Application: >J2 dipole. A half-wavelength antenna is made of copper wire with conductivity a = 5.7 x 107 Sim. The antenna is 3-mm thick and 1.5-m long.
(a) Calculate the impedance of the antenna and its efficiency when radiating in free space.
(h) In an attempt to reduce the impedance and increase efficiency, the antenna is made ofa copper tube, 12-mm in diameter. What is the efficiency of the antenna? Assume current flows entirely within one skin depth, on the surface of the tube.