[TowerTalk] 160-m Inverted L or Sloper?

Jim Brown jim at audiosystemsgroup.com
Mon Nov 14 16:34:47 EST 2005

On Mon, 14 Nov 2005 14:52:06 -0600, K4SAV wrote:

>I can only think of two possibilities that could cause this.  

There is also antenna directivity, which can be quite significant, 
even with relatively simple wires. For example, my 80/40 dipole at 
home runs east/west, so is pretty dead going west. But if I run it 
as a top loaded wire ( by tying both sides of the feedline together 
and loading it against a counterpoise), it's at least a couple of S-
units better going west on 80 (both transmit and receive). That's 
also a lot of dB. And I've observed this difference for azimuths as 
different as AZ, LAX, WY, and WA. 

Another example -- I have sloping dipoles hung off opposite sides of 
a very big tower (150 ft tall, 35 ft square at the base, 25 ft 
square at the top) at W6BX (see qrz for pix). Based on switching 
between them on various signals, I would estimate their directivity 
on the order of at least 6 dB front to back. Note these are NOT 
slopers -- they have no electrical connection to the tower -- but 
they certainly do interact with it. And I'm not "phasing" them -- 
I'm feeding one or the other at a time. 


Jim Brown  K9YC

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