File:Waveguide-post-filter.JPG

English: Five-resonator triple-post waveguide bandpass filter made by Ferranti. A length of WG15 (WR112) is divided into five coupled resonant cavities, by fences of three posts each. Each of the two end-cavities is separated from its respective port by a single post and a short adjustment screw. The ends of the posts protrude through each broad-wall of the guide, making them clearly visible from the outside. The resonators are each about 30 mm long and have a central tuning screw. All seven screws are secured by jam-nuts and thread-lock and are normally protected by plastic caps (removed for the photo).

Centre frequency 7.200GHz

Dimensions / mm (averaged and with spurious last digit)

Along guide (post-diameter)<---post-centre-to-centre-distance--->(post-diameter):

(3.18)<---29.40--->(2.82)<---31.34--->(3.18)<---31.55--->(3.18)<---31.34--->(2.82)<---29.40--->(31.8)

Fence pitch across guide: 7.11

Tuning screw diameter: 3.95, insertion ~2

End screw diameter ~2.2, insertion ~2

Guide: WG15-ish (tapers too narrow to too wide)