Advanced Qualification · A-002 Advanced components and circuits · A-002-012-005
Resonant cavities are used by amateurs as a:
- A high-pass filter above 30 MHz
- B narrow bandpass filter at VHF and higher frequencies
- C power line filter
- D low-pass filter below 30 MHz
Correct answer: B — narrow bandpass filter at VHF and higher frequencies. From the official ISED question bank, verified word for word.
Why
Resonant cavities act like hollow metal boxes that naturally vibrate at one specific frequency, allowing only a very narrow slice of signals to pass while blocking others. The full explanation — and one for every question — is in Pro.
Practise this section
Advanced components and circuits: semiconductors, amplifier classes, oscillators, mixers, filters and digital logic.