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What's the story with end-fed antenna's?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KI7QVR, Feb 27, 2018.

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  1. KM3F

    KM3F Ham Member QRZ Page

    Problem is the feed point is the physical point of feed from the transmission line (end fed).
    Seems it gets mixed up with the electrical feed that varies all over depending on the physical configuration.
    If there is no intended other half, the feedline becomes the other half right back to the tuner or the transmitter and its attendant problems.
    Then there is a rush to block common mode out at the antenna or close to the transmitter.
    The system has to have a return path back to the transmitter.
    This should be on the inside of the coax feed line shield.
    These end feds are often a pain if the system does not solve for the issues it presents.
    There really should not be any mystery about these if you adhere to antenna theory.
    Good luck.
     
  2. W8IXI

    W8IXI Platinum Subscriber Platinum Subscriber QRZ Page

    Good approach. You don't need anything else to get a wire in the air and get on the air. All first wire antennas are a starting point. None are "perfect" when first installed. Or at least not subject to improvement.

    You don't need an antenna analyzer just yet ( or the advice of those who own one).

    All multiband antennas are a compromise, and in several situations the end-fed is a competitor. Understand that the thread is already rolling on for those who have no concern about your progress as a ham, but only about their own priorities. Let me know if I can be of help.

    Good Luck! 73, Mike
     
  3. N8AFT

    N8AFT Subscriber QRZ Page

    The Zepp antenna has been around since the vy beginning of radio. Yes, the Handbooks are a much ignored resource that has been the standard
    amateur radio knowledge base. I'd much rather take the word from there than hearsay advice too.

    Learn Morse
    Do CW
    73
     
  4. W9XMT

    W9XMT Ham Member QRZ Page

    For those who might appreciate seeing a scientifically-based analysis of an EFHW antenna vs. those based on intuition, hearsay, and marketing statements ...

    The graphic below was generated by NEC4.2, and shows a 1/2-wavelength horizontal conductor fed 24" from one end, with a ~1/4-wave vertical conductor connected at the feedpoint to model the current path along the outside of the outer conductor of a coaxial cable connected there. The red lines in the plot show the relative distribution of r-f current along those conductors.

    The total, free space radiation pattern from this configuration is shown by the crosshatched lines.

    The Wire/Segment info table inserted there shows the conditions at the feedpoint for 100 watts of Z-matched, applied power.

    [​IMG]
     

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