1. For the coaxial cable of Example 6.9 employing air dielectric, find the ratio of the outer to the inner radii for which the characteristic impedance of the cable is 75 Ω.
2. Using the general solutions for the complex line voltage and current on a lossless line given by (7.9a) and (7.9b), respectively, obtain the particular solutions for the complex voltage and current on an open-circuited line. Then find the input impedance of an open-circuited line of length l.