[Top] [All Lists]

[TowerTalk] Re: Force12

To: <>
Subject: [TowerTalk] Re: Force12
From: (Tom Rauch)
Date: Thu, 11 Oct 2001 12:24:25 -0400
Hi Yuri,

The personal attacks aren't really necessary. I try hard to make 
sure what I say is accurate. The only reason I am involved in 
reflectors is to learn or help others lean, not to insult people or be 
> Where did I say anything about antenna elements?
> Thicker more lossy conductor (same material)? 
> Hmmm!
> Tom is "right" even when he is wrong, I rest my case (again :-)
> Yuri, K3BU

Factually, a coaxial dipole is more lossy than a typical copper 
dipole for a few reasons. One is the conductor is woven, and woven 
conductors have significantly more loss than smooth conductors.

That why all the lowest loss transmission lines, for a given line 
size, use smooth conductors in the current carrying areas.

Second, there is a poor dielectric coating the wire (the PVC 
Jacket) at the area where the electric field ism most concentrated.

Third, coax makes a very low Q lossy stub. Q of a 1/4 wl RG-58 
stub is only around 15-25.

If you take the time to read analysis of the coaxial dipole appearing 
in QST and other ARRL publications, you will see they also agree 
the bulk of the broadbanding by using a coaxial dipole is caused by 
added loss, not by stub effects. You can find the efficiency 
problems described on 9-4 of the 18th ARRL Antenna Handbook. 

That is what I measured here, and what is commonly published by 
many sources (like Walt Maxwell in Reflections).
73, Tom W8JI 

List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!!

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>