Electronics: New Wave

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A Rensselaer Polytechnic Institute group is investigating the practicality of a subway that would be suspended by compressed air in a cylindrical tube and whip along at 350 m.p.h., driven by a microwave-powered propeller. The microwaves would be generated at stations along the length of the route and transmitted efficiently within the subway tube, which would act as a giant wave guide. And some day, fixed-station helicopters, miles in the air, might be used to beam microwaves hundreds of miles in a straight line to other fixed-station helicopters—instead of from hilltop to nearby hilltop, as is now done. How would such a helicopter fly? By means of an electric engine powered by a microwave beam located directly below on the ground.