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Re: Topband: Marconi vs. inverted L

To: topband@contesting.com
Subject: Re: Topband: Marconi vs. inverted L
From: Dennis OConnor <ad4hk2004@yahoo.com>
Date: Fri, 4 Sep 2009 05:26:40 -0700 (PDT)
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I got some pm's to my post on the group...
******************************************************************************

I thought the inverted L had a low angle take-off for DX work? It's what I have 
used to work 130 countries in 3 years.
ANSWER
The OP specifically wants to do some DX
contests...  The L has both a low angle lobe from the vertical wire and
a very high angle lobe from the low horizontal wire -which was the
point of my post... This high angle lobe is undesirable in weak signal
DX work because you receive more noise and monkey chatter...  The
balanced top hat of the Marconi suppresses the high angle lobes...  
Now
if you want to talk with the locals who are beyond groundwave but not
far enough out to be in the first low angle lobe skip zone, i.e. in the 
shadow,  then
you need a high angle lobe to fill in...  The L serves both purposes
and is a fine compromise..
.
**********************************************************************
You quote less man made noise on the Marconi.  That's probably never
true. 
ANSWER
The issue in doing weak signal DX work with the L antenna is that
the high angle lobe is hitting the receiver  with noise from the shadow zone - 
i.e. beyond the ground wave and before the first low angle lobe skip zone, 
adding noise to the pass band of the receiver that the Marconi suppresses...  
I do not see how the L would be a quieter antenna than a Marconi - all else 
being equal -  given the additional lobe responses of the L
compared to the Marconi's suppression of high angle signals from the
shadow zone...

The L has a fine reputation as a do it all
antenna - and deservedly so... But for weak signal DX, low angle lobes
only will give the best performance overall

***************************************************************************************

denny / k8do


      
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