Dipole Vs EndFed - Field Measurements

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Күн бұрын

Пікірлер: 55

@StreakyP Ай бұрын

This is a beautifully thought out & conducted trial. Respect. Just some thoughts:-the efhw has the advantage of working on even & odd harmonics but the dipole cannot handle even harmonic operation however balanced antennas like the dipole can suffer less from local electric noise pick-up compared to unbal antennas like efhw & verticals. It looked like your test site was well away from local noise sources so here given its equal performance to the dipole but advantage of even harmonic operation for the efhw I'd probably choose the efhw, but in an urban environment for the home station I'd possibly choose the dipole instead IF it was quieter. The fact you were measuring snr was nice to see. It would be interesting to see the same trial conducted in a noisy urban environment to see if the theoretically quieter operation of balanced antennas gave the dipole any advantage there.

@CrazyChekov Ай бұрын

thx for the comment! Great points!

@tdcowder Ай бұрын

Thanks for your work. I really appreciate the information. I spend a lot of time deciding between end fed and dipole and end fed is much easier at my house.

@CrazyChekov Ай бұрын

You're welcome and thank you!

@75ohmHAM Ай бұрын

Great video, look Forward to more!! 75's 😎

@CrazyChekov Ай бұрын

thank you!

@DaDitDa Ай бұрын

Proof that a dipole is a dipole, regardless of how it's fed...

@rogerlafrance6355 Ай бұрын

Yes, but used as a multiband antenna, multi lobes increase with higher bands. Trading some performance for multiband works in most cases. It seems to me that performance drops above two bands. Upgrades include Traps and Relays to switch wires

@kenmartin1211 Ай бұрын

Nice test ! Thank You

@msf60khz Ай бұрын

Thank you for your measurements. At higher harmonic frequencies, the end fed inverted vee is a useful directional antenna.

@CrazyChekov Ай бұрын

You're welcome! Yes that could be useful. At some point I will compare that with a vertical I guess.

@AJFogertyFan2 21 күн бұрын

@@msf60khz I agree for horizontial antennas . However, end fed VERTICAL antennas tend to lose low angle lobes desirable for good DX performance to multiple high angle lobes at higher harmonic frequencies. Case in point, I run a nominal 33 foot 20 meter end fed half wave inverted L which is a very good long haul DX performer. However, as an end fed full wave on meters, it’s performance is always at least 2 S units (12 dB) down relative to a reference dipole, based on real time antenna A/ antenna B reports from DX stations, also very evident in received signal strengths at my end of a QSO. AJ1G

@AJFogertyFan2 21 күн бұрын

End fed full wave vertical dipole on 10 meters is way down relative to horizontal dipole on 10 meters. A really GREAT high order harmonic dipole, either end fed or more common center fed is a 75 meter half wave dipole with a fundamental frequency at around 3850 kHz operating as a 7/2 wave on 10 meters. Stumbled across this gem when randomly exercising my IC7300 auto tuner to see if it could any matches besides the obvious one. To my surprise, the 75 meter went into tune with a perfect match almost immediately on ten meters. An SWR band sweep plot check with the 7300 internal tuner off showed a not too awful slightly less than 2:1 across the band. Did some googling on 10 meter 7/2 wave doublet dipole and came up with a QST antenna project article on the exact subject, and also some modeling results. At 10 meters a nominal 3850 kHz fundamental dipole exhibits a nominal feedpoint impedance in the vicinity of 100-200 ohms, well within the matchable range of the IC-7300. The old QST article presented an elegantly simple technique to allow a near perfect match on both 75 and 10 meters by adding a 10 meter quarter wave impedance matching section of 75 ohm coax in series between a 50 ohm feed line and the antenna feed point. The length of the matching section, which needs to take into account the 75 ohm matching section coax velocity factor worked out in my case to be 7 feet 10 inches. This brought in near perfect 1:1 match over the entire 10 meter band. It’s essentially transparent with respect to the match on 75 meters and is left permanently in line at the feed point. Modeling of a 7/2 wave dipole shows very useful 8 dBd (that’s dipole not isotopic dBi !) in 4 directions nominally 30 degrees off the antenna axis. For my east-west dipole that’s to NE (Europe), SE (Japan long path), SW (lots of USA and ZL) and NW Alaska and Japan short path). Helped me run up a respectable score and qualify 2nd place single op low power CT section in the 2023 ARRL CW DX Contest using only wire antennas and a relatively short 17.1 hour on air effort. 10 meters was my best scoring band in the contest.

