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. W1YW

    W1YW Ham Member QRZ Page

    Considering we came first, it could hardly be a variation of that design, which it doesn't resemble anyway.

    Also, do you understand WHAT their cloak is? Do you understand that it requires a grid of repeated objects AS THE THING TO BE cloaked? :)

    Please: tell us how this in any way related to the practical realization of a wideband invisibility cloak shown at:

    http://www.youtube.com/watch?v=_JpMJTJXf28So


    W1YW
     
    Last edited: Jan 20, 2011
  2. K4WGE

    K4WGE Ham Member QRZ Page

    Harry Potter and the Half-baked Prof

    ?

    Is that why Chip failed to get tenure at Hogwart's?
     
  3. W1YW

    W1YW Ham Member QRZ Page

    Ahhh!

    Number 2 AND Number 1--all rolled into one!
     
  4. W8JI

    W8JI Ham Member QRZ Page

    I don't know about that.

    It is very common to measure things incorrectly and hatch a new invention or theory.
     
  5. W5DXP

    W5DXP Ham Member QRZ Page

    Here's a good example:

    http://www.w8ji.com/inductor_current_time_delay.htm

    "Measure things incorrectly and hatch a new invention or theory", e.g. that the delay through a large air-core loading coil bears any resemblance to the standing wave current phase shift even when an extreme mismatch exists.

    Pure standing wave current doesn't change phase over each 1/2 wavelength so it cannot be used to measure delay through a wire or through a coil. Reference: Antennas by Kraus, 3rd edition, Figure 14-2 where the actual current phase shift changes by 3 degrees over the entire 1/2 wavelength of a dipole (a standing wave antenna).
     
  6. M3KXZ

    M3KXZ Ham Member QRZ Page

    "Current does not have to do with how far charges move in a second but rather with how many charges pass through a cross section of wire on a circuit............The rate at which charge enters the external circuit on one end is the same as the rate at which charge exits the external circuit on the other end. Current - the rate of charge flow - is everywhere the same. Charge flow is like the movement of soldiers marching in step together, everywhere at the same rate." (ref http://www.physicsclassroom.com/class/circuits/u9l2c.cfm )

    Suppose a way to to make a comparison would be to use time domain reflectometry on a terminated line of a certain length, and then compare it with measurement on same length of line formed into a solenoid.
     
    Last edited: Jan 20, 2011
  7. N5RWJ

    N5RWJ Ham Member QRZ Page

    Hi Chip,seems like a lot of QRM on this topic today. Chip could you talk some on the future of Fractal antennas, also on Fractal antennas for 75,40, and 20 meters?
     
  8. K1BQT

    K1BQT Ham Member QRZ Page

    "Perhaps you can articluate the process by which 'time tells'?"

    I was thinking of the time-honored (and time-consuming) process of validation and verification that occurs normally within the scientific community. You know, like Cecil and Tom are doing right now!
     
  9. W5DXP

    W5DXP Ham Member QRZ Page

    Unfortunately, that applies to a DC steady-state circuit, not to an RF distributed network. For a transmission line or coil that is 180 degrees long (series self-resonance) the rate of charge flow into one end of the coil is equal to the rate of charge flow into the other end of the coil.
     
  10. W5DXP

    W5DXP Ham Member QRZ Page

    You mean like this graph of load current phase shift vs source current reference phase=0 through a Texas Bugcatcher coil as the load resistance is varied?
     

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