RF, or radio frequency weapons, also known as directed-energy weapons, use electromagnetic energy on specific frequencies to disable electronic systems. The principle is similar to that of high-power microwave (HPM) weapons, only HPM systems tend to be much more sophisticated, and are thus, more likely to be in the control of superpowers or near-superpowers. RF weapons, by contrast, are simple and low-voltage enough that they could be deployed by smaller, less technologically enhanced forces.
The range of frequencies for waves in the electromagnetic spectrum is from approximately 102 Hz to more than 1025 Hz —in other words, from about 100 cycles per second to about 10 trillion trillion.
From the lowest frequencies to about 1010 Hertz is the range of long-wave radio, shortwave radio, and microwaves. These carry broadcast radio, television, mobile phone communications, radar, and even highly specific forms of transmission such as those of baby monitors or garage-door openers.
Because of regulation by the Federal Communications Commission (FCC), AM or amplitude modulation broadcasts take place across a frequency range from 535 kHz (kilohertz, or 1,000 Hertz) to 1.7 MHz (megahertz, or 1,000,000 Hertz). The FCC has assigned the range of 5.9 to 26.1 MHz to shortwave radio, and 26.96 to 27.41 MHz to citizens’ band (CB) radio. Above these are microwave regions assigned to very high frequency (VHF) television stations 2 through 6, then FM (frequency modulation) radio, which occupies the range from 88 to 108 MHz. Higher still are VHF channels 7 to 13, ultra-high frequency (UHF) television broadcasts, and so on. At the highest microwave ranges—around 1010 Hz—are transmissions from spacecraft.
FCC regulation is necessary to maintain security, privacy, and safety on the airwaves. If a broadcaster or receiver strays outside of its assigned range, it can intercept private communications, or potentially disrupt highly sensitive transmissions. Among the most sensitive from a safety perspective, are the communications between an aircraft cockpit and the control tower, which could result in serious consequences if disrupted even for a few seconds.
High-power microwave weaponry is of such voltage and intensity that it can actually shut off the computer systems of an aircraft long enough that a pilot could conceivably be unable to right the craft, causing a crash.
With an RF weapon, the intensity of the signal is smaller, but if properly directed, it could potentially disrupt aircraft communication systems long enough to bring down the craft. It could cause the computers to reset, or disrupt safety sensors, navigation systems, data recorders, or control systems. Enough errors in these sensitive flight components, particularly in the highly computerized aircraft of today, might be enough to force a plane out of the sky.
Concerns over RF interference dictate the prohibition against cell phone, radio, or even laptop computer operation aboard a plane from the time of preparation for takeoff until after it lands. Such relatively weak and innocuous systems could interfere with vital flight communications; one can easily imagine the harm that could be done by terrorists operating a directed and more powerful system with malicious intent. Adding to the dangers of RF weaponry is the fact that it could potentially be operated
from the ground, allowing the terrorist to attack and seek cover in the process, and rendering the sacrifice of the terrorist’s life unnecessary. Furthermore, RF weaponry,
like most means of electromagnetic warfare, is “clean,” meaning that, unlike ordinary ballistic