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Unformatted text preview: Assignment #9 1. Design a parabolic antenna for an antenna gain of 6000 at a frequency 6000 MHz. Calculate the beam width between halfpower points of this antenna. Assuming 90% antenna efficiency, calculate the power received if the incoming signals have a power density of 1µ W/m2. 2. A paraboloid reflector with diameter 50 meters is used at 1500 MHz. Calculate the beam width and power gain. 3. For a rectangular aperture(a,b) in xyplane is linearly polarised in y direction and the aperture excitation has a uniform phase and a triangular amplitude distribution F ( x) = 1 − 2 x , x ≤a a Find (i)Pattern function (ii)half power beam width (iii)location of first nulls(cheng:11.34) Assignment 8
November 12, 2009 1. The normalized radiation pattern of uniformly illuminated Circular aperture is given by
E (φ) = where J1 is rst order bessel functions D = diameter of aperture λ= free space wavelength φ= angle with respect to normal of the aperture Find (a) rst nulls of radiation pattern (b) HPBW (c) Directivity 2. Four 900 corner reector antennas are arranged in line as a broad side array. The corner edges are parallel and side by side as shown in g. The spacing between the corners is λ. The driven antenna in each corner is λ/2 element spaced 0.4λ from the corner. All antennas are energized in phase and have equal current amplitude. Assuming Radiation intensity of a corner reector is given by
E (φ) = 2EHW I1 [cos(Sr cos(φ) − cos(Sr sin(φ)))] 2λ J1 [(πD/λ)sinφ] πD sinφ where I1 = current in the element EHW =Electric eld due to half wave dipole (a) Find the gain of the array over a single λ/2 dipole (b) Plot the radiation pattern of the array (c) Half power beam width 3. A circular parabolic dish antenna has an eective apperture of 100m2 . If one 300 sector of parabola is removed, nd the new eective aperture. The rest of the antenna including feed, is unchanged. 1 ...
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This note was uploaded on 09/12/2010 for the course EE EE645 taught by Professor Ujin during the Spring '10 term at YTI Career Institute.
 Spring '10
 Ujin
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