4. Assume an antenna has a radiation pattern given by F(0.4)= 1: for 60°<< 120° and -180° << 180°, 10: elsewhere. (a.) Sketch the polar radiation pattern F(0,0) for 0 <0, 90°, (b.) Sketch the polar radiation pattern F(90°.), (c.) Calculate the beam efficiency about 80° <<100° and -180° << 180°, (d.) Plot the beam efficiency about You may ignore the azimuth angle ø. = 90° as a function of 80, that is, for 90° ± 80 and -45° < 80 < 45°.