[Antennas] " G5RV " TYPE ANTENNA / "CUSHCRAFT MA5V"ANTENNA QUESTIONS

Tue, 2 Jul 2002 09:48:23 -0400

Gee... I have TWO large metal tool boxes (length wise ) sitting on my
450 ohm feed line to keep it from moving around in the room...  Does
that mean it will not work???  Hummmm, I seem to be working the world,
all kinds of DX, using Milli Watts...  Humm, must be something different
in Georgia.  8-).

I have never worried about "metal" in the vicinity of the feed line for
the last 49 years of hamming. 

Jerry 
W3CDE 
Atlanta, GA 

-----Original Message----- 
From: Harvey&Bessie [ mailto:[email protected]
<mailto:[email protected]> ] 
Sent: Tuesday, July 02, 2002 9:37 AM 
To: George, W5YR 
Cc: K6MHE; Chris BONDE; [email protected] 
Subject: Re: [Antennas] " G5RV " TYPE ANTENNA / "CUSHCRAFT MA5V"ANTENNA 
QUESTIONS 

I should like to point out that this discussion seems to be centered 
around metal objects in the vicinity of the open-wire line. As pointed 
out, metallic objects too close to the line (I favor 5 times the line 
spacing for good isolation) can unbalance the currents in the line and 
can cause an impedance "bump" in the line. Such impedance irregularities

are of little or no concern where a tuner is involved, but must be taken

into consideration if the line is any part of an impedance-matching 
scheme. However, we must also consider non-metalic objects within the 
field of the line. Unless these are made of excellent dielectric 
materials, they have the effect of absorbing power from the line, thus 
contributing to line loss, which can be considerable in some cases. 
Harvey W4TG 

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