry-docked WWII submarine. From Mobile, Alabama we have contacted hams from deep into the Carribean Sea to Canada and most U.S. States using only 100w SSB. If you have the room to hang it as an inverted V with the apex at about 50 feet, I find it performs the best. I will continue to watch your channel and hope to learn more about this great hobby. K5RMD

[@timg5tm941]

Sounds like it works well for you Roy 👍👍

[@radioworks]

YES, in double windom version it is the best multiband antenna for all bands ever. I've built and tested many many other wire antennas, but if I need just one single antenna for ALL bands, the double windom is the winner. With this antenna I did over 250 countries and DXCC on 9 bands with only 100W, within last ten years. I use other antennas too, but the windom is always the main one. The cost of this antenna is very low, if you build it by yourself. All you need is properly built balun and lots of wire. Of course, a good height is always crucial. If anyone interested in my particular setup, a pic and dimensions are on my qrz page. 73, Jan

[@timg5tm941]

Good points 👍

[@Rickm505]

OCF 40 meter dipoles will do well on 15 meters if you move the feed point and add a high voltage capacitor inserted in the long leg

[@albertmorris4889]

Hi Tim. I just came upon and watched this video. My personal experiences with wire antennas over the last 52 years range from individual dipoles for each band (80 & 40) some inverted v some "flat top" dipoles, some "mangled leg" dipoles to fit the space, to fawn dipoles, G5RV. All have in my thoughts performed well (in that I could work any station I could hear with power levels of 5 to 100 watts output). Except for the G5RV none needed a tuner (which is good as until the G5RV I never had one anyway). Currently I have a 40 only dipole up along with a 20/15/10 beam and a 5 band (20M & up) ground plane. I do have an OCF 80 - 10 & a 160 - 40 coil loaded short dipole built but my physical mobility limitations have kept me from getting them deployed as yet. 73 Al

[@timg5tm941]

Some great observations there Al. Thank you for replying. 73

[@ianbardell8030]

I have a 80m ocf dipole fed with coax 1/3 along with a 6:1 balun at 10m in height. 80m swr is a bit high over 3, however in 40,20 and 15m the swr is no higher than 1.7:1 and I've worked west coast USA to New Zealand on it. The antenna is bent in an V configuration 10m up

[@radioworks]

Add parallel wires and make it Double Windom antenna. You'll get a great performer for 9 bands at one. I am working the whole world daily with just 100W. Check my qrz page. 73, Jan

[@chrisbartlett6022]

Nice Video as always Tim. I use a 80 to 10 Windom, mainly because the Feed Point suits me. I also have a DX C, Cobwebb and 40 (ish) Meter Long wire . Initially for Years I only had the Windom. It suits me because of the feed point and seems to work well enough, however it is nice to have 4 HF Antennas up and be able to switch between them. There is no such thing as a best Antenna but having choices is fun :-)

[@grahamkent2868]

Hi Tim, great video, I use an OFCD on 40, 20 and 10 without any problems but I do change antennae often and thats part of the fun!

[@owlcricker-k7ulm]

I really like the OCFDipole because it is easy to build, resonant on most bands and requires little tuning at most, it is quiet and band agile. A sky loop is perhaps a better option in a permanent setting, but for portable not so good. I have built them from full legal limit down to QRP and all are work horses.

[@timg5tm941]

Plenty agree with you - like all things in this hobby its a personal preference thing. Some prefer OCFD and others EFHW etc.

[@owlcricker-k7ulm]

@@timg5tm941 Tim, I use both regularly and each have pros and cons. EFHW is easy to put up and support. Several setup configurations add great flexibility. But it s more limiting on bands. I have started putting links in for 17m and 30m. The OCFDIPOLE requires a little more to set up and support. Flat top and Inv V is about it, but complete band coverage is wonderful. Do you need quick and simple or broad coverage. Building and using antennas is way too fun not to have as many as possible. Seems like you have a blast testing them all out. Super channel, keep up the good work. Anything that radiates RF is fun.

[@leftturnaudio5678]

40m inverted v at 35 ft and legs at 45 degrees works great for me and gives me solid performance during the day for rag chewing out to about 500 miles in all directions.

