In general, all communication systems require effective guiding and efficient processing elements. At UHF and above the conventional transmission, generation, reception and measuring equipment become either grossly inefficient or altogether defunct. At microwave range, these elements have to be more sophisticated and perfect. The requirement becomes more and more stringent with the increase of frequency. This is due to the fact that with the increase of frequency, the power-handling capability of components declines and the wave propagation becomes susceptible to the physical dimensions of components. The shapes and roughness of surfaces of components also significantly affect the propagating waves.