Assoicated Universties, Inc.

Richard F Bradley

David H Parker

John M Payne

Rohit S Gawande

A wideband antenna is disclosed. The wideband antenna comprises an inverted cone, at least one sinuous arm coupled to the cone, and a ground plane behind the apex of the cone. The sinuous arm comprises at least two active resonators.

Inverted conical sinuous antenna above a ground plane

A rangefinder system employs three laser rangefinders for determining three dimensional coordinates, each rangefinder using a steerable mirror for aiming the rangefinder beams at a series of retroreflectors. The beams are modulated at 1.5 GHz. The system includes a signal at an offset frequency of 1 kHz for phase detection. A digital phase detector under control of a local computer, as is the mirror, computes phase difference which is used to measure the distances to the retroreflectors. Correction is made for zero point phase drift of the circuit of each rangefinder and a benchmark reference to a distant retroreflector corrects for atmospheric effects on the measurements. A central computer directs the implementation of the tasks of the local computers of each rangefinder and computes and displays trilateration computation results made from the three rangefinders. The system can measure the distance to five different points per second with ranges up to 120 m at all accuracy of about 50 .mu.m.

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Charlottesville, VA, United States of America

Richard F Bradley