[@timg5tm941]

Yep - does the job

[@gregpollard844]

Agreed, too complicated. I've been using efhw on 40m. I have the feed point at 30 feet with a ground wire straight down to a rod. The 66ft wire goes out horizontally to another mast 51 ft away the straight down for the last 15 feet. I'm in Ohio and my farthest contact has been Namibia V51WH on 40m, but Europe is no problem with it. Getting ready to it on holiday to Florida so when I get home I try an inverted L for 80m and see what other bands it will work also? Greg W8XP

[@M0RMY]

DXC, 80m (254ft) loop with 4:1 and a hexbeam if room enough. The three antennas I'd recommend for any station before a tuner. Only one option? 40m loop if space, DXC Classic if not.

[@johnkershaw9575]

Hi Tim. Great video, as always. I've been using an OCFD for the past two years and love it. In that time I have made official contacts with 83 countries, mostly FT-8, but still fun. On SSB I can talk throughout the US when the band condition are right. When the sun goes down 80 meters is a clear as a cell phone. I consistently work 30, 20, 17, and 15 meters during the day with an external tuner. All on 100 watts. Push up masts are the way to go. I use 25lb monofilament fishing line to be as stealthily as possible to guy it in my yard. Take care. John N6NRO

[@radioworks]

I did WAZ, WAS, 9BDXCC and over 250 countries with OCFD (80/160/ - 10m "double windom" version) with just 100W. I work the whole world daily, of course, if condx allow. 73 Jan

[@WaynePatrick]

Hey Tim, I enjoy your videos. I have been using a 80-6 meter OCFD for 10 or so years. It is a good choice but common mode is a problem even with a 1:1 balun.

[@timg5tm941]

I hear it often is with an OCFD

[@Joe-KN4IFI]

I have never tried an off center fed dipole. I uses a home brew 66' EFHW that gives me 40m, 20m, 15m and 10m "I uses a tuner to bring in the WARC bands". I uses a Mono Band Inverted Vee for 30m and a base loaded Vertical for 10m. I have made a coil based on a Mike M0MSN design "God help me!" to attach to my End Feed to see if I can tune in 80m. I love my EFHW. I make it into Europe on 40m I even had the honor to have a QSO with the legendary Callum of DX Commander fame :). Like you, I have a small backyard. I also live in a deed restricted community so no fancy towers and such. Great video Tim. 73 Joe

[@MikeN2MAK]

Just rewatched because I might be up to something. Thanks for the evergreen content.

[@timg5tm941]

Thanks Mike!

[@andygee7017]

Does an inverted V have less ohms because some of them have rolled down and fallen out of the bottom?

[@DavidProctor-i7x]

Hi Tim great videos. I’m using a double bazooka antenna. Easy to build easy to tune and works great. Regards Dave .. M0IOK.

[@timg5tm941]

Nice one!

[@BarefootBeekeeper]

How about an off-centre fed linear loaded doublet?

[@timg5tm941]

My interest is suddenly heightened 🤔

[@owlcricker-k7ulm]

Tim, great information on antennas. I send links to many new hams so I don't have to talk so much. I use a wide varriety of antennas and the OCFDIPOLE is a favorite for band flexibility. I use both 80m and 40m versions. End fed randoms and EFHWs are favorite easily to deploy antennas. The EFHW just doesn't give the multitude of bands that the 80m OCFDIPOLE gives me at 12m high. I carry all these and more when I am portable and for rapid deployment the random then the EFHW are first to go up. All good. VK2PRC has a great 2 band DX vertical, 20m EFHW, 40m ¼ wave, on KZbin that is a real favorite of mine. Very similar to your vertical but he has a feed change to get a 40m ¼wave. After your video, I am thinking his may be a 4 band. I will check.

[@timg5tm941]

Thanks for the great info!

[@jameyevans29]

Mine wouldn’t tune until I put a common mode choke before the radio. Now I don’t need a external tuner and get 160 through 10. I haven’t tried anything else but I do have a ZX6BKW, I don’t have the means to get it up at the recommended height. Make sure you get a choke on your coax. 73!

[@jameyevans29]

*ZS6BKW antenna

[@timg5tm941]

Great points, thank you! 73

[@jameyevans29]

@@timg5tm941 Thank you for the video!

