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		MJKTuck(at)cs.com Guest
 
 
 
 
 
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				 Posted: Mon Jan 20, 2020 4:13 pm    Post subject: Dipole com antenna | 
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				I'm thinking of switching from an external monopole type com antenna 
 (long rod sticking out at an angle with copper tape in a radiating 
 pattern on the fuselage floor) to a Bob Archer SA-006 dipole antenna.
 
 The dipole appears looks like a '3' and made from thin sheet aluminum. 
 This '3' shape is what you attach the coax shield too (ground). The core 
 of the coax attaches to a small insulated aluminum plate in the middle 
 of the 3 shape.
 
 Does anyone know how it works (the theory) and does anyone have one in 
 their Europa? How is it?
 
 Regards,
 Martin Tuck
 N152MT
 
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		h&jeuropa
 
 
  Joined: 07 Nov 2006 Posts: 654
 
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				 Posted: Tue Jan 21, 2020 8:23 am    Post subject: Re: Dipole com antenna | 
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				Martin,
 
 This is a simple dipole antenna with the radiating elements folded back to make it more compact.  It is a very basic design and should work well.  Be aware that it needs to be mounted on the side of the fuselage, not the floor or top and oriented so the coax is parallel to the longitudinal axis.
 
 I've used similar antennas for ham radio work for many years.
 
 Here is a link with more information:  
 
 https://sportcraftantennas.wordpress.com/2010/09/16/antennas-for-no-metal-airplane/
 
 Jim Butcher
 
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		MJKTuck(at)cs.com Guest
 
 
 
 
 
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				 Posted: Tue Jan 21, 2020 6:22 pm    Post subject: Dipole com antenna | 
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				Hi Jim, thanks.
 
 I now have a Dynon radio under the floor of the baggage bay so the coax 
 will route up the back of the baggage bay to about half way, then run 
 longitudinally mid-fuselage for about 18 inches at which point it will 
 mount to the SA-006 antenna plate. So, yes, the antenna will be mounted 
 vertically. I guess a portion of the coax will not be parallel to the 
 longitudinal axis due to the radio location.  I figured it was more 
 important to have a short coax cable between the box and antenna.
 
 I would still like to know the theory on how it works though, "simple 
 dipole antenna with the radiating elements folded back" doesn't help me 
 visualize what is going on.
 
 Regards,
 Martin
 
 On 1/21/2020 10:23 AM, h&jeuropa wrote:
 
 
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		h&jeuropa
 
 
  Joined: 07 Nov 2006 Posts: 654
 
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				 Posted: Thu Jan 23, 2020 8:46 am    Post subject: Re: Dipole com antenna | 
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				Martin,
 
 The Wikepedia article is a pretty good explanation, 
 
 https://en.wikipedia.org/wiki/Dipole_antenna
 
 Because the ends are folded on the SA-006, the impedance of the antenna needs to matched to the feedline and the com output.  Archer uses a gamma match for this.
 
 Your planned installation sounds fine.  
 
 A dipole in the rear fin per the build manual also works very well but access on a completed airframe is somewhat difficult.
 
 Jim
 
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		MJKTuck(at)cs.com Guest
 
 
 
 
 
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				 Posted: Thu Jan 23, 2020 7:04 pm    Post subject: Dipole com antenna | 
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				Thanks Jim,
 
 I think later Europas had premoulded (hollow) fins. Mine has the 
 original foam core fin. However it sounds like the fuselage is fine also.
 
 How it all works - well, it is all magic.  
 
 Regards,
 Martin
 
 On 1/23/2020 10:46 AM, h&jeuropa wrote:
  	  | Quote: | 	 		   
 
  Martin,
 
  The Wikepedia article is a pretty good explanation,
 
  https://en.wikipedia.org/wiki/Dipole_antenna
 
  Because the ends are folded on the SA-006, the impedance of the antenna needs to matched to the feedline and the com output.  Archer uses a gamma match for this.
 
  Your planned installation sounds fine.
 
  A dipole in the rear fin per the build manual also works very well but access on a completed airframe is somewhat difficult.
 
  Jim
 
 
  Read this topic online here:
 
  http://forums.matronics.com/viewtopic.php?p=494417#494417
 
 
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