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LF: Re: UNIPOLE V INV-L ?

To: <[email protected]>
Subject: LF: Re: UNIPOLE V INV-L ?
From: "Alan Melia" <[email protected]>
Date: Fri, 8 May 2015 17:28:13 +0100
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Hi G,
Well the Laws of Physics dont change however much one might wish it :-))
 
The unipole will be approx -3dB ERP on the inv L
 
Effective height of unipole approx half physical height
Effective height of inv L same height with 1.5*h top is approx 0.9* physical height
 
inv L disadvantage.....requires another support and insulators
inv L advantage ........over poor ground with the same feed-point grounding the inL will have lower ground loss and higher capacity. Over good ground or sea-water this advantage may disappear, but losses will be low anyway.
 
I think this folded monopole is covered in Rik's tutorial, the extra wires are just "matching" they dont increase the radiation resistance. Commercial stations like grounded aerials for lightning protection.
 
Alan
G3NYK 
----- Original Message -----
From: Graham
Sent: Friday, May 08, 2015 4:54 PM
Subject: LF: UNIPOLE V INV-L ?

UNI-POLE  V  INV-L ?
 
 
Assuming  a robust   ATU and   earth   
 
What would be the  advantage  / disadvantage   of  say  a   40  foot  uni-pole  ,   to  a  conventional     40 x 60   ft  inv L   at  MF ?
 
tower  and  side wire  or   RG8U  / copper  pipe  construction ? .........  -3 dB  of a  similar size loop  ?
 
73-Graham
G0NBD
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