Question
What is the effective isotropic radiated power (EIRP) of a repeater station with 200 watts transmitter power output, 2 dB feed line loss, 2.8 dB duplexer loss, 1.2 dB circulator loss, and 7 dBi antenna gain?
Answer Options
- A) 159 watts
- B) 252 watts
- C) 632 watts
- D) 63.2 watts
Correct Answer: B
Explanation
Effective Isotropic Radiated Power (EIRP) is the power radiated by the antenna in the direction of maximum gain, relative to a theoretical isotropic radiator. The calculation is similar to ERP, but the antenna gain is already specified in dBi (decibels relative to isotropic).
First, calculate the total gain/loss in dB: G_{Total} = Antenna Gain - Feed line Loss - Duplexer Loss - Circulator Loss = 7 dBi - 2 dB - 2.8 dB - 1.2 dB = +1 dB. The EIRP is 200 W \times 10^{(1/10)} \approx 200 W \times 1.259 \approx 252 W. Therefore, the EIRP is approximately 252 watts.
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