[Antennas] Re: Elevated Ground Plane Question

Wed, 09 Oct 2002 21:59:05 -0700

Is not there an inverted "L" that loads at the top, at the junction of the 
2 lines of the el?

Chris opr VE7HCB

At 10:56 AM 2002-10-09 +0200, alexander eban wrote:
>...this is NOT top loading. A few years back MFJ put out what was called at
>the time ;Top Fed Antenna. The rationale behind it was that since the energy
>goes out at a slent angle from the radials and/or grounplane, feeding the
>antenna at the top and moving the ground plane at the top would result in
>radiation parallel to the ground. Actually it was shot into the ground! That
>antenna was never  popular, probably because a lot of guys figured out
>something's fishy. The only good thing of that antenna was the size. I
>wouldn't recommend it, certainly not as a main antenna!
>                         73 and all the best
>                                 Alex    4Z5KS.
>
>
>-----Original Message-----
>From: [email protected] [mailto:[email protected]]
>Sent: Wednesday, October 09, 2002 5:07 AM
>To: W2WU
>Cc: [email protected]; [email protected]
>Subject: [Antennas] Re: Elevated Ground Plane Question
>
>
>Top loading is the most efficient form of loading a shortened vertical!
>That's true in broadcast or amateur circles :)
>
>But of course the question here does not concern the vertical
>radiator but the ground radials...and they should be kept out of the way of
>the vertical element....
>
>Chris
>WB5ITT
>
>W2WU wrote:
> >
> > A small "top hat" on a vertical is an old broadcast antenna trick. I
> > agree that putting radial on top of the antenna would severely limit
> > current flow and proper radiation.
> >
> > In fact a large hat would cancel proper radiation. See: Dr. Brown &
> > his paper on vertical antennas. Also see "Antenna Engineering
> > Handbook" by Jasik, John Battonson B.E. & other applicable engineering
> > texts.
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