Distributed-element filter
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A distributed-element filter is an electronic filter in which capacitance, inductance, and resistance are not localised in discrete capacitors, inductors, and resistors as they are in conventional fil
Figure 1. A circuit featuring many of the filter structures described in this article. The operating frequency of the filters is around 11 gigahertz (GHz). Further details below.
The PCB inside a 20GHz Agilent N9344C spectrum analyser showing various microstrip distributed-element filter technology elements
Figure 2. A parallel-coupled lines filter in microstrip construction
A microstrip low pass filter implemented with bowtie stubs inside a 20 GHz Agilent N9344C spectrum analyser
Mechanical filter
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A mechanical filter is a signal processing filter usually used in place of an electronic filter at radio frequencies. Its purpose is the same as that of a normal electronic filter: to pass a range of
Figure 1. A mechanical filter made by the Kokusai Electric Company intended for selecting the narrow 2 kHz bandwidth signals in SSB radio receivers. It operates at 455 kHz, a common IF for these receivers, and is dimensioned 45 mm × 15 mm × 15 mm (1.77 in × 0.59 in × 0.59 in).
Mechanical filter from a telephone carrier system using torsional resonator elements
Details of a mechanical filter using torsional resonator elements
Details of a mechanical filter using disc flexural resonators