This is insanity
The specs as called out in the manual are crazy. They want a minimum 24" diameter grounding plane, with 48" being optimal. The book also says you can't substitute the antenna unless it complies with this:
VSWR @ 121.5 MHz <= 2.5:1
VSWR @ 406 MHz <= 1.5:1
Does anyone know of any antennas that meet that requirement, hopefully in a short whip, or a blade?
I see builders who are no doubt desperate to get their plane finished pushing it to the limits of where it won't throw an error code but probably will never reach the satellite. Many have grounding planes of a few inches. Some have installed them in the cockpit and those are not only inconvenient but don't have a grounding plane either. The closest was the last post (which the poster admits is not pretty), but it is still between the rudder and elevator, so will block 3/4 directionality. Please note, I am not criticizing any of them.
One person who swapped with another antenna in a parallel thread said "It broadcasts on Comm frequencies... ...so it should be ok", which a 406mhz is not.
ACK makes a blade, but it costs $1k (seriously!?!), but you are prohibited from putting it on the bottom.
My biggest concern is going upside down in a tail dragger, so why is the bottom bad? If I am crashing in the sticks, and end up not being able to walk away or call on the radio, or a cell, isn't it much more likely that I will be upside down?
The Search & Rescue and Civil Air Patrol guys always say to follow the book, and not to put it near the tail feathers, as it blocks transmission. And the mothership says to do what everyone else says not to do.
I understand this needs to reach a satellite (in space obviously), so I can't see a weak signal doing that, and almost everyone tests only the 121.5 frequency (even the book says not to test the satellite part).
<Ok, End RANT>
So are we all just closing our eyes and hoping for the best? I can see the accident reports saying "ELT installed not in accordance with recommended practices".
I thought maybe on top of the rudder, but there is no viable ground plane, and that will be the first thing to go if the plane flips.
Has anyone tried a mod to the tail fiberglass, to locate the antenna right in front of the rudder by an inch of so?