Use a Horn spkr. and about 120 watts of power. Like the spkrs used on police 
cars. These aren't exactly directional but are designed to put the main part 
of the power in a more or less straight ahead alignment. Other than that use 
the same type horn spkr. and build an encloser around the spkr. like a cannon 
and that should be a little more directional....73....KB0OYD...Springfield 
o.
--- GEcho 1.11+
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