Topic: Microwave Engineering
For a directional coupler, the quantities I (isolation in dB), D (directivity in dB), C (coupling in dB) are related by
- A. $I=\frac{C}{D}$
- B. $I=D-C$
- C. $I=D+C$
- D. $I=\frac{D}{C}$
Answer: C. $I=D+C$
Explanation: For a directional coupler, Isolation $I = 10 \log_{10}\frac{P_i}{P_b}$, Directivity $D = 10 \log_{10}\frac{P_f}{P_b}$, and Coupling $C = 10 \log_{10}\frac{P_i}{P_f}$. Therefore, $I(\text{dB}) = C(\text{dB}) + D(\text{dB})$.