Will,
I've installed the ELT antenna a number of ways.
I've installed an AAE carbon fiber antenna with a splitter for a handheld a
ntenna to also connect to for better backup com options. VHF only
I've simply installed the whip antenna with a radial ground plane equal to
the antenna length in the rear floor and a small support for the antenna ti
p to prevent it from making noise.
I've installed a tail mounted dipole unit onto a tail post before finishing
(no com antenna near it).
Normally the Artex or now discontinued AmeriKing were mostly installed belo
w the baggage bay for ease of service. It was simple to run a coax to the
whip antenna supplied or an AAE carbon antenna. The new 406/121.5 dual fre
quency whip antenna Artex uses is supposedly good for both frequencies. Fo
r VHF 121.5 the ground plane for a quarter wave is 33-36 inches but some do
a half 1/4 wave so about 8.5 inches diameter, but I find the signal weak u
sing a handheld vhf on 121.5 using an 8 inch circle alone. Since the Arte
x 345 is a 15 inch whip antenna a simple 15 inch radius ground plane of 4-8
radials works fine.
I always had to laugh at myself when explaining to a customer that placing
the ELT antenna and the com also in the mid fuselage was interesting. As t
he ELT only works when you crash so who cares about spacing the antennas ex
cept for reflection, then if separated by 36 inches, reflection is not an i
ssue. Heck in our composite aircraft I wonder if we could just use the gea
r leg as part of the dipole. Some smart guy needs to look into that.
Just run a couple of tapes about 30 inches long out from the hat section in
the drawing I've attached, and it works. Normally I tack the legs with su
perglue then lay a thin bit of glass over the fragile copper tape. Some us
e a copper braid and some just run aluminum strips using aluminum tape but
if using tape make sure you remove the glue at the contact points to assure
a good ground. If near the side of the fuselage just run the spider web o
ut one side. It still works but is a bit directional. I won't run a radiu
s up the fuselage wall vertically where it can reflect back at the antenna.
We don't know what direction the fuselage will end up in a crash but instal
l the antenna within 20 degrees of vertical and near the fuselage centerlin
e or the inspector will die of a heart attack.
Best Regards,
Bud Yerly
My ELT is an EBC 302 121.5 and 243.0 VHF/UHF Easy to install but the alkal
ine battery is expensive and can corrode destroying the unit. Replacement
for a 406 model is prohibitively expensive.
-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of rparigoris
Sent: Saturday, January 07, 2023 2:38 PM
Subject: Europa-List: Re: ELT position and antenna
Hi Will
Forgot to mention, on both of our ELTs, Mfg said if their antenna wasn't us
ed, unit would not be officially blessed. Both said OK to extend antenna lo
cation with coax. Both suggested using a ground plane. That said won't do y
ou much good if upside down.
Ron P.
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