Why do most amateur radio antenna systems use coaxial cable, rather than other types of transmission line?

Coaxial cable is highly favoured in amateur radio because its shielded design makes it exceptionally versatile. The electromagnetic field is contained entirely within the cable between the center conductor and the outer shield. This means it can be routed through walls, buried underground, or run alongside metal masts without interacting with its surroundings. In contrast, alternatives like ladder line or open-wire feedline are unshielded. They must be carefully routed and kept away from metal objects and structures to avoid detuning the antenna system. While coax is incredibly convenient, it is important to note that distractors like 'less loss' or 'less expensive' are incorrect. Open-wire line actually has significantly lower loss and is often cheaper than high-quality coaxial cable.