A cage antenna (British cage aerial) is a radio antenna where a conventional design has been augmented by replacing a single long conductor with several parallel wires, connected at their ends, and held in position by ring spacers or support struts mounted on a central mast (if any). The "cage" is either mounted around a central mast (either conducting or non-conducting) or suspended from overhead wires.

Purpose

Examples of this are the quadrant antenna, a steeply omnidirectional shortwave transmitting antenna in the form of an L-dipole consisting of two identical cage traps, and the curtain antenna (a directional shortwave transmitting antenna) with several folding dipoles made of cage traps.

History

In 1921, a amateur radio operator try to win a $500.00 prize with his cage aerial.