Which of the following is most frequently used as a band-pass or notch filter in VHF and UHF transceivers?
A Sallen-Key filter
A helical filter✓Bonne réponse
A swinging choke filter
A finite impulse response filter
Explication
A helical resonator is a helically wound quarter-wave line inside a shield can, which gives high Q in a physically small package at VHF and UHF. That is why helical filters are the usual band-pass and notch elements in transceivers for those bands.