Ham Radio - A 75/80 meter single band fan dipole

DX Engineering sells window line by the foot. It's a nice product, and has stood up well at my shack. Looking forward to seeing how this antenna works! 73 de w8tam

I'm torn between thinking this should work and thinking that if it worked it would be in common use already, but I'm not at all conflicted in my desire to see the results of this great experiment. Thanks for bringing us along.

End supports from the first solid piece between the longer and shorter conductor? Otherwise you will be supporting the antenna from the longer antenna only, which may cause mechanical problems.

K....you are an antenna.
Knowledge reception. ⚔️🇺🇸⚔️

Great idea .. my antenna was also made out of 450 ohm ... thing I noticed was the additional wind load compared with single wire and this caused fibre glass pole to collapse a few times. Good luck with the experiment 73

Sounds interesting! :D

I've used a fan dipole for many years. Mine is made with 300ohm twin lead and fed with 60' of RG8 and only center and end supports. Works great however I only use 200 watts at most. I also made a 5 band fan dipole using 5 conductor rotor cable. Works very well just don't push a lot of power through it. Your idea should work great but remember, the impedance changes as the height above ground is changed. Put the feed point as high as you can get it. 1/4 wave on the 80 meter band would be ideal. Good luck and enjoy....

Look at QST magazine March 2013.
Inductive element.

MMANA comes with the 80_75dipol.maa file. Not window line, but 90 degree on the elements.
326 khz wide SWR < 2 There is also a 80_75dipolpar.maa with wires further apart then you intend, but you could easily move those wires closer with a little edition.

Great idea Kevin. I built my 1st fan dipole around 10yrs ago. It was a 3 strand 4 band’r that worked very well, even tho i could only get it up to 28’ at that time. The bands were 40, 20, 15 & 10 meters. On the 40m legs i put a wire figure 8 for capacitance at the 15m points. However, the point that i have to make is, i had to seperate the 3 strands by at least 6” starting approx 6” from the feed point due to harmonix. That is where the best swr landed in my situation. Im am not sure how your experiment will turn out and looking forward to try it myself if you are successful. I really enjoy your videos on antenna experiments thats where a lot of my passion is.

You fired a synapse over here... I wonder if this would work for an 80M/40M NVIS quick deployment type dipole. What are the element spacing requirements using different bands?
Thanks for the video! I look forward to the follow-up!

I built a 20M/40M fan dipole and had it installed in an inverted-V about 30' at the center point. I had each dipole 90 deg to each other, and it worked really well. Love the videos! 73 K4STM

I'm on the edge of my seat waiting to see/hear the next installment of the antenna. Good advise for crossing a desert is, "go slow and drink plenty of water." Same applies here in SoTex. Humidity can be brutal, especially on the coast. Good luck, and waiting for results.

Is a fan dipole just for hf or is it doable on for instance 2meter and 70 cm?

Wireman

Its a brilliant idea....can also be done for 20/40m bands...

It might be interesting to do some measurements of returned power BEFORE you cut one side for a higher frequency. I'm wondering if a broader SWR curve could result from what is, in effect, a larger diameter radiator.

Yo Kevin!:
Great video! I considered also using 5 conductor rotor cable, might be cheaper than ladder line, but wonder if the element spacing comes into play(?) : ) Think it might be seen/ treat it as a single element. It would be interesting to put up a rotor cable fan dipole for comparison! What say?
de seeker/Jeff WA7LFP

Hi Kevin, yeah our club on field day does exactly that! It will work great!

Btw, if you get 2x100 foot rolls, you can cut them to make a fan dipole for 75/80 AND the cut off for a high/lo 40 meter too! You could even attach both 40 & 80 to explore a multi--FULL-band fan-dipole.

Fyi, back in the early 90's, I made a ALL band SWL multi-bander using 300 ohm twinlead. My shortwave signals came blasting in from where I mounted it inside the very long attic of my then apartment building...

73 John

I am thinking it will act a lot like a "Fat" dipole...

What would be the effect of using 75 ohm coax instead of 50 ohm?

