Signal transmission in the RF and microwave fields largely relies on transmission cables. Coaxial cables and waveguides are widely used to transmit microwave RF energy. These two types of transmission cables differ significantly in size, material, and transmission characteristics. Waveguides to coaxial adapters are necessary to interconnect these two types of transmission. Coaxial-waveguide converters play an indispensable role in various radar systems, precision guidance systems, and test equipment.