1) A transmitting antenna has an effective height 2/pi times the physical length. This carries a current of 1600 A at the base and operates at a frequency of 20 KHz. If the physical length of the antenna is 200 meters and antenna, efficiency is 10%. Determine:
a) Electric field intensity at 350Km.
b) Radiation Resistance
c) Power radiated
d) Power input in the antenna
2) A plane electromagnetic wave with a frequency of 10 MHz has an average pointing vector of 1W/m2with relative permeability 2 and relative permittivity 3, find out:
a) The velocity of propagation
b) The wavelength
c) The impedance of the medium
d) The r.m.s electric field ‘E’.
3) Two identical point sources separated by the distance ‘d’, each source with a field pattern given by E0=E1Sinθ. If d=λ/2 and the phase angle α=0, deduce an expression for total field. If medium is lossless pattern. Plot the pattern.
4) Develop the four-element broadside array of λ/2 spacing between the components. The pattern is to be optimum with the side lobe level 19.1dB down the main lobe maximum.
5) Discuss how a loop antenna is used for direction finding of incoming EM waves. Deduce an expression for voltage induced in the loop. How can the sense of ambiguity be resolved?