Radio Ham interviewed about Fractal antenna

The web stuff was pulled after 9/11.I pulled it.

Fractal antenna research is now going on everywhere, except Antarctica.Even in ham radio.

Anyone catch the fractal antenna talk at Dayton by young man who is a KD0? Would have enjoyed hearing it.

73,
Chip W1YW

 

Old NEws

This is old news... I saw science shows on fractal antennas two years ago...

 

Who says the antenna is sunlit?

 

If we compare a full wave loop with a theoretical gain of 1 over a dipole to your fractal full wave loop we now have a loss of 1.2 db.

You only shrunk a 1/4 wave (per side) loop antenna to a 1/8 wave loop antenna (per side). You did not do anything with a dipole.

You also mentioned “no componants”. May want to change that to “no discrete componants”. Any time you have wires running in opposite directions in such a short distance (wavelengthwise) you have distributed inductance and capacitance. It appears that you are using these factors to your advantage.

I never stated that geometry is not warranted. One needs electrical symmetry in an antenna. What I think is not warranted is the term ‘fractal’. To me it appears that the term ‘fractal’ is a buzzword thrown out to give this antenna (and other antennas) some mystique and draw attention away from the fact that it is a compromise antenna.

I think I have come to the end of this topic. I appreciate your clarification of areas which supports my point of view.

Isn’t Socratic dialog a fantastic tool??????

Ron - KI4TI

 

Hi Ron,

ALL of these are dipoles. The Moore quad is a larger folded dipole with gain. The gain is caused by the presence of two in phase current maxima which are parallel and spaced by 1/4 wave.

A Moore quad is an array. When you change any array spacing the constructive interference changes. If you want to use an antenna that has 4 times the outer area of the fractal=-well!-- go use the Moore quad!

If you want to take the SAME OUTER FORM FACTOR for both fractal and Moore quad well, TADA! The fractal now has 2+ dB OVER the Moore quad.
That's because on that same size it now has 4 current maxima as opposed to the two of the Moore quad. If you want lower gain--go use the Moore quad!

The antenna has--let me repeat for emphasis--NO COMPONENTS. It is a bent piece of wire with NO COMPONENTS. Obviously its equivalent circuit--which changes dramatically with frequency BTW--is written up with L's, C's, and R's. Can YOU show us the equivalent circuit--one equivalent circuit-- for this fractal antenna ? Getting out your freshman ECT class text book won't help: there are oodles of nodes, some of which merge in the spectrum, and the equivalent circuit looks different at each node. In other words--THERE iS NO OBVIOUS REALIZABLE EQUIVALENT RLC system for this antenna, as its nodes each have a different equivalent circuit, and you can't separate them out without switching. You can't do what this antenna does by throwing a bunch of L's and C's together.

I know you don't like the word fractal. So what? I don't like the word 'poop'. But if I use the word 'poop' everyone knows what I mean. We use the word 'fractal' because 'fractal' invokes a design path ---DEFINED BY GEOMETRY--with versatility and uniqueness--I said uniqueness-- not acheived by other antenna methods, because GEOMETRY MATTERS.

Now: if you want to produce a really small AND crappy antenna, your options are limitless. I understand Mickey Mouse makes a good antenna. Geometry doesnt matter when making crappy antennas. It is an equal opportunity option.

I strongly resent the insinuation on 'mystique'. Who the heck presented them that way? Why should I take responsibility for the silliness of others? Name one person who has done MORE to display the physical insight posed by fractals in electronics.

Oh, its that WORD again... ;-)

Saying 'this is a compromise antenna' is like saying ' I am human'. Well, can you name even ONE antenna that isn't a compromise?

?

73,
Chip W1YW

 

A mathematical monster Ron...monster!

;-)

73,
Chip W1YW

 

I guess you have a valid point, Ron. The photo could have been taken at an early morning hour before sunrise with a UV-rich, bright white floodlight source on the right side of the antenna, washing it with light that looks like sunlight.

Although I suspect the astronomer left yet another flaw in the image assuming that no one would notice. Just like the spacing and sizing of the parasitic elements.

73.

 

Right, the PBS show cited by G4TUT was aired in October, 2008.

 

Evolution?

That antenna was first announced as a Two Element Fractal Quad for 10M -- Fracvert and its variants, Cohen-Dipole Beams -- From N1ZKT , and has since grown another element, apparently.

 

Couple more fqy fotos

KF7BS's 2 el FQY on cover of 73 Oct 1999; front pix of a 3 el FQY. Circa 2003. Just a reminder...when making Yagis, you have different inductive lengths for driven, reflector, and directors. Ask yourself: with this design, can I make ALL of them on the same jig--yet add/substract little rectangles or line lengths to meet that requirement for the three different inductive lengths? Think about the ways that you can change inductive length on this antenna...

73,
Chip W1YW

 

Useful information, finally

KB7BS's directions for building the antenna; includes dimensions.

 

KB7BS Fractal

No "copyright ripoff" here.

 

Always comparing one thing to something totally different.

Lets try a bit of a different direction. Lets compare your antenna to say . . . . . your antenna!!

If we straighten out your kinky antenna into a Moore quad we will have a 1.2 db gain. If we rekink your antenna we will lose 1.2 db but will shink the size of the antenna.

Back to my original posting. Giving up performace for a smaller package.

Now I'm done.

Ron - KI4TI

 

Claim of 3dBd

Don't finish things off yet, Ron. One of the ham constructors claims 3dBd. In the forward direction.

To that I say, "two horizontal dipoles stacked in phase" yields 3dBd and bidirectional gain at that.

Really, I think ole' Chip was onto something and didn't realize it.

 

Non-Inductive, Convectively-Cooled Dummy Load

Bird Electronics has been struggling all these years trying to conduct dissipated power away from carbon-ceramic elements, through mineral oil, to a bunch of fins. And, those fins must allow sufficient convective heat flow to cool things down. At times difficult to do indoors. The low viscosity mineral oil can also be a problem as it is a hazardous waste if it leaks, and it can ignite very readily. Never mind about attempts to use non flammable fluids like PCB cut with trichlorethane and such. The EPA frowns upon such ideas.

To make a long story short, one could realize a decent, non-reactive dummy load by carefully going back and forth with conductor paths such that adjacent paths cancel/null the magnetic field. The idea of hanging enough rod in the open air to dissipate 2000 watts is possible, if the rod is carefully bent such that fields cancel. And, at 50 ohms, 2000 watts is only a little over 6 amperes RFcurrent. Isn't symmetry useful? You bet!! Probably best to use nichrome wire/rod as its total resistance from all the folds and bends must be 50 ohms.

For purists, one could encase the carefully folded, back and forth rod menagerie within a chicken wire cage to make sure the electric field is also quashed completely. At least at VHF and lower frequencies.

Sufficient air flow along radiator fins is always a concern as noted above. But, with a symmetrical, outdoor dummy, convective air flow over and through the rods would take care of the heat dissipation problem. Perhaps adding a few chickens to the cage would be adaptive and efficient as well, since their metabolisms would benefit from the warmth a ham with full legal limit tuning his amp could provide on a cold Massachussets Winter night. And, if the birds are added, don't forget to collect the droppings as it could get messy with lengthy tune ups.