Researchers at North Carolina State University have created an experimental antenna system that generates a narrow plasma beam using a laser, resembling a lightsaber in appearance. The technology transmits radio waves through ionized air rather than traditional metal structures, offering potential advantages for applications requiring flexible, adaptable antenna systems.
Conventional antennas depend heavily on their physical dimensions to determine which radio frequencies they can transmit or receive. Adjusting antenna length to operate at different frequencies typically requires moving mechanical components or complicated engineering solutions, which presents particular challenges for space applications where equipment must remain compact, lightweight, and reliable. The NC State team explored whether a laser could provide a simpler alternative by creating an antenna directly in the surrounding air, eliminating the need for physical extension or retraction of metal structures.
The system works by directing a laser through the air and carefully controlling its power and beam diameter to ionize a narrow region, stripping electrons from atoms and molecules to create plasma. This concentrated channel of ionized air, called a plasma filament, serves as the antenna foundation. To transmit radio waves, the researchers developed a contactless antenna feed using a metal ring that functions as a capacitor. The laser passes through the ring’s center while the surrounding electromagnetic field transfers energy to the plasma without physical contact. When a radio frequency generator sends a signal, the electromagnetic field interacts with the plasma filament to transmit radio waves. The team successfully demonstrated transmission at 30 megahertz in the very high frequency radio band.
A key advantage of this technology is its adjustability. Since the antenna is created by laser rather than built from fixed metal structures, its dimensions can be modified by changing laser settings. Researchers can control the plasma filament’s length and angle by adjusting laser parameters and steering the beam direction, potentially allowing antenna characteristics to sweep across multiple frequencies and target specific signal directions without requiring mechanical moving parts.
Although transmission has been demonstrated, the antenna’s ability to receive signals and operate across a broader frequency range requires further testing. The researchers view satellites and space exploration as particularly promising applications, where the technology could enable spacecraft to create and adjust antennas without carrying complex mechanical deployment systems, potentially reducing weight and launching constraints.
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