"One really needs microwaves to detect a plane flying at high speed"
Actually, not. HF and VHF will bounce quite nicely off a plane. It's quite possible that HF radars can see "stealth" aircraft.
So no, one doesn't need microwaves to detect a plane - actually, use the wrong microwave frequency and atmospheric absorbsion will kill your radar pulse.
Slashdot Mirror
"One really needs microwaves to detect a plane flying at high speed"
Actually, not. HF and VHF will bounce quite nicely off a plane. It's quite possible that HF radars can see "stealth" aircraft.
So no, one doesn't need microwaves to detect a plane - actually, use the wrong microwave frequency and atmospheric absorbsion will kill your radar pulse.