[TowerTalk] Question on Multiple Inverted L Antennas

[Thomas Giella KN4LF]

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 at 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 at 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 at netins.net>
  To: "Robert Chudek - K0RC" <k0rc at pclink.com>; <towertalk at 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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