[TowerTalk] Inv L Directivity

[Jim Miller]

Same here.  Modeling has always shown the direction favors (although
slightly) the directions AWAY from the top wire.

73, de Jim KG0KP

----- Original Message ----- 
From: "David Gilbert" <xdavid at cis-broadband.com>
To: <TOWERTALK at contesting.com>
Sent: Friday, August 31, 2007 5:40 PM
Subject: Re: [TowerTalk] Inv L Directivity


>
> Could you guys maybe have it reversed?  Every time I've modeled an
> Inverted-L with EZNEC the directivity is in favor of the direction AWAY
> from the top loading wire.  The only exception I've found seems to be if
> I assume perfect ground, in which case there doesn't seem to be any
> significant directivity.
>
> To be sure, the "directivity" doesn't represent much forward gain in any
> case, and in fact compared to a full quarter wave vertical it seems that
> the pattern is simply reduced in the direction of the wire ... not
> actually enhanced in the direction away from it.  But the "front/back"
> looks like maybe a couple of db which might be worth knowing in some
> situations.
>
> 73,
> Dave   AB7E
>
>
>
>
>
> john at kk9a.com wrote:
> > There is enhanced radiation in the direction of the top loading wire,
> > however it is not worth worrying about.  It is about 1db with a 1/4 wl
> > inverted "L" that is 1/8 wl. high.
> >
> > John KK9A
> >
> >
> >
> >
> > To: towertalk at contesting.com
> > Subject: [TowerTalk] Inv L Directivity
> > From: Craig Clark <jcclark at wildblue.net>
> > Date: Fri, 31 Aug 2007 13:33:58 -0400
> > List-post: <mailto:towertalk at contesting.com>
> >
> >
> >>    8. Re: Topband: INV L Directionality
> >>
> >>
> >
> > G3XAP wrote a number of articles in RadCom (RSGB magazine) about this
> > question.
> >
> > December 1973 p 842 "160m dx from suburban sites"
> >
> >
> > November 1977 p 858 "The G3XAP directional antenna from the
> > lower                               frequencies"
> >
> > Ashton's conclusion was there is enhanced radiation in the direction
> > of the top loading wire. His antenna used a 40-60' vertical element
> > and a 130' top loading wire. To get omni-directional performance, he
> > added more top loading wires.
> >
> >
> >
> >
> >
> > 73, Craig Clark, K1QX
> >
> > _______________________________________________
> >
> >
> >
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> >
> >
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