SOLVED Numerical's - Antenna Theory - Page 3.
6) An antenna in air radiates a total power of 100 kW so that maximum radiated electric field strength of 12 mV/m is measured 20 km from the antenna. Find its: (a) Directivity in dB (b) Maximum power gain if η r = 98%. SOLUTION: a) G = 10 log 10 G d = 10 log 10 (2.16) = 3.34 dB b) G = η r G d = 0.98 x 2.16 = 2.117 7) A C-band radar with an antenna 1.8 m in radius transmits 60 kW at a frequency of 6000 MHz. If the minimum detectable power is 0.26 mW, for a target cross section of 5 m 2 , calculate the maximum range in nautical miles and the signal power density at half this range. Assume unity efficiency and that the effective area of the antenna is 70% of the actual area. SOLUTION: 8) The magnetic vector potential at point P(r, θ, φ) due to a small antenna located at the origin is given by where r 2 = x 2 + y 2 + z 2 . Find E(r, θ, φ, t) and H(r, θ, φ, t) at the far field. SOLUTION: Using Vector transformation, ...