From its almost accidental origins, the axial mode helix antenna has gone from a young professor’s laboratory curiosity to one of the most widely used antennas for UHF and microwave communications. With the explosive growth of satellite-based services, the ability to receive or transmit a tight beam of circularly polarized radiation while minimizing unwanted radiation is imperative to maintaining good communication. The axial-mode helical antenna provides a high performance and robust antenna platform both in space as well as on the ground.