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Re: Helix vs. loopers



Steve and all
I believe simply lengthing a helix will reach a point of diminishing returns.  It would be better to stack a couple or even four twenty or so turn turn helix antennas (from VE3NPC).  You could  with proper phasing generate a CP signal from a couple of loopers.  I just haven't heard of anyone doing that, though it looks good on paper.
73 Bob W7LRD
Seattle

-------------- Original message -------------- 
From: Steve Raas <sraas@optonline.net> 

> In reading much of the discussion that has hit the BB lately in regards to 
> antennas I figured Ide toss in my questions to the group. 
> 
> 
> 
> In trying to figure out which style antenna is going to suit my needs best I 
> have a few questions. 
> 
> 
> 
> #1 Is a linear polarized antenna less efficient than a RHCP antenna when 
> trying to receive or transmit to a rhcp signal / receiver? 
> 
> 
> 
> #2 If yes.. in theory how much? 
> 
> 
> 
> #3 In looking @ pre-built helix options for 1.2g I have found the DSH23-12 
> which is a 23 cm RHCP 12 turn helix 14.5 dBic gain in a machined radome for 
> best weather protection. 1.2-1.3 GHz bandwidth. 50 ohm feed wit h N (f) 
> connector on 8" backplane. All stainless hardware; Designed for PHASE 3D 
> uplink operation. Wide bandwidth actually covers from 900 - 1600 MHz ( 
> copied verbatium from the www.directivesystems.com website. In looking at 
> the specs of this helix, it seems it may not have the desired gain for P3E 
> or others. In 'theroy' is it possible to make a 24 turn helix , and if so 
> would I be correct in thinking that double the turns would provide at or 
> near 3.0 db of additional gain? 
> 
> 
> 
> #4 If yes to question 3 would this antenna be @ or near double the physical 
> length? 
> 
> 
> 
> 
> 
> In a email I sent to Dave @ Directive he told me that the loopers he has can 
> be arranged for vert/linear or horizontal polarization, so I do think that a 
> looper although a great antenna may not be the best single antenna solution 
> for 1.2 Uplin k. 
> 
> 
> 
> Thoughts, Ideas & comments please. 
> 
> 
> 
> 
> 
> -Steve Raas 
> 
> N2JDQ 
> 
> FN20vg 
> 
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