Ever hear of the new "fractal antenna" designs ?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KD7SIZ, Dec 15, 2010.

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  1. KD7SIZ

    KD7SIZ Ham Member QRZ Page

    PBS had a little story ( part of a larger story about fractals ) about the new "fractal antenna" designs. They are much smaller and much more powerful than usual antennas.

    Do a google search of "fractal antenna" to learn more about them.

    A ham radio operator bent his antenna wires to look like some of the designs in nature. He was surprised to discover that these new fractal antennas worked very good on just the first try.
     
  2. W2ILP

    W2ILP Ham Member QRZ Page

    Fractal Antennas

    I think that we may have discussed fractal antennas here on QRZ several years ago when that PBS documentry was aired.

    It is incorrect to claim that antennas are "powerful". It is however correct to clam that some antennas may be more proficient as radiators or receivers of radio waves than others. That concept is based on how efficient they can be for their size...or better still for the "aperture" that they present. It is known that trees and even entire forests tend to branch with common ratios in order to present their most efficient exposure to sunlight. Generally a fractal antenna is geometrically a structure that employs a certain amount of continous branching (each branch is branched and again branched and so on) rather than a straight monopole, dipole or a coil.

    The ham in the documentry experimented with fractal based antenna designs. Printed fractal antennas are now being used for microwave cell phones...and fractal tank resonators are also used in some microwave transceivers.

    w2ilp (Impersonating Large Plants)...by designing antennas in their image.
     
  3. W1YW

    W1YW Ham Member QRZ Page

    Ham, I am.

    Actually few fractal antennas invoke branching.

    Both fractal element antennas and fractal resonators were first published in Comm Quarterly in August, 1995. There are multiple patents.

    Dont make ham antennas . Strongly suggest you support the extant ham vendors and keep them pumpin out ham product. Might present something at Dayton if asked.

    A new ham article on ham fractals is in the works.

    In the meantime, you might enjoy these videos:

    http://www.youtube.com/watch?v=QWd0nEXFnrE

    http://www.youtube.com/watch?v=_JpMJTJXf28

    N1IR= Chris Johnson today

    W1YW = N1IR in 1987 era.

    73,
    Chip W1YW
     
  4. NA0AA

    NA0AA Ham Member QRZ Page

    Back in the late 70's I think it was, the rage was the 'batwing' antenna design - they even had a picture of a broadcaster using one! It was a piece of PC board in the shape of a bat [flying rodent, not baseball/cricket], and the radiating element for CB was a pair of 2 watt, 100 ohm, carbon resisters in parallel connected to the coax feedline. These were attached at the base of the bat.

    Now that I think back on this, I wonder if I missed this being in a April issue.

    I know that there are many antennas that work well in theory, some that work well in reality.

    Commercial antenna vendors? Sure, but not for wire antennas.

    Anyone selling fractal wire yet? Oxygen free by preference.
     
  5. KE5FRF

    KE5FRF Ham Member QRZ Page

    Chip,

    Are you actually DISCOURAGING hams from building homebrew antennas?
    If the ham vendors can't offer a product that is of equal or superior quality to a homebrew antenna at a cost effective price, then why should I worry if they are running on tight profit margins? Sounds to me that they need to rethink their business model.

    My mission in life as a ham is NOT to worry about the state of ham equipment manufacturing, save for perhaps state of the art rigs and a few other things that aren't so easy to homebrew. The US economy wouldn't even be blemished if all ham antenna sales went away.

    That doesn't mean that I hope ill for these manufacturers either, but I see way more value in self education by building your own rather than paying someone good money to build something that is so easy to homebrew.
     
  6. 4L4AGU

    4L4AGU Ham Member QRZ Page

    I have Fractal antenna from an soviet military portable radar. Will take photos if anyone interested. It's dated back 80s.
     
  7. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Pictures Please!
     
  8. 4L4AGU

    4L4AGU Ham Member QRZ Page

    ok, but it will take a while (it's in another city). 1st when I saw it, I thought it was just someone's phantasy on PCB. it looks nearly like one on attached picture. Of course, it's not rounded - all turns are square, and all 4 leafs split to two "sub-leafs" as on left, I was just lazy to draw them all. Total dimension is about 15x10cm.

    Was used in this:

    http://117orb.at.ua/Stati/AR_RLS01ik.jpg
     
  9. KD0CAC

    KD0CAC Ham Member QRZ Page

    I watched that show the 1st time around and again the other day .
    So far fractal design appears to be for higher frequencies , above UHF .
    Have not found anything indicating that it would work on HF , which is what I am playing with now , other bands in the future like below HF & GHz .
     
  10. W1YW

    W1YW Ham Member QRZ Page

    I am on 20 right now; I suspect that qualifies as an indication. I also was running Europe on 40 cw a few min ago.

    Call me on 14230 right now.

    Chip W1YW
     
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