Topband: T Top Verticals and yagis

[Ed Sawyer]

Guy.  Its interesting reading.  But it makes A LOT of assumptions tied to your promotion of the folded counter poise.  If, in fact, you have invested in a significant ground screen under the vertical feed, you actually WANT the lower angle radiation near the ground.  And if there is no “trade” as to the height and location of the T vs the vertical, you don’t “lose power in the pattern” by having a T.

 

I agree with you that as a compromise antenna, the L has a lot of real world advantages putting energy in a number of directions more favorably than the Top loaded vertical (T or otherwise).  But if you are looking for the comparable efficiency of a full size ¼ wave vertical with 50 – 70% of the height, and you only want pure vertical radiation pattern, there is no comparison between an L and a T with the same vertical height and a good ground radial system.

 

I never knew there was a Folded Counterpoise Society before.  Thanks for sharing.

 

Ed  N1UR

 

From: Guy Olinger K2AV [mailto:k2av.guy at gmail.com] 
Sent: Saturday, February 29, 2020 12:56 PM
To: Ed Sawyer
Cc: TopBand List
Subject: Re: Topband: T Top Verticals and yagis

 

Have to disagree on the no-use-for the horizontal leg. 

 

It fills in the doughnut hole in the high angle radiation, which in contests is very good for keeping others from planting on your run frequency. Also there are high angle path opportunities that are gradually becoming more recognized. PLUS, the horizontal section does not remove power from the vertical wire. In front of the vertical, the direction with the horizontal pulling away from the bend in the opposite direction, there is a good deal of net field reduction at the ground. This power, not lost in the ground, is instead left in the pattern. This is discussed in k2av.com with illustrations. Click on "Design an Inverted L", then down at the paragraph "Vertical WIre part of the L" and following.

 

Also the radiation of the horizontal wire off its end quadrants is vertically polarized, not horizontal. 

 

Not desired energy off the horizontal wire is a gross oversimplification, that has stuck around for entirely too long. 

 

73, Guy K2AV

 

 

 

On Sat, Feb 29, 2020 at 12:38 PM Ed Sawyer <sawyered at earthlink.net> wrote:

Mike, I am not sure where you find your information, but  ALL of the
radiation of a T top vertical is vertically polarized assuming the T section
is balanced.  The whole point of the T is that the horizontal portions of
the radiation cancel themselves out because they are 180 degs out of phase.
Providing loading but not distorting the vertical pattern and not using that
wasted horizontal energy.



An inverted L, while simple, is exactly the opposite. A portion of the
energy is in the vertical section and a portion in the horizontal section.
On 160M, whatever the length is of the horizontal section, its not desired
energy for DX work.  Although it may actually be helpful as a more
all-around antenna for local and DX work for this reason.



The smaller the ratio of horizontal to vertical, the less this compromise
exists.  However very few stations that say they are using an inverted L on
160 have 100ft plus of it vertical.  Much more typical is 50 - 75 ft.  And
the horizontal portion is usually longer, sometime a lot longer, than the
vertical portion.



Ed  N1UR





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