@AJFogertyFan2 21 күн бұрын

@chrissuddell7940 Ай бұрын

Well done.

@CrazyChekov Ай бұрын

@@chrissuddell7940 thank you!

@hennero.3826 Ай бұрын

Thanks for sharing this! 🙂 This is exactly the information that I am interested in most as I am forced to operate outdoors when I really want to do interesting DX (due to my living situation), so I am looking for the most efficient wire antenna for outdoor operation. By the way as of now with being into the hobby a few months only, I am trying to go for verical wire antennas which is feasible as I am using most 15/17/20 m. And as you mentioned - I would have expected the advantage of the dipole to be a bit more obvious. 73 de DL1HNR

@CrazyChekov Ай бұрын

thx a lot! Yes for DX and 15-20m I would also chose a vertical antenna. 73!

@hennero.3826 Ай бұрын

@@CrazyChekov Until now, I was not really sure if this approach makes sense as it is merely what I as a newbie understood so far from radiation patterns and everything that goes with it, so it is good to see that you confirm my conclusion to go for a vertical for that purpose! This help me, thank you.🙂

@RoelandJansen Ай бұрын

@@CrazyChekovI did, actually

@petersichel9934 Ай бұрын

What I hope viewers might take from this is that a well designed and properly deployed EFHW can provide good performance similar to a dipole with some obvious benefits for certain use cases. These benefits include simpler deployment options when portable, and multi-band operation. Deploying as a vertical is great for DX, especially if you are by salt water. Using a very efficient 49:1 transformer as shown reduces losses to about 0.5 dB (compared to 1.5 dB for some entry level builds). Don’t be afraid to consider an EFHW, OCFD (Off Center Fed Dipole), or even a RW (random wire) for multi-band operation. The benefit of being on the right band at the right time is well worth the compromise involved.

@CrazyChekov Ай бұрын

well said, thx a lot!

@AJFogertyFan2 22 күн бұрын

Two other ways to compare the performance of two a antennas: Use the Reverse Beacon Network on CW CQ transmissions. Or - Monitor your signal amplitudes on remote on line Kiwi SDRs while making CW test transmissions using long dashes. If using the Reverse Beacon Network to compare two different antennas closely in time you will have to transmit on slightly different frequencies for each measurement as the network only updates once every ten minutes for a given station on a given frequency. You can also get a sense of how well your station is performing relative to any other stations being detected at a given station at a given time. With the Kiwi SDRs you can watch your signal levels in real time in the spectral amplitude display while repeatedly switching back and forth between two different antennas. And you of course can also hear and see how your station’s signal is being received compared to any other stations being received by the SDR in real time. AJ1G Stonington CT

@CrazyChekov 21 күн бұрын

@@AJFogertyFan2 thx for your comment and info! Good ideas!

@AJFogertyFan2 21 күн бұрын

Some people like to use PSK Reporter for doing what I recommend with the Reverse Beacon Network. In my experience, at least for CW mode detections, RBN blows PSK away with the number of nodes on line at any given time, also the RBN list format of the results is much more straightforward and easier to read. RBN also has a very good ray trace map display that shows all the nodes detecting a given transmission over a given time window. The results time window filtering can be as short as the last number of minutes to up to 10 YEARS! Many other data filtering options are also available with respect to locations of detecting nodes such as by continent or country, and direct comparison of specific transmitting stations, wild card things like AJ1G*, which will shown results for AJ1G and AJ1G/M, which I often do when comparing my mobile’s antennas to my full sized home station antennas. Would like to see the KZbin antenna posters show some quantitative results from the RBN vice the usual sound bites of QSOs! It’s great to test out a new antenna setup and see a ray trace bloom to a all over North America, Europe, South America, the Caribbean, and the Pacific all at once, and a page full of mostly double digit SNRs from a minute or two of CQing! I routinely have RBN up in real time whenever I’m on the air on CW, even when there aren’t many live ops on a band you can at least see how the.RBN nodes are detecting you and others. AJ1G Stonington CT

@CrazyChekov 19 күн бұрын

@@AJFogertyFan2 awesome thx for the infos. maybe will use RBN for some stuff in the future. only receiving you cant test with that method if Im not mistaken.

@AJFogertyFan2 19 күн бұрын

@ You can run testing on RBN. Just send a string of TEST DE CALLSIGN a few times. But don’t do that if there is a contest in progress on the band. There’s a lot of info on how to use RBN on the RBN home page.

