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Re: Topband: Inverted L capacity hat

To: Szegedy <>
Subject: Re: Topband: Inverted L capacity hat
From: Herbert Schoenbohm <>
Date: Sat, 05 Sep 2009 09:19:38 -0400
List-post: <">>

Szegedy wrote:
> 2.If I use 4 top wire ,antenna will radiate 4 direction?  

Normally with four wire top hats of equal length have a cancellation 
effect on unwanted horizontal radiation while adding need length to a 
short Marconi. However they should not be much more than 20-30 feet or 
slope down at more than 45 degrees inregard to the horizontal plane..  
Assuming you have sufficient radials in or lying on the ground, a 65 
foot vertical with 4 25 foot top hat spokes should perform well on 160 
meters.  Your feed point impedance, although I have not modeled this 
configuration, should be in the vicinity of 20 to 30 ohms so proper 
matching is required.  If you have an antenna bridge and you find a 
radiation resistance that is, let say 65 to 75 ohms, this may indicate 
that you need to put down more radials to bring the impedance closer to 
the actual value of the antenna modeled over a near perfect ground thus 
reducing power robbing loss resistance.

Herb Schoenbohm, KV4FZ

> Normal inverted  L radiates only one direction? Lot of difference or not? 
> 3.I have limited space for radial,no space for 1/4 wave radial ,I have only 
> 15m(45 foot) for each direction?
>    Anybody tried to use trap radial? To use a coil or capacitor in each 
> radial? Or not?
> Thanks :Laszlo 
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