Early results: Very low-level propagation measurements on the Ottawa River

The effects of anomalous propagation on the accuracy of low-angle radar tracking are discussed, perhaps for the first time. A novel technique is described for carrying out very low-level propagation measurements. It is based on a large sampled aperture antenna system which is instrumented with both radio and meteorological sensors. Early results are given of collocated radio (angle-of-arrival) and meteorological measurements which were recorded on the Ottawa River near Ottawa, Canada. In particular, a direct comparison is given of measured angle-of-arrival deviations and values predicted from meteorological measurements, as well as results showing angle-of-arrival errors for propagation in evaporation ducts.