Topic: Communication Systems
10 Watts RF power is transmitted with a circular polarized antenna having gain of 10 dB. A receiving antenna has vertical polarization. The path loss is 100 dB. The receiving signal is
- A. - 83 dBW
- B. - 80 dBW
- C. - 86 dBW
- D. + 80 dBW
Answer: A. - 83 dBW
Explanation: Transmit power $P_{t}=10\text{W}=10\text{dBW}$. Transmit gain $G_{t}=10\text{dB}$. The path loss is $100\text{dB}$. Because there is a mismatch between a circularly polarized transmitting antenna and a linearly (vertically) polarized receiving antenna, there is a polarization loss of 3 dB. Received power $P_{r}=P_{t}+G_{t}-L_{path}-L_{pol}=10+10-100-3=-83\text{dBW}$.