[TowerTalk] Fwd: Bandwidth of a 1/4wl 80m vertical

[HansLG at aol.com]

Hi there,
 
Wasn't there a way with "bazooka" antenna to get a wider bandwidth of any  
antenna? I will remember that you could use a parallel resonator to extend the  
bandwidth on any antenna. An other way was to have a "return" parallel with 
the  radiator such as you see in a the folded dipole. They have wider bandwidth 
than  the "simple" dipole. I have seen a wideband navy GP antenna that had a 
wire from  the top to ground of the radiator that widened the bandwidth. That 
should be a  possible method for your 80 M vertical. The "wire extender" should 
be thinner  than the radiator.
 
What I remember (from my old and lousy) memory if you have different  
diameter on the dipole and the "fold-over" a large diameter dipole with a thin  fo
ld-over the feeding impedance is closer to 75 ohms. If the diameters are equal  
you have a feeding impedance closer to 300 ohms. Consequently, if the fold-over 
 part has a larger diameter than the "dipole" part the feed impedance will be 
 even higher that 300 ohms. (This was used as a trick to keep a 300 ohm  
feeding impedance in TV yagi in the "old" days)
 
73 de N2JFS
Hans
 
  
____________________________________
 From: w8zn at comcast.net
To: towertalk at contesting.com
Sent: 3/16/2009  3:18:28 P.M. Eastern Standard Time
Subj: [TowerTalk] Bandwidth of a 1/4wl  80m vertical




Hi all,

To those running 80m 4 squares,  what kind of bandwidth do you typically see? 
Is it about the same as a typical  dipole or 1/4wl sloper? Does anyone know 
if using a larger radiator (such as  Rohn 25 vs 3"/4" irragation pipe) gives 
broader bandwidth or is the diameter  to wl ratio just too small to make any  
diff?

thanks!!

Terry
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