Неотражающие фильтры CВЧ (обзор)

Abstract

The subject of the review is non-reflective microwave filters (NF) of various types, also called absorption filters. Brief information from the history of the creation of SF is provided. Directional filters are considered, which served as the prototype of non-reflective filters, NFs on lumped elements, non-reflective filters with loaded sections of transmission lines, non-reflective filters on coupled lines. All of these types of devices differ from conventional filters in that they remain matched both in and out of the operating passband (or non-passband). Part of the unwanted frequency spectrum of the signal entering the input of such filters is not reflected back to the signal source, but is absorbed in the filter itself. This operating principle of the NF ensures effective matching with other devices in the system, which is a key characteristic when designing wideband equipment with multiple output and output channels tuned to different frequencies. An assessment is made of the current state of development, prospects for miniaturization and improvement of the characteristics of non-reflective filters.