MICROWAVE COMMUNICATION TECHNOLOGY

Communications represent the largest microwave market segment, worldwide. Analog terrestrial microwave links carry more than half of the long-distance communications in the U.S. and in most other countries. Growing and diversifying applications led to spectrum crowding, which demanded better spectrum utilization. This is being implemented in two ways: (1)through improvements in the spectrum efficiency, i.e., by increasing the transmission capacity within a given channel bandwidth, and (2)through spectrum sharing between different transmission systems (e.g., terrestrial and satellite). The advent of digital microwave transmission introduced additional elements of complexity. Under these circumstances, the microwave industry faces unprecedented challenges in the development and manufacture of communications equipment, components and devices. The talk is intended to concentrate on technological developments in response to the prevailing operational requirements and competitive pressures. Most major development efforts are oriented at high-capacity digital transmission in the preferred communication bands below 12 GHz. Microwave power amplification seems to be attracting the greatest attention as GaAs F= amplifiers become increasingly successful in competing with TWTs, but other related development efforts are making significant progress, as well. Other areas of progress in microwave communication technology to be highlighted in this talk are the ongoing expansion into the millimeter-wave range, the growing point-to-multipoint transmission requirements, the beginning of commercial spread-epectrum transmission applications, and last—but not least-the continuing progress in the development of analog microwave transmission equipment. Terrestrial microwave communications owe their initial rapid growth to the availability of the previously developed radar technology, and they continue to benefit from this and from the other areas of military and commercial microwave systems development, including satellite communications which introduced a new element of competition. The more recent development of microwave receivers for direct satellite broadcasting promises to bring about new designs and manufacturing techniques that could be advantageously applied to equipment for terrestrial microwave communications, especially in reducing manufacturing cost. These important interrel~