Why not split the antenna only at the end?

-------------------------------------------------Feed -------------------------------------------------
----/ \-----

MMANA-GAL modeling software: $0.
Highly reactive test antenna: maybe $25?
Fun: Off the scale.
Experience: Priceless.
Go for it!

The Wireman also sells by the foot.

I like the idea of a fan dipole made from wide ladder line, but how close can you put the two dipole elements if you narrow ladder line or just use wire?

What happens if you connect the ends together of a multi-band dipole?

HI
Have you tried using the ful ladder line same length?
In the old days you might see large conductor dipoles, A ring with multiple wires for each side of the dipole. I remember seeing this layout on various pictured antennas, I think the idea was to electrically have a large conductor dipole to flatten the SWR curve.
Thanks

been running a 48 wire Fan dipole for 2 years here, using 3x sheathless Cat5 each side cut for 80, 40, and 20 with the Cat5 unraveled and trimmed to resonate across the bands. Its flat on 80,40, 20, 10,15 and 10 meters, needing very little persuasion from the ATU to work on 6, 17, 12, 11 and 60 meters. I think it acts like a Carolina Windom on those other bands. Feedline is 90 ohm twin feed. 73 de ZL3CJH

If you play with the angle of the dipole, you can achieve a 50Ω impedance, matching the coax line and transceiver. The issue is, in a portable situation, it is not alway easy to reproduce this angle, but, as you stated it, the cost of the mismatch is a 1.5:1 SWR, which is perfectly fine for any transceiver.

Brilliant idea!!

Both DX Engineering and GigaParts have 450 ohm ladder line. 130 feet is $98 at DX. They also have some LDG balun for $30.

Thanks for the video, Kevin. What you are describing is actually quite a common practice of making broadband dipoles. At least it's definitely described in the book "HF and VHF antennas" by DL2KQ (ex. EU1TT). Sadly it doesn't look like this book was translated to English. You can even make a dipole that covers 3.5-14 Mhz with low SWR if you wish. However the lowest SWR value in this case will rise to about 2 or maybe 3. Another problem with broadband antennas it that they are prone to pick the noise from all the sources that transmit on the bandwidth of the antenna. For these two reasons such extreme broadband antennas are not very practical except when you need a receiving antenna that covers all frequencies you are interested in. Interestingly, the discone antenna is in fact such a broadband GP turned upside down. 73 de R2AUK

I need help with my experiment antenna. Need of 2 64:1 autotransformer. For a RX station that can be used quick set up.

Kevin, can you please make a video on making a low band amp using the 5v bias t? It would be so helpful for me. Love your videos I will always watch them. 73 ke0wfy

I wish you luck! My attempts at an 80m/40m/20m fan dipole failed after I discovered that the bandwidth of any individual band of a fan dipole is narrower that that of a free standing dipole. That was found out experimentally first than confirmed on 4nec2. This meant I could only get about 60khz of bandwith on 80m and 100khz on 40m.

Before you drop $100 on ladder line, why not run a simulation and see if you get the SWR trace you expect.

Charlie KM4ZZ

Very good idea like to see if works look to make one with 2mm wire for 2 size ok 73 kiping touch to see how its gona work ok if you can subscrible in my channel as well hi hi look OM my channel is in português because de need material for brasilians ok so 73 kiping on.

How would you measure the impedance of the window line feeder design at the frequency you are interested in? Sorry if this is a basic question but measuring capacitance and impedance at frequency seems difficult. I could see adjusting a tuner and then measuring that to figure it out.

what about manufacturing your own window or ladder line? I've seen a few different way to make your own but I'm not sure what the proper specs (narrow or widely separated conductors) should be?

So obvious a thought, you wonder why you haven't heard of it before! I'm going to have to find Part 2 now.

I did that idea on 10 meters. It was on 2 separate antennas though. I am a old fashioned Ham in that I learned CW with a Novice license in the late 60s. X-WN7LTX, but currently KG7IRJ Ohio Extra.

very entrusting concept.