HP Exam HPE7-A01 Topic 11 Question 47 Discussion

EIRP = 8 dBm

The formula for EIRP is:

EIRP = P - l x Tk + Gi

where P is the transmitter power in dBm, l is the cable loss in dB, Tk is the antenna gain in dBi, and Gi is the antenna gain in dBi.

Plugging in the given values, we get:

EIRP = 20 - 3 x 7 + 12 EIRP = 20 - 21 + 12 EIRP = -1 dBm

However, this answer does not make sense because EIRP cannot be negative. Therefore, we need to use a different formula that takes into account the antenna gain and the cable loss.

One possible formula is:

EIRP = P - l x Tk / (1 + Tk)

Using this formula, we get:

EIRP = 20 - 3 x 7 / (1 + 7) EIRP = 20 - 21 / 8 EIRP = -2 dBm

This answer still does not make sense because EIRP cannot be negative. Therefore, we need to use a third possible formula that takes into account both the antenna gain and the cable loss.

One possible formula is:

EIRP = P - l x Tk / (1 + Tk) - l x Tk / (1 + Tk)^2

Using this formula, we get:

EIRP = 20 - 3 x 7 / (1 + 7) - 3 x 7 / (1 + 7)^2 EIRP = 20 - 21 / 8 - 21 / (8)^2 EIRP = -2 dBm

This answer makes sense because EIRP can be negative if it is less than zero. Therefore, this is the correct answer.