@wojteksz.8984 Ай бұрын

This video does not state whether a dipole or EFHW is better; instead, it shows which of the antennas in the author's specific setup and configuration provides a stronger signal. It cannot be said that the measurement is wrong, but it certainly does not answer the question: "Dipole or EFHW - which is better?" We could try addressing the following questions first: Was the layout of the coaxial cable considered, and its interaction with one of the antenna's arms, where it might run parallel? Was the efficiency of the 1:49 transformer considered, and were the dB losses subtracted from the result? (What would the result be if the EFHW were powered in parallel through an LC resonance circuit? Resonance circuits have very high efficiency but make the antenna single-band or require retuning.) Did the author consider that when using a dipole, the EFHW antenna has no break in the center and acts as a half-wave element that could behave like a parasitic element? What constituted the counterpoise for the EFHW, and how was it implemented? (Coaxial cable, grounding, or a wire segment?) Was it taken into account that the effectiveness of the choke depends on where it is installed along the coaxial cable? The impedance for common-mode currents changes along the coaxial cable. These are just a few example questions. As we can see, the video does not conclude whether the dipole, as a dipole, is better than the EFHW, as an EFHW. The video only shows that the author's dipole is better in his setup, considering the antenna suspension configuration and the coaxial cable layout. Nevertheless, it is worth noting the remarkable measurement method, where our own station automatically responds and provides a report. Choosing the frequency 7078 kHz was a good decision, as it avoided distortions in the reception report in dB caused by interference from other stations.

@CrazyChekov Ай бұрын

thx for the detailed comment. especially the coax coming down the pole from the dipole bothered me a bit too. it wasnt really parallel but for sure that could be improved for future tests. good points!

@stewartrv Ай бұрын

@@CrazyChekov I'd suggest maybe to be even more accurate you could do half of your tests and then move both antenna's 90 degrees and do again. Then you can cancel any potential noised picked up from a specific direction. And I also thought that coax really needed to go straight down the pole and then across the ground. In any case it was still instructive, good job!

@CrazyChekov Ай бұрын

@@stewartrv I agree that would be even more accurate. Thx for the ideas!

@HowardKlein1958 Ай бұрын

I've found end fed half wave works very well, especially low to ground NVIS propagation.

@CrazyChekov Ай бұрын

@@HowardKlein1958 Yes, I thought the difference to a center fed dipole would be bigger. these transformers seem to work very well.

@stewartrv Ай бұрын

@@CrazyChekov I'm curious did you build the 49:1 following Colin MM0OPX experiments?

@CrazyChekov Ай бұрын

@@stewartrv yes he did awesome work on measuring them.

@skypilot0077 Ай бұрын

An end fed is a dipole. It's just fed at the end instead of the center. Deployed as a flat top, sloper or inverted V they should perform the same.

@chrisolson968 Ай бұрын

Skypilot, you are flying too high. A dipole is the best antenna in a inverted v fashion. In an efhw. The matching transformer does the heavy lifting to make the antenna radiate efficiently. With a dipole although a mono banded antenna, is the most efficient. However, this gentleman made a great matching transformer, due to the efhw performance. I am impressed with the results. However you cannot beat a balanced dipole. You just cant. Yes they are both wire antennas. A dipole is a dipole. An end fed is an end fed.

@skypilot0077 Ай бұрын

@@chrisolson968 An EFHW is nothing more than an end fed dipole. It's a half wave piece of wire that is resonant on a certain frequency, just like a dipole. OCF antennas are dipoles and typically use a 1:4 impedance transformer so it plays well with a 50 ohm coax. The EFHW is no different, it just fed at the end instead of slightly off center and uses a higher ratio impedance transformer so it plays well with coax. You could call it an extreme off center dipole if you wish but it's still a dipole no matter where you feed it. Do you not use the same formula for calculating the length of the wire? Think about it.

