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.
Examples A few examples of aerials made of cage sections are:
Quadrant antenna A quadrant antenna is an omnidirectional shortwave transmitting antenna shaped like a rhombus or lozenge, made from two identical, opposing L-shaped cage dipoles lying in the same horizontal plane, aligned with their 'elbows' pointing in opposite directions
Curtain antenna A curtain array antenna is a directional shortwave transmitting antenna made of several parallel-aligned dipoles, each made of cage sections.
History In 1921, an amateur radio operator tried to win a $500 prize with his cage aerial.
References
See also
(PDF) Design and Analysis of Cross Cage Dipole Antenna