Correct Answer - Option 3 : 66.66%
Concept:
The antenna efficiency of an antenna is given as:
\(\rm{\eta = \frac{{{R_r}}}{{{R_r} + {R_a}}}}\)
Rr : Radiation resistance
Ra : Effective Antenna resistance
Calculation:
Given:
Radiation resistance (Rr) = 60 Ω
Antenna resistance (Ra) = 30 Ω
\(\rm{\eta \% = \frac{{60}}{{60 + 30}} \times 100\%}\)
\(\rm{\eta \%= 66.66\%}\)
