REFLECTOR: ELT

[Jim Agnew]

I mounted mine to the fore & Aft to the top front of the pilots baggage strake.  Since the AK450 can also be used as a portable with voice transmit capabilities all the pilot does is open the door get out reach in and unsnap the unit and you are out of there.
 
Jim
 
James F. Agnew Jim_Agnew_2 at Yahoo.Com Tampa, FL Velocity 173 Elite Aircraft Completed & Flying 


----- Original Message ----
From: Al Gietzen <ALVentures at cox.net>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Wednesday, January 25, 2006 1:51:30 PM
Subject: RE: REFLECTOR: ELT



Subject: RE: REFLECTOR: ELT
 
Al-
 
  We are building a XL-FG and I built a Jim Weir antenna on the spar and we mounted the ELT to the side of the keel as close to the fish fin as possible.  This puts it under our baggage compartment but not behind the vanity panel.
 
Craig
 
That seems like a good approach; the dipole eliminating the need for ground plane.  
 
There may be a question of signal strength distribution.  I’m no expert on antennas, but I think the dipole on the spar would have good signal strength in the vertical direction, and horizontally in the direction of the fuselage axis, but poor horizontally in the direction of the dipole; in fact essentially zero off the ends of the dipole, especially for the 121.5 frequency as it won’t “bounce” very well. For the 243 frequency it is probably less important.  The signal would be more likely picked up by satellite, but maybe some blank spots for S & R.
 
Of course we don’t know the orientation of the antenna when we need this thing, but assuming the airplane in basically in a horizontal position, the monopole (vertical with some sort of perpendicular ground plane) would have good signal in all horizontal directions, but poor straight up (or down).
 
That’s assuming I understand things correctly, of course.
 
Like most things, we take the compromise that is most doable.
 
It does seem that having the transmitter reasonably accessible so it can be taken out of the airplane with the portable antenna would be a good idea.
 
Al
 
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