Bert Modderman Engineer
23cm interdigital filters.
i have a new filter for atv and ssb for 100 euro.
i will post a picture as soon as i have a better html editor then notepad.
attenuation on 950mhz 60db, on 1800mhz 80db and on the second harmonic 55db.
bandpass characteristic for atv tuned is about 0.2-0.25db loss in passband.
tuned to 1296mhz and with sma connectors i can go a little below 0.2db.
this filter is already in use at many many ssb stations around the world.
i also have a filter that filters 950 and 1800mhz a bit worse but will have 0.15db loss.
i remember i made this filter only once but i lost its specs but it was very low loss.
for tuning filters i use a very expensive vector network analyzer from hewlett packard.
rigol and signal hounds and simular network analyzer equipment do not come close to
the accuracy of hp. so beware, do not retune my filters, you can actualy make it worse without knowing it.
i have even seen several times that the rigol actualy shows a filter making gain instead of loss...
i can make filters to your specifications. ( i do not have a design principle yet for 23cm with notch filters.)
23 cm low loss 0.3db filter for tx 100 euro
1245-1320mhz bandpass or 1296mhz bandpass and little less then 0.5db loss. 100 euro.
very good for blocking 900 1800 2200 and 13cm signals.
bandpass of the atv tuned version with 0.75 db loss +/- 0.1db ripple.