Topband: T-loaded vertical

[dj7ww at t-online.de]

Hi Frank,

I just simulated a T vertical 50m away from my 38m high 3L 40m yagi with
EZNEC.
Pattern and gain did not change on the yagi when it beamed 90° away from the
yagi.
Only when I turned the yagi to point to the T antenna gain went down by
0.4dB and front to back by 9dB (was 39). Director parallel to the top load.
Vertical simulated with 30m vertical and 2x 15m horizontal toploads.
No difference with the vertical connected to ground or lifted by 10cm.

73
Peter

-----Original Message-----
From: Topband [mailto:topband-bounces+dj7ww=t-online.de at contesting.com] On
Behalf Of donovanf at starpower.net
Sent: Dienstag, 18. Februar 2020 19:01
To: topband reflector
Subject: Re: Topband: T-loaded vertical

Hi Pete, 


Symmetrical T-verticals offer a performance improvement over 
inverted-L verticals but with a major downside if you operate on the 
higher bands. If the flat top of the T-vertical is near resonance on any 
HF band is will significantly degrade the performance of any Yagi 
antenna within hundreds of feet of the flat top. 


My recommendation: if you're serious about the HF bands don't use 
a T-vertical unless you can locate it far from your Yagis. 


I learned this lesson the hard way years ago with a 70 foot flat top 
on my T-vertical I totally trashed my 3 element 40 meter Yagis 
hundreds of feet away. 


73 
Frank 
W3LPL 

----- Original Message -----

From: "N4ZR" <n4zr at comcast.net> 
To: "topband reflector" <Topband at contesting.com> 
Sent: Tuesday, February 18, 2020 4:45:27 PM 
Subject: Topband: T-loaded vertical 

I keep seeing references to people using symmetrical wire top loading 
instead of the single wire of an inverted L. My question is how to 
calculate the appropriate length for the two top-loading wires. 

-- 
73, Pete N4ZR 
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at <http://reversebeacon.net>, now 
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