[Elecraft] [OT] end-fed halfwave antennas

[Bill Johnson]

Wes,  Thank you for the references!
73,
Bill
K9YEQ



-----Original Message-----


It is really unfortunate that advice like this continues to be...excuse the pun...propagated on forums such as this, when there is so much published information to the contrary freely available on the Internet and/or in books in your local library.

I have already quoted one source but I'll do it again for emphasis. (Hopefully, the formatting will survive)

  Devoldere in "Low-Band DXing", Chapter 9 says:

        4.3. The Radial System for a Half-Wave Vertical
        Here comes another surprise. A terrible misconception
        about voltage-fed verticals is that they do not require either a
        good ground or an extensive radial system.

        4.3.1. The Near Field
        If you measure the current going into the ground at the
        base of a λ/2 vertical, the current will be very low (theoretically
        zero). With λ/4 and shorter verticals, the current in the radials
        increases in value as you get closer to the base of the vertical.
        That’s why, for a given amount of radial wire, it is better to
        use many short radials than just a few long ones.
        With voltage-fed antennas, however, the earth current
        will increase as you move away from the vertical. Brown
        (Ref 7997) calculated that the highest current density exists
        at approximately 0.35 λ from the base of the voltage-fed
        λ/2 vertical. Therefore it is even more important to have a good
        radial system with a voltage-fed antenna such as the voltage-fed
        T or a λ/2 vertical. These verticals require longer radials
        to do their job efficiently compared to current-fed verticals.

Another invaluable source is Rudy Severns, http://www.antennasbyn6lf.com/ Rudy's work is meticulously measured, beautifully documented and presented.  He has written many articles for QEX, which are available on his site or via an Internet search.

Wes  N7WS

On 2/12/2017 5:17 AM, Guy Olinger K2AV wrote:
> ....
>
> So it is that over the years, especially on 80m, many have shown up on 
> the air with amazingly inefficient antennas on 80m. They would check 
> into 80m traffic nets with really puny signals. Many of these weak 
> signals were excellently solved by going to an end-fed halfwave L fed 
> with a matching network (usually a tapped coil in parallel with a 
> capacitor) against some horrible ground. Grounds like a couple of 
> buried bare wires running away from a basement window, or even a 
> ground rod, did not matter in series with the end-feds' feed Z's in the 1000, 2000 ohm range and up.

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