Microwave System Engineering Using Large Passive Reflectors

This paper will provide the microwave engineer with the basic techniques of microwave system engineering using large passive reflectors and will outline the many advantages of their use. Small passive reflectors of the "periscope type" have been used for many years on microwave systems. Large passive reflectors have also been used but to a much lesser degree. Large passives may be used at intermediate points on long (200 miles or more) microwave links in lieu of active repeaters. Most microwave engineers have little knowledge of system engineering using these reflectors. This paper describes their use in both the "near" and "far fields" in line-of-sight systems and describes how they may be used on non-line-of-sight systems (tropospheric scatter and diffraction systems). Formulas are developed and graphs provided which will enable the microwave engineer to determine the path loss of multihop passive reflector systems. Large passive reflectors should be considered as another tool which can be used by the microwave engineer for planning and engineering communications systems. When used effectively with line-of-sight, diffraction and tropospheric scatter modes of propagation, communication systems may be engineered more economically, with more reliability and with a decrease in the operating and maintenance problems.