Filter design for modern communication systems

With usable RF spectrum as one of the most expensive-and usually unavailable-natural resources, frequency subdivision techniques are critically important for protection of both the content producer and the consumer. The use of filters to provide walls to ensure isolation of users from one another is common, but the design of such filters is difficult because of proximity. With spectrum more costly than hardware, the ordered metrics for filters are performance, size, reliability, and lastly, selling cost. In this paper we will discuss topology and manufacturing technology for the more recent approaches to implementation of such filters.