On Sat, Jan 25, 2003 at 06:06:34PM -0500, Don Stackhouse @ DJ Aerotech wrote:
> OK, now it's my turn to ask a question for all of you antenna gurus out
> there.
>
> Let's assume we have a small airplane such as a Mosquito class sailplane or
> an indoor model. We know that ideally we should have a 39" antenna, all
> straight-out, but there physically isn't room for it on a model this size.
There is, unfortunately, no easy answer >:-(
> However, we do have two wings, which each have room for a short antenna,
> maybe 14" to 18" long each.
> If we run an antenna out each wing, with one as the conventional antenna
> and the other connected to the receiver's negative bus to act as a ground
> plane,
Not a good idea, basically that antenna would not be right for the
frequencies you are using.
> For cases where even this is too big, what about using one of those little
> tuned-coil antennas in one wing as an antenna, and another pointed the
> opposite direction in the other wing as a ground plane?
Any attempt to shorten the aerial,winding it on a former, attaching a
tuning coil to a shortened element, etc all attract penalties. There
are losses within the system, the signal strength will be reduced
compared to a normal antenna. Might be O.k...with a small model
you are going to be flying fairly close in anyway.
If I was faced with this problem I would probably try :
Running the antenna up to the top of the fin, back down to back
of fuse. and letting it trail.
I don't, personally, like long lengths of trailing antenna wire
so my preffered method would be to try:
Run antenna to top of fin, back down inside fin and return inside
the fuse. I think the seperation would be sufficient to prevent
problems. Only sure way is to range check and see if it's O.K
I run my antennas to the top of the fin on my gliders.
Don't they make helically wound "rubber duck" antennas that you
could try.... admittedly I have seen mixed views on them.
Reg
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