Researchers have demonstrated a technique that uses a laser to produce a plasma beam antenna capable of transmitting radio waves. Credit: Prya Darshni, NC State University
Researchers have demonstrated a technique that uses a laser to produce a plasma beam antenna capable of transmitting radio waves.
The study, published in IEEE Journal of Microwaves, examined whether a laser could generate plasma antennas at whatever length is needed. Antenna length controls the frequencies at which radio waves can be transmitted and received, and adjusting it to sweep a range of frequencies is difficult in applications such as space exploration technologies.
By firing a laser beam of a specific power and diameter, the researchers are able to ionize a thin beam of air, creating a defined shaft of plasma called a plasma filament. But in order to make the plasma antenna a practical tool, the researchers also needed to develop a way to connect the antenna to radio technology to transmit a radio signal.
To solve that problem, the researchers created and demonstrated a contactless antenna-feed, which consists of a metal ring that serves as a capacitor. The laser passes through the ring, creating a plasma filament that is surrounded by the capacitor. By generating an electromagnetic field with the capacitor, the researchers were able to interact with the plasma beam without touching it.
In the long term, the technology holds promise for use in a variety of applications. Satellites and space exploration technologies are one potential area of interest, because payload and the ability to scan across a wide range of frequencies are both important considerations.
“This is the first step, but it is a big step—it is the first time anyone has ever demonstrated that plasma-filament antennas can work,” said corresponding author Prya Darshni, a Ph.D. student at North Carolina State University. “Now that we’ve shown it is possible, we can begin improving its performance.”
Data from N.C. State University