Duplexer DVB-T TX filter: Technical details
Bandpass is addition of two notches
Three cavities RX to ANT
Reverseded notch TX to ANT
Sum of two notches with six cavities RX to TX
Two left hand couplings are conventional, the two right hand couplings, with plastic spacers are unusual, give reverse notch (not sure how).
SWR of Duplexer filter7 MHz on 70 cm, not great but probably affected by tuning, possibly by coupling design.
Coupling for reversed notch needs further investigation