Microwave Systems for Fixed and Mobile Services

Microwave radio relay systems now in operation are mainly analog FM systems. The state of the art for these systems is recalled. During the last years microwave radio relay systems are rapidly moving towards digital transmission. Principles of these systems together with the main problems to be solved are presented. Of special importance in this context is the efficient use of the available frequency spectrum. One approach to use frequency spectrum most effectively is single sideband modulation. Another approach for thin route systems are point to multipoint radio relay systems. These systems provide demand assigned access to the transmission channel. Mobile microwave systems can provide countermeasure-and interception-free communications over distances of some km. Special attention has to be paid to the problems of fading and shadowing, to be encountered by suitable system lay-out.