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. K4WGE

    K4WGE Ham Member QRZ Page

    QRM?

    1. There is no such thing as bad publicity for Chip. The thread has more than 500 posts.

    2. My impression has been that Chip will be much too busy to answer your question.:)
     
  2. M3KXZ

    M3KXZ Ham Member QRZ Page

    Yeah, I know. :)
     
  3. W1YW

    W1YW Ham Member QRZ Page

    Ahhh!

    You mean like the SCIENTIFIC PAPER with coauthors at Cornell, BU, Vanderbilt, Harvard, and Stanford--that's coming out--PUBLISHED IN A REPUTABLE JOURNAL-- on the wideband invisibility cloak later in the year? Is that the one you mean Rick :)? If so, well, then just ignore it for now. NO Problem:) I've got more interest than I can handle:)

    Or do you mean something else? For example: you may ignore the video if you wish. I am inundated with queries on it as it is.

    73,
    Chip W1YW
     
    Last edited: Jan 20, 2011
  4. W1YW

    W1YW Ham Member QRZ Page

    Most certainly I will write something up on 20M at some point. The first (new ham) paper is VHF/UHF DIY--because that's what people want. I didnt get any substantial feedback on 75 and 40m. It is troubling to say it, but the younger hams apparently aren't as interested in those bands--based on the feedback I got. I like 40, and will be back on 75 in a couple of months, so it IS important to ME. But I don't write for ME :)

    The 'future ' of fractal antennas...too big a topic.

    New stuff coming out everyday...for example, earlier today there was press release regarding a new way of doing heat transfer. My firm divulged the patent filing because of a couple of very recent papers that came out barking up the same tree.

    Fortunately, we planted the tree;-)

    It is common for technology companies not to publish, but to patent. Its really only in the last 25 years that the emphasis on technology PUBLISHING has taken off, because universities have to get these advertisements out to justify grants.


    73,
    Chip W1YW
     
    Last edited: Jan 20, 2011
  5. K4WGE

    K4WGE Ham Member QRZ Page

    Accepted for publication...where?

    As yet unpublished papers don't count in the real world. do they?:confused:
     
  6. W1YW

    W1YW Ham Member QRZ Page

    Cecil, wasn't there some kind of dubious argument coming out of GA, oh, 8 years ago, about there NOT being a current drop across a loading coil--and then someone stuck ammeters up simultaneously on both sides to show there IS?

    You remember that, right:)?

    73,
    Chip W1YW
     
  7. K4WGE

    K4WGE Ham Member QRZ Page

    Red herring?

    How does your post address the validity of The Fractal Antenna Systems video about "cloaking"? Are you just trying to change the subject?
     
  8. W1YW

    W1YW Ham Member QRZ Page

    Yep. So true:)
     
  9. W5DXP

    W5DXP Ham Member QRZ Page

    It's called thread drift. Here's the subject to which I was responding:

    "It is very common to measure things incorrectly and hatch a new invention or theory."

    How well I remember - both rail arguments were wrong. The current "drop" is primarily caused by phasing between the forward current and reflected current. One can assume the coil is absolutely lossless and not radiating and see that same current "drop" due to phasing.
     
  10. W8JI

    W8JI Ham Member QRZ Page

    If something was claimed to be invisible or cloaking, a proper measurement would be to ping it from all angles and polarizations and see what pings back. That's how RADAR works.

    Also, we see reflections from objects with visible light. We just don't know an object is there because it blocks throughput of light.

    I think the only thing happening is the antennas on the back side of the "cloaking" system receive signal from the front side antennas via transmission line effects. The overall system simply has very roughly similar loss through the transmission lines as propagation through space would have, and so looking at the far side tells us nothing about how invisible it is. It's like looking down a coaxial line and saying it is a cloaking device because what goes in the far end comes out the near end.

    If the source antenna and receiving antenna were increased in distance so phase shift though the "cloaking device" would come into play, my bet is it would no longer be so "transparent".

    Also I'd wager it pings back.

    We could duplicate the effect touted on the U-toobe video with a waveguide that goes around the "cloaked objects".

    I would think something more meaningful in measurements would be offered.

    73 Tom
     
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