Numerical Sheet3

NUMERICAL SHEET 3 PROPAGATION OF EM WAVES 1. A wave travelling in free space undergoes refraction after entering a denser medium such that the original 30° angle of incidence at the boundary between the 2 medium is changed to 20°. What is the velocity of EM waves in the second medium? 2. In a typical MF broadcasting situation, a 150m antenna, transmitting at 1.2MHz has an antenna current of 8A. What voltage is measured by a receiving antenna 40 km away, with a height of 2 m? 3. Two points on earth are 1500 km apart and are to communicate by means of HF. Given that this is to be single-hop transmission, the critical frequency at that time is 7MHz and conditions are idealized, calculate the MUF for those 2 pts if the height of the ionospheric layer is 300km. 4. The wavelength of an x-directed plane wave in a lossless medium is 0.25m and the velocity of propagation is 1.5x10^10 cm/s. The wave has z-directed electric field with an amplitude equal to 10V/m. Find the frequency and permittivity of the medium. The medium has U/Uo. (600MHz, 4) 5. If H field is givenby H(z,t) = 48 cos(10^8t+40z)ay A/m, identify the amplitude, frequency and the phase constant. Find the wavelength. 6. Calculate the open circuit voltage in λ/2 dipole when 10W at 150MHz is radiated from another λ/2 dipole is 50km distant. The antennas are positioned for optimum transmission and reception.(maximum gain = 1.64) (282µV) 7. Calculate the maximum range for a tropospheric transmission for which the antenna heights are 100ft and 60ft. (25.1miles)