Topic: Transmission Lines
Return loss of a stand-alone antenna is 10 dB. One 6 dB attenuator with return loss of 40 dB is connected at the input of that antenna. What will be the approximate return loss of the combined (Antenna + Attenuator) port?
- A. 40 dB
- B. 22 dB
- C. 16 dB
- D. 10 dB
Answer: B. 22 dB
Explanation: The incident signal passes through the 6 dB attenuator, reflects from the antenna (which has a 10 dB return loss), and travels back through the 6 dB attenuator. The total return loss from this reflection path is $6 + 10 + 6 = 22$ dB. The attenuator's own return loss is 40 dB, meaning it causes very little reflection itself. Therefore, the dominant reflection at the input port is the 22 dB return loss.