A network administrator is installing an outdoor wireless point-to-point bridge between tw… — Cisco CCNA

A network administrator is installing an outdoor wireless point-to-point bridge between two campus buildings. The access point transmitter power is configured to $14\text{ dBm}$ , the coaxial cable connecting the access point to the antenna introduces $3\text{ dB}$ of attenuation, and the directional antenna has a gain of $16\text{ dBi}$ . What is the Effective Isotropic Radiated Power (EIRP) for this wireless installation?

$27\text{ dBm}$ Answer
B
$33\text{ dBm}$
C
$11\text{ dBm}$
D
$1\text{ dBm}$

Answer

The Effective Isotropic Radiated Power (EIRP) is

27\text{ dBm}

The correct calculation for Effective Isotropic Radiated Power (EIRP) accounts for the total power output from the transmitter, minus any insertion losses along the transmission cable, plus the passive power gain provided by the antenna. Computing

14\text{ dBm} - 3\text{ dB} + 16\text{ dBi}

gives

27\text{ dBm}

Step-by-Step Solution

Identify the given radio frequency values

Transmitter Power (

P_{\text{tx}}

) =

14\text{ dBm}

, Cable Loss (

L_{\text{cable}}

) =

3\text{ dB}

, Antenna Gain (

G_{\text{antenna}}

) =

16\text{ dBi}

These parameters determine the total power radiated by the antenna in isotropic terms.

Apply the standard EIRP formula

\text{EIRP} = P_{\text{tx}} - L_{\text{cable}} + G_{\text{antenna}}

Cable attenuation reduces signal power before it reaches the antenna, while antenna gain focuses and boosts the radiated signal power.

Substitute the values into the formula and calculate

\text{EIRP} = 14\text{ dBm} - 3\text{ dB} + 16\text{ dBi} = 27\text{ dBm}

Combining the transmitter output, cable attenuation, and passive antenna gain yields the total effective radiated power.

Key Concept

Effective Isotropic Radiated Power (EIRP) Calculation

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