Advanced Qualification · A-002 Advanced components and circuits · A-002-012-006
On VHF and above, 1/4 wavelength coaxial cavities are used to give protection from high-level signals. For a frequency of approximately 50 MHz, the diameter of such a device would be about 10 cm (4 in). What would be its approximate length?
- A 0.6 metres (2 ft)
- B 2.4 metres (8 ft)
- C 3.7 metres (12 ft)
- D 1.5 metres (5 ft)
Correct answer: D — 1.5 metres (5 ft). From the official ISED question bank, verified word for word.
Why
At 50 MHz, a quarter-wavelength coaxial cavity must be roughly one-quarter of the signal's full wavelength to work as a filter. 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.