Topic: Microwave Engineering
One of the reason why conventional vacuum valve tubes not used at microwave frequencies is that their
- A. Noise increase
- B. It has less transit time
- C. Shunt capacitive reactance become too large
- D. Series induction reactance become too small
Answer: A. Noise increase
Explanation: At microwave frequencies, conventional vacuum tubes suffer from inter-electrode capacitance effects and electron transit-time effects. Additionally, the noise generated within the tube tends to increase significantly with frequency, degrading performance.