[@TheRudydog1]

Hello Tim from the Pacific North West, USA. I've been using an 80-10M ocf dipole up 100 feet for the past 2 years. Bottom line: It gives me most HF bands with about average performance for a dipole configuration. Quite good stateside coverage and fair dx performance so I cannot say I am really satisfied with the ocf dipole. I'm in the process of installing a horizontal loop that is 2 wavelengths (1150 feet) on 160 fed with 450 ohm ladder line. All four legs will be 90 to 100 feet high taking advantage of the tall Douglas fir trees here in the PNW. I will be leaving the ocf dipole up and do comparisons with the loop. I will share my results with you and perhaps even post them here on KZbin. 73 OM

[@timg5tm941]

That would be great to see - 73

[@stevegordon2869]

I use 80m ocfdipole with 4:1 balun also 240-31 core below balun and one in shack 10 turns of coax through each. Very good antenna one side is 89 ft and other is 44.5 ft.does need tuner on some bands works fine on 15 meter with tuner coax to it is 100ft of rg8x may make s w r look better than is.also have g5rv use both some days one is better than other.73s.

[@Aswaguespack]

Good info Tim. Here’s what I have found on OCF Dipoles and here’s a summary: The following is related to a 80m OCF dipole (~135 feet total length): * If you feed it at 8.9%, you don't lose any ham band (80m-6m)(no in Ham band sine nulls). Although the SWR will be higher on 80m. * If you feed it at 16.6%, you lose 15m band (sine equals zero). * If you feed it at 20% (20/80), you lose 17m and 6m bands (sine equals zero). * If you feed it at 25%, you lose 20m and 10m bands (sine equals zero). * If you feed it at 28.89%, you lose 12m band (sine equals zero). * If you feed it at 30%, you don't lose any ham band (80m-6m). Although the SWR will be a little higher on 12m. * If you feed it at 33% (1/3:2/3) you lose 30m, 15m, and 6m bands (sine equals zero). * If you feed it at 36%, you don't lose any ham band (80m-6m). Although the SWR will be a little higher on 30m. * If you feed it at 41.6%, you don't lose any ham band (80m-6m). Although the SWR will be a little higher on 17m and 12m. * If you feed it at 50%, lose 40m, 20m, 15m, and 10m bands (sine equals zero), but should do very well on 80m, 30m, 17m, 12m, and 6m bands. This is a normal dipole, where you only get odd-harmonics. By "lose," I mean the antenna will not be useable and will have very high SWR.

[@timg5tm941]

They are unusual beasts aren’t they? I’ve recently used a standard 1/3:2/3 fed version and had a ball working close distance contacts around europe on 40m as a portable station. Thanks for stopping by!

[@donaldshields2483]

Thank you for the video I have two I sent offense I have an engine media and I have a funny later thanks I just put the fighting meter up today and I haven’t even tried it yet I don’t like downtown as I work anything I wanna work I’m not I’m not gonna do the exit so I don’t care if I don’t work in a red DX but I enjoyed listening to your video and everybody has their own opinion so I’ve been listening God bless

[@timg5tm941]

Thank you !

[@slappomatthew]

I was running a fan dipole for a while just switched to an ocfd not sure about it. Swr isn’t great. 2.75 on most bands

[@chrisg7veo495]

Interesting video thanks Tim. I use a G5RV as more convenient for me spacewise to feed in the middle. I am missing your diagrams while talking! maybe a blackboard in the shack?

[@radioworks]

G5RV is good antenna, but if you make modification into ZS6BKW version, you will get much more from that antenna. Check my qrz page. 73 Jan

[@barbsblogs1563]

Hi Tim another helpful video thanks, I’m thinking of putting up an endfed wire iv made the 49-1 and that checks out ok on the vna , my problem is I cannot get up a 66ft wire so I was thinking 33ft and hoping that would give me 20 15 & 10, just wondering your thoughts on that and would it work ?

[@timg5tm941]

Ah now 33ft with a 49:1 won’t get you 15 only 20 and 10.

[@kellypaws]

Perhaps there are loads of people using the OCFD. They're just not getting out well!

[@mrdonkersley]

Using a doublet with 2 X 20.5 metre legs. Wouldn't mind trying an OCF as I have a spare 4:1 balun. It would have to slope down from the house so would I put the shorter leg at the top or the bottom?

[@StuartM0TTQAmateurRadio]

There's no performance difference between a dipole, EFHW or OCFD, it is really a question of mechanical convenience. What match you get with on OCFD on bands other than the fundamental is going to be pot luck, including perhaps some feeder excitation and other unexpected modes, but if it works, it works. The most "honest" variant is the Carolina Windom, which sell commercially for insane sums and the manufacturers cite the feeder radiation as a predicted mode of operation.

[@sbateson67]

Good to work you Tim the other week on my Hyendfed 40/20/15/10 antenna ,with a CMC on it also.

