No, a top hat or tee vertical will have virtually no radiation from the flat
top if designed correctly. I have a website on that type of antenna at
http://www.kn4lf.com/kn4lf2.htm .
On an inverted L the flat top portion radiates a high angle horizontally
polarized signal. The field strength of this horizontal radiation varies
depending on the length of the flat top. A 65 foot flat top on a 130 foot long
160 meter inverted L will radiate a considerable high angle horizontally
polarized signal, though it's down considerably compared to the low angle
vertical component. If you fold the 65 foot flat top back on itself at 32.5
feet the horizontally polarized radiation is further reduced.
BTW I have a website on the inverted L at http://www.kn4lf.com/kn4lf52.htm but
it's a 7/16 w/l linear loaded inverted L.
--... ...--,
Thomas F. Giella, KN4LF
Lakeland, FL, USA
Grid Square EL97AW
kn4lf@arrl.net
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com
Radiowave Propagation Yahoo eGroup:
http://groups.yahoo.com/group/radiowavepropagation
----- Original Message -----
From: Al Williams
To: towertalk@contesting.com
Sent: Friday, July 14, 2006 10:44 AM
Subject: Re: [TowerTalk] Question on Multiple Inverted L Antennas
Isn't an inverted L antenna just one (Unique) configuration of a top hat
vertical?
k7puc
----- Original Message -----
From: "hasan schiers" <schiers@netins.net>
To: "Robert Chudek - K0RC" <k0rc@pclink.com>; <towertalk@contesting.com>
Sent: Friday, July 14, 2006 7:03 AM
Subject: Re: [TowerTalk] Question on Multiple Inverted L Antennas
> Inverted L's have similar bandwidth to a 1/4 wave vertical...and it isn't
> "real broad" without excessive return loss. All measurements need to be
> made
> at the feedpoint. I've done radial studies on my Inverted L and as radial
> numbers increase, vswr bandwidth DECREASES, exactly as it should. I made
> measurements of feedpoint Z at resonance and 2:1 vswr bandwidth with the
> following number of radials:
>
> 0,2,4,6,8,12,16,26
>
> VSWR bandwidth was best with 0 radials (DUH...lots of resistive loss!)
> Feedpoint Z dropped from 79 ohms with 0 radials to 29 ohms with 26
> radials.
> The predicted Rrad is 25.4 ohms
>
> 73,
>
> ...hasan, N0AN
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