The j-pole antenna is fixed...

Discussion in 'Amateur Radio News' started by KX4O, Jul 9, 2020.

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  1. KX4O

    KX4O Ham Member QRZ Page

    …or invalidated depending on your point of view. Presenting the...


    Two new patents address shortcomings of the 84 or more year old traditional J antenna design. This effort features the following highlights.
    • The research includes extensive J antenna myth busting, validating the concerns trumpeted by many over the years, using method of moments and finite-difference time-domain simulation techniques confirmed by real antenna chamber measurements.
    • The utility patent voluntarily catalogs and reviews many published papers and related patents.
    • The addition of a mast decoupling stub mitigates the propensity of the J antenna to energize a conductive mast. No more does the J antenna require an ideal length of conductive mast to perform correctly.
    • The parallel nature of the mast decoupling stub maintains the slender nature of the J antenna.
    • Internalizing the feed line of hollow pipe J antennas eliminates the traditional, but famously awkward, external feed line dressing. Additionally this internal feed approach performs double duty by naturally decoupling the feed line from the antenna.
    • The improvements maintain the J antenna's notable direct electrical connection through robust antenna conductors to the mounting structure and, hence, ground from dc to just below the primary design frequency.
    • Design patent -
    • Utility patent -
    • Background and research -


    Whether or not this functional version of the J antenna has utility to users remains to be seen. At least this one works.
    W7GST, W7YBY, KK5JY and 8 others like this.
  2. W1YW

    W1YW Ham Member QRZ Page

    Congrats on the (somewhat) new patent, John.

    But--not sure why this invalidates anything. We all know most of the crap was wrong anyway...

    The tale is told in the currents.

    This utility patent is assigned to the FBI (USG). Assuming a useful need in ham radio, beyond other options, how do you anticipate licensing for hams?

    Chip W1YW
    KG4BFR and KX4O like this.
  3. ND5Y

    ND5Y Ham Member QRZ Page

    Will you sue people who build those without paying you royalties?
  4. KX4O

    KX4O Ham Member QRZ Page

    Thanks. This process has been a very long road.
    Not nearly enough know... including prominent J antenna makers and their customers. Same goes for the oft quoted "gain over regular J" SlimJIM gain claims.
    Work in progress... with another department... going at half speed due to coronovirus. :|
    Last edited: Jul 9, 2020
    N0TZU likes this.
  5. KX4O

    KX4O Ham Member QRZ Page

    Not my call as the USG owns it. Will know more in a few months most likely.
  6. W1YW

    W1YW Ham Member QRZ Page

    Probably the same self-'experts' who assert that fractals only increase loss.... and are so inefficient that they cause farm fields to burn down .


    Anyway, nice work John:)

    Chip W1YW
    NL7W and AC0OB like this.
  7. K3FHP

    K3FHP XML Subscriber QRZ Page

    How much 'decoupling' " is needed at the feed point of an end-fed 1/2 wave(with 1/4 wave matching section)?
  8. KM1H

    KM1H Ham Member QRZ Page

    AFIK, that mast decoupling stub is not new and has appeared in a magazine in the past.

    AC7LX, KW4UP and KA4DPO like this.
  9. WD5HNI

    WD5HNI XML Subscriber QRZ Page

    Fab a single J antenna years ago for 6, seems ok, but when the tuff gets going, the 7 element elevated off the groud
    wins hand down. Besides the majority of the hams today do not build antennas! Just too easy to get the laptop out
    and order a dipole or made up ant today.

    KI2H likes this.
  10. KD7TWW

    KD7TWW Ham Member QRZ Page

    73, KD7TWW

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