Cavita' per i 2m
http://www.southgatearc.org/techtips/cavityfilter.htm
Cavita' per i 23cm
http://techdoc.kvindesland.no/radio/feed_lines/20060919164750176.pdf
http://scottyspectrumanalyzer.com/cavity.html
http://www.w6pql.com/23cm_filters.htm
13cm 3 pole bandpass filter
http://www.qsl.net/g0ory/2.3g/bpf/13bpf.html
