Atmospheric multipath propagation over a long terrestrial line-of-sight path

Measurements of atmospheric multipath propagation were conducted over an 87.6-km test path in the New England area. Characteristic of this program are (1) the pathlength and its potential for propagation effects not normally found on shorter commercial communication links and (2) an effort to explore the propagation mechanism through coordinated measurements of meteorological and wave parameters. The height difference of 178.6 m between transmitting and receiving antennas was the lowest available to retain line-of-sight clearance at this pathlength and yet produce maximum interaction with stratified regions of enhanced refractivity gradient. Radiosonde derived refractivity profiles were obtained at several locations along the test path when propagation conditions warranted this. Dual receiving systems measured multiple wavefront angles of arrival and delay differences. A 29-ft antenna, continuously scanning in elevation, provided angular patterns with 0.15 resolution at the operating frequency of 15.