Plasma antenna
Plasma replaces metal in antennas for stealth and reconfigurability.
A plasma antenna is a radio antenna still under development that uses plasma in place of the metal parts found in conventional antennas. It can both transmit and receive signals. While practical versions have only emerged recently, the idea itself is older; J. Hettinger received a patent for such an antenna in 1919. Early working models used discharge tubes to hold the plasma and are called ionized gas plasma antennas. These can be switched on and off, making them useful for stealth and resistant to electronic warfare and cyber attacks. They can also be nested, with higher-frequency plasma antennas placed inside lower-frequency ones. Higher-frequency arrays can send and receive signals through lower-frequency arrays, allowing co-location and stacking. This design can reduce or eliminate co-site interference. Smart versions use plasma physics to shape and steer beams without phased arrays. Satellite signals can be steered or focused using banks of plasma tubes in reflective or refractive modes, creating unique ionized gas satellite plasma antennas. At higher frequencies, these antennas produce less thermal noise than metal ones. Solid state plasma antennas, also called plasma silicon antennas, are also in development and can be made using standard silicon chip fabrication. They offer steerable directional functionality and are candidates for WiGig, the planned Wi-Fi upgrade, as well as other uses like lowering the cost of vehicle-mounted radar collision avoidance systems.
In an ionized gas plasma antenna, a gas is ionized to create plasma. Unlike gases, plasma has very high electrical conductivity, so radio frequency signals can travel through it, allowing it to act as a driven element (like a dipole antenna) to radiate or receive radio waves. Alternatively, the plasma can serve as a reflector or lens to guide and focus radio waves from another source. Solid-state antennas differ by creating plasma from electrons generated by activating thousands of diodes on a silicon chip.
Plasma antennas offer several advantages over metal ones. Once the plasma generator is turned off, the plasma returns to a non-conductive gas, making it effectively invisible to radar. They can be dynamically tuned and reconfigured for frequency, direction, bandwidth, gain, and beamwidth, replacing the need for multiple antennas. They are resistant to electronic warfare.
- Patent granted
- 1919
- Patent holder
- J. Hettinger
- Patent number
- US1309031A
Lore & Background
The idea of a plasma antenna dates to a 1919 patent granted to J. Hettinger. Early practical implementations used discharge tubes to contain ionized gas, creating ionized gas plasma antennas. These can be turned on and off, making them effectively invisible to radar when deactivated. They are resistant to electronic warfare and cyber attacks. Ionized gas plasma antennas can be nested, with higher frequency antennas placed inside lower frequency ones, allowing arrays to be stacked and co-located while reducing co-site interference. Smart versions use plasma physics to shape and steer beams without phased arrays. Satellite signals can be steered or focused using banks of plasma tubes in reflective or refractive modes. Solid state plasma antennas, which generate plasma from electrons produced by activating thousands of diodes on a silicon chip, are now in development for applications such as WiGig and vehicle-mounted radar collision avoidance systems.
Reader's Guide
Plasma antennas represent a shift from fixed metal elements to reconfigurable plasma structures. Their ability to be turned on and off provides stealth advantages, as the antenna becomes non-conductive and radar-invisible when deactivated. They can be dynamically tuned and reconfigured for frequency, direction, bandwidth, gain, and beamwidth, potentially replacing multiple antennas. Their resistance to electronic warfare and cyber attacks adds to their appeal for military and secure communications. At satellite frequencies, ionized gas plasma antennas exhibit less thermal noise than corresponding metal antennas, enabling faster data rates. The nesting capability allows co-location of antennas operating at different frequencies, reducing co-site interference. Solid state versions, fabricated with standard silicon chip techniques, promise low-cost integration into consumer electronics like WiGig and automotive radar. The technology is still in development, but its potential for reconfigurability, stealth, and reduced interference marks a notable departure from conventional antenna design.
Did You Know?
- A patent for a plasma antenna was granted to J. Hettinger in 1919.
- Higher frequency ionized gas plasma antenna arrays can transmit and receive through lower frequency ionized gas plasma antenna arrays.
- Solid state plasma antennas can be manufactured using standard silicon chip fabrication techniques.
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