Why is it called coaxial optical cable

A coaxial cable, often referred to as "coax," is designed with a central conductor that carries the electrical signal, surrounded by a dielectric insulating layer, a metallic shield, and an outer protective jacket. The term "coaxial" comes from the fact that the inner conductor and the outer shield are aligned along the same axis, forming a concentric structure . This alignment is crucial because it confines the electromagnetic field carrying the signal to the space between the conductor and the shield, which minimizes signal loss and prevents interference from external electromagnetic sources . The coaxial design differs from other cable types, such as twisted pair or parallel cables, because the precise spacing between the conductor and shield is maintained by the dielectric, ensuring consistent impedance and efficient high-frequency signal transmission . The metallic shield, often made of braided copper or aluminum foil, acts as a barrier against electromagnetic interference (EMI), while the outer jacket protects the cable from physical damage and environmental factors . This structural configuration allows coaxial cables to transmit high-frequency signals over long distances with minimal loss, making them ideal for applications like cable television, broadband internet, radio communications, and other telecommunications systems . The shared axis of the conductor and shield is the defining feature that gives the cable its name and ensures its effectiveness in reducing interference and maintaining signal integrity.