Care and Feeding of a New Antenna.

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N8CPA, Mar 21, 2009.

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  1. N8CPA

    N8CPA Ham Member QRZ Page

    As I ponder a new home in my near, but not yet immediate future, I am thinking out my antenna plan. I want to avoid some of the minor RFI issues of my current installation by using antenna base couplers (probably SGC) as opposed to in station ATU's.

    Doing some research on EFHWA's (for the acronymically challenged, End Fed Half Wave Antenna(s)), I came across the B&W version. It is 110 feet long and coupled to ground at both the feedpoint and the far end. And, since the two grounded ends are connected by a counterpoise, can anyone explain to me how that is NOT just a delta loop with a buried edge?

    Do the balun at the feedpoint and the matching network at the far end really make it any different than a loop? What's in that network, anyway?
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    What's in the "network" is a 500 Ohm 200W non-inductive resistor.

    This is actually an "opened up" T2FD terminated antenna, and not a partly buried delta loop, nor is it an EFHW. In fact, it's not resonant on any band as I recall, although it's "close" on 80m.

    It actually kind of sucks. I had one in 1978, brand new, from B&W. AFAIK they haven't changed the design. I installed it with the connective ground wire (in my case, #12AWG copper, laying on the ground) and an 8' ground rod at each end. It was "passable" on 80m, not good on 160m and nowhere near as good as my 40m inverted vee hanging from a tree limb at 50 feet on 40 meters. I had its center supported by a rope over a tree limb at about 35-40' above ground, which I believe is exactly what B&W suggested.

    It improved a few dB when I added a bunch of radials at the feedpoint, to supplement the ground rod.

    But in all, it's not much of an antenna. My inverted vee for 40 and Butternut HF6V with 50 radials for the higher bands rang rings around it at the time.

    WB2WIK/6
     
  3. N8CPA

    N8CPA Ham Member QRZ Page

    Thanks for the response. I will not try to duplicate that design when I build it.

    However, I am still thinking about an 80M EFVee matched at the feedpoint and worked against a rhombic shaped field of buried radials. I'll see what EZnec says.
     
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