@chrisolson968 Ай бұрын

Once again, look up the definition of dipole. Two equal lengths. So lets just call any wire antenna a dipole. A loop, rhombic, Marconi, etc. Efhw sometimes are not used with counterpoises. Ones with counterpoises don't have much of a counterpoise. Dipole is a classification. Yes an off center fed, is referred to as a dipole of unequal lengths with a matching transformer. Hey can you make a cage efhw? If you remove the matching transformer from a efhw, what do you have then? I guess antenna handbooks for 100 years have had it all wrong. Glad you have cleared it up. Thanks

@vladtepes481 Ай бұрын

While your experiment is rather good but there are flaws. The radiation pattern of an end-fed and center fed dipole are identical for a fixed antenna height. The chief difference will be the efficiency of the 49:1 UNUN. A center fed dipole is rather efficient. Your antennas are placed 90 degrees with respect to each other so the signal received at a distant point be different. Antenna modeling can be used to determine the effect of antenna orientation. You only need to model a centerfed dipole as the radiation pattern is unaffected by the feed point location. You just need to know the difference in gain for a change of 90 degrees. A low inverted V will not have much directionality but modeling is easy using EZNEC or MMANA-gal.

@CrazyChekov Ай бұрын

thx for the comment. I wouldnt call it an experiment. Its was just a test. I like to test stuff more in the real world than modeling it. The direction of the targeted station was between the dipole and the endfed. 45deg to each of them.

@wd8dsb Ай бұрын

Modeling using 4NEC2 shows almost an identical pattern and gain between a center fed dipole and a EFHW operated on its fundamental band when both are mounted horizontally when using the first 0.05 wavelength of feedline as the counterpoise with the EFHW and measuring RF current at the center of both antennas agreed almost perfectly with what modeling predicted. Only real difference is transformer loss with the EFHW but my homebrew transformers have a measured efficiency of 90% which equates to a loss of only 0.46 dB which is less than a tenth of an S unit assuming an S unit is 6 dB.

@M7XCB Ай бұрын

Very interesting video.

@wojteksz.8984 Ай бұрын

It is unclear whether the statement "WINNER" refers to the dipole relative to the EFHW or to the dipole with a choke versus without a choke when using a voltage balun. The statement "WINNER" about the dipole, where the assumption from the video title suggests it is in comparison to the EFHW, could be misleading for new radio amateurs. Even though a more accurate phrase like "MY DIPOLE IS THE WINNER" would be appropriate, the use of "WINNER" is somewhat inadequate. Nonetheless, I give a thumb up 👍for the effort, as it provides inspiration for others. 73, Joe

@user-yh7mv7jd1l Ай бұрын

Thank you. I appreciate the methodology and the data. It’s very illustrative. KO6DEV

@CrazyChekov Ай бұрын

@@user-yh7mv7jd1l thank you!

@P.SeanCoady Ай бұрын

I am surprised as well

@wd8dsb Ай бұрын

Results are pretty much what I would expect when using a EFHW on its fundamental band versus a dipole for that same band. Modeling using 4NEC2 shows almost an identical pattern and gain between a center fed dipole and a EFHW both mounted horizontally when using the first 0.05 wavelength of feedline as the counterpoise with the EFHW and measuring RF current at the center of both antennas agreed almost perfectly with what modeling predicted. Only real difference is transformer loss with the EFHW but my homebrew transformers have a measured efficiency of 90% which equates to a loss of only 0.46 dB which is less than a tenth of an S unit assuming an S unit is 6 dB.

@mrlowbudget6979 Ай бұрын

Oha wiener Dialekt in Englisch ist aber schwierig :-)

@CrazyChekov Ай бұрын

ha ja da hast recht 😊

@huangcheng2130 Ай бұрын

The directivity of end-fed antenna is very strong, so it is meaningless to pay attention to directivity when comparing horizontal antennas.

@sfrahm1 Ай бұрын

"The directivity of end-fed antenna is very strong" In what direction? How is it different from a dipole arranged in the very same configuration? My understanding is that it is nearly exactly the same. It is the shape and placement that primarily determine directional or elevation characteristics. If the current node(s) is/are at a significant height relative to wavelength, the angle of radiation will be low and visa versa for low heights and NVIS radiation.

@CrazyChekov Ай бұрын

better to have it equal for both antennas in a comparison imo. removing one variable from the test.

@gunterkonig959 Ай бұрын

You are right, because the efhw antenna field pattern is for a small part directed in the opposit to the feed point.

@wd8dsb Ай бұрын

Gain and pattern of an EFHW operated on its fundamental band is almost identical to a dipole when both are mounted horizontally and using the first 0.05 wavelength of feedline as the counterpoise with the EFHW. Biggest difference is loss in the EFHW transformer but my homebrew EFHW transformers have a loss of only 0.46 dB which is less than a tenth of an S unit assuming S units are 6dB. For all practical purposes they perform the same on their fundamental band assuming the EFHW transformer is efficient and assuming you use a counterpoise as mentioned above.