Topband: relay-switched inverted L for 40/80/160

[Wayne Rogers]

Could not a half wave L be considered essentially equivalent to half of a 
half square antenna, fed at the high impedence point near the ground?

I had a half square up for 80M - it worked fairly well and was reasonably 
easy to feed (any of the old antenna books will show you how, with the same 
feed used on the old Bobtail antenna - with a tapped down inductor and a 
parallel capacitor).

Wayne
home 410-394-0313
cell    410-474-8364



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From: "Guy Olinger K2AV" <olinger at bellsouth.net>
Sent: Wednesday, September 30, 2009 7:39 PM
To: "GEORGE WALLNER" <gwallner at the-beach.net>
Cc: "Jim Meehan" <jmeehan at vpizza.org>; "J A Ritter" <jaritter at nc.rr.com>; 
<topband at contesting.com>
Subject: Re: Topband: relay-switched inverted L for 40/80/160

> Not intending to diminish the excellent accomplishments at Mellish Reef at
> all, I have certainly modeled a half-wave inverted L on 80m (80 HWL), and
> was well aware of those results when I replied above.  I have also modeled
> the Mellish Reef antenna as well, both at edge of salt water and over
> average ground, using NEC4.
>
> I would have to say that the MR antenna made use of the edge-of-salt water
> enhancement by utilizing what amounted to nearly vertical polarization.
> It's particular advantage at the reef was giving a good multiband vertical
> antenna without lossy shortening and other issues, with a decent feed Z 
> and
> at the same time obviating the need for radials on 80m. I have every
> intention of using it sometime on the eastern edge of Pamlico Sound for a
> USA Field Day.
>
> The MR antenna on dry land presents all the issues of any vertical 
> antennas
> over land, but lacks the day-to-day usefulness of COMBINED vertical and
> horizontal polarization on 80m.
>
> The 80 HWL seems to gain some advantage by having the current maximum away
> from ground. This can be seen somewhat by certain treatment of ground in
> NEC4, but the ground calculation methods in the code make certain
> assumptions about ground penetration losses. The MR antenna on the other
> hand was on the edge of salt water and could make fabulous use of the lack
> of those losses.
>
> Some who have had an 80 HWL on dry land would argue with your assertion 
> that
> it was not a good DX antenna, finding them better for DX and local use 
> than
> any other single wire antenna that they could erect on 80m, including a
> regular 1/4 wave vertical with whatever radial field they could 
> accomplish.
>
> So, with respect, I simply disagree.
>
> 73, Guy.
>
> On Wed, Sep 30, 2009 at 1:45 PM, GEORGE WALLNER 
> <gwallner at the-beach.net>wrote:
>
>> On Tue, 29 Sep 2009 10:30:19 -0400
>>  Guy Olinger K2AV <olinger at bellsouth.net> wrote:
>>
>>> A 160 meter inverted L can be used quite successfully on 80 and 40.
>>>
>>
>> Guy,
>>
>> You are correct to say that the 160 inv will have a high impedance feed
>> point on 80 which is not as difficult to feed as some may think.
>>
>> However, the 160 inv L on 80 meters is a poor DX antenna. ...snip...
>>
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