[@timg5tm941]

Thanks Simon - me too 73

[@donaldshields2483]

Nice video should I listen to it I have two in fence I’m sorry I had an infrared.

[@VE9ASN]

Recently read a comment about challenging the traditional 1/3-2/3 feedpoint with a much closer to center 40-43%, this would reliably give 15m and in theory should be less common mode? What say you? 73.

[@timg5tm941]

I would have to check that out

[@martindrury9740]

Interesting video again Tim. I was going to get a OCFD but think i will hold back. I was thinking of adding traps to my 40M inverted V to bring in 20M. I was wondering if I could also add wires for 10M too. 73.

[@radioworks]

You can add wires for any band in parallel and make it Fan Dipole. I have one fan dipole with 4 parallel wires as inv.vee for 80, 40, 20, and 10m. 1:1 balun at the top. I have also another Fan Dipole for warc bands. Works fine. But I you want to have just one antenna for ALL bands, build the double windom. 73 Jan

[@evertwenderpirt6328]

Look at the hitch hiker's guide to the off centre fed dipole . . .

[@Andy2e0ree]

I us a trap inverted L trap for 40m= 80m and a bit on the end for 160m

[@ReedAB8AS]

Another good video Tim. I prefer the EFHW for sure. Thanks and B SAFE de AB8AS

[@donaldshields2483]

I have a eight

[@marklowe7431]

I'm not expert on any of this but one thing which seems to come up in my study is that performance results are varied by surroundings. The same antenna in different places may have significantly different results. Could this be why some love them and others had disappointing results?

[@timg5tm941]

Very possibly Mark you raise a very good point here

[@2e0ggjrobin31]

Thanks Tim Half size G5RV here

[@dangermandave67]

Gosh. Might as well just use a 40m EFHW.

[@markcartlidge7107]

Hi, I’m new to the game so all advice more than welcome. I got a yaesu ft450d hf radio and I’m using the spider beam antenna Ariel 51 model 404. I’m an M7 so I’m restricted to 10W and It seems to get around Europe ok But no farther, I here how people get to USA on 10W and I’m thinking is my set up not cutting the mustard or Do I need more power. I’m studying for my intermediate license so hopefully one maybe I’ll be in 50W In the near future 🙏🤞.

[@timg5tm941]

Hi Mark - try my 20m half wave made out of coax or the 10/11m version - they work great. Good luck 73

[@radioworks]

I can recommed 3 antennas. All of then you can build for juat few bucks. Double Windom, ZS6BKW and Cobweb. But always, the height of the antenna is crucial. In other words, anything bellow 10m agl is bad. Also, it always depends on actual condx. So with good antenna height, the 10W is enough for DX, especially on FT8.

[@DavidVanDensen]

He is very uneducated in the feed points used in an OCFD. The OCFD is one of the most powerful antennas you can use. Just a little work to tame the CMC, and away you go.

[@timg5tm941]

Ah ok 73

[@stevecrawford3551]

Thanks for sharing… you need a chalk board to explain it. Thanks. 😀

[@timg5tm941]

Thanks for the idea!

[@prestonshute7243]

40/80 bazooka here. Love, I get all of 40 and my Ic-7300 gets a good part of 80 Had a OCF dipole, never got all the bands they claimed. 73 wd4dda

[@nickothen9492]

Nooooooooo looking at that in the garden would drive my OCD crazy

[@markg6jvy135]

👍👏👏

[@siffler1234]

hi tim, i was always under the impression the answer was in the ratio of the balun ie: 4:1, to make the equation simplified ..for a 10m full wave 4:1 ocfd 10m divided by 5 =positive/hot/live/antenna =8 meters ..and negative/ground/counterpoise =2 meters?? regards your friend joe m1dls 👍👍

[@brian.7966]

ah there you are, thought you had gone missing lol :)

[@johnnorth9355]

Very interesting but slightly irrelevant until I get a transceiver - my UV5R does not warrant such sophistication lol. 73

[@G7VFY]

Cough cough double bazooka...cough cough...

[@Brenda-jf2pe]

Marvelous to hear how people in the UK have taken to Ham Radio these days! I think the COVID prison has peaked their interest. Anyway, Balun Designs here in the US has some really high quality hand made Balun ‘s for OCFDP antennas! Thanks for your video, I enjoy the Elmering 🇺🇸😎📡🎙JohnBoyUtah KJ7TBR. Chow

[@timg5tm941]

Ah nice one!