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here's some of my observations on antenna installations
Questions:
- What antenna works best (given that it is too late to embed in the
vertical stab)?
The commant CI-122 bent whip always works if it's installed properly. I've had good success with the archer dipole antennas, but their installation is a bit more challenging.When installing the SA-006 Archer antenna in the empenage, when it starts to bend so it's not perpendicular to the earth, it becomes ineffective. That doesn't mean it won't work, it's just less effective.
- What size ground plane do I use?
The radius of the ground plane should be the same as the length of the antenna,generally. There a whole lot of techno stuff about wave length that doesn't pertain to Lancairs because of our size limitations. I generally try to make the ground plane as large as possible with out it starting up the sides of the aircraft. Once it's no longer parallel with the base of the antenna, it's ineffective. The dipole antenna does not need a ground plane.
- Do I ground the ground plane and, if so, where?
The ground plane will be grounded through the coax.
- Do I allow the antenna wire shield ground to electrically connect to
the ground plane, or should they be insulated? (I can imagine grounding
the ground plane to the battery in back, having it contact the antenna
shield which grounds to the bus in front, and having that situation
cause a loop which might have adverse consequences)
Let the coax and the radio ground the ground plane.
- How critical is it to use the newest kind of coax? The old coax is
embedded down the side of the plane away from all signal wires, and if
I replaced it I'd have to run the new one up the center with a lot of
other wires...
The rg-400 coax is better that the rg-58, but both work if properly installed. It's best to separate the coax from other wires, both power and signal. But, again, with our limited space compromises have to be made. If properly installed, rg-400 will usually shield the wire well enough to run in close proximity with other wires.
Jon
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