Compact Ku-Band Channel Filters for Input Multiplexers

Channel filters in input multiplexers (IMUX) take up a substantial portion of modern satellite payloads in terms of size and mass. This is due to the fact that current channel filters are based on volumetric technology for the manufacturing of the resonators. This technology is needed in order to achieve stringent specifications of satellite communication payload in terms of electrical performances, where high filter quality factor (QL) is needed for flatter and more selective response (Figure 1). The classical way to achieve high QL is to use resonator elements with high quality factor (Q0), since filter QL is directly related with that of the resonator elements (Q0). Furthermore, resonator size and Q0 are closely linked, since bigger cavities show higher Q0 than smaller ones.

The novel approach takes advantage of the fact that filters QL, for a given flatness in the transmission response, also depends highly on the synthesis technique used in the filter design. In this sense, significant gains can be made with the proper synthesis choice. This is the main purpose of this activity.

It is worth to mention that given some particular resonator technology with its associated Q0, when used in a filter and due to physical restrictions, it is not possible to indefinitely increase the filter QL. For that reason, a detailed assessment on current (and future) resonator technologies shall be performed at the beginning of the project, in order to identify the most feasible resonator technologies to be applied at filter level.