A resonant six-turn loop of closely spaced turns is operating at 50 MHz. The radius of the loop is λ/30. The radius of the wire is λ/300, its conductivity is σ = 5.7 × 107 S/m. Determine the:
a. the directivity of the antenna (in dB)
b. the radiation efficiency
c. the gain of the antenna (in dB)