Topic: Radar and Navigation
A radar system uses TWTA as high power RF source for transmiting 300 W Peak Power. The efficiency of transmitter during pulse is 75% and the transmit duty is 25%. If the DC power required during pulse off period is 20W. The average power dissipation in TWTA is
- A. 81.25 W
- B. 125 W
- C. 50 W
- D. 40 W
Answer: D. 40 W
Explanation: During the pulse ON period, transmitted power is 300 W and efficiency is 75%, so total input DC power is $P_{del} = \frac{300}{0.75} = 400$ W. The power dissipated during ON time is $400 - 300 = 100$ W. During pulse OFF period, the DC power (and thus dissipation) is 20 W. The average power dissipation is calculated over the duty cycle: $P_{avg} = (100 \times 0.25) + (20 \times 0.75) = 25 + 15 = 40$ W.