Use of cancellation techniques in the measurement of atmospheric crosspolarisation

Some of the errors implicit in atmospheric crosspolarisation-measurement systems are given, together with their limitations on the accuracy of the resultant measurements. A cancellation technique is described that allows the `clear-weather¿ performance of measurement links to be considerably improved. The limitations due to rainfall of such a cancellation system on the accuracy of crosspolarisation measurements are investigated, and the system is shown to be preferable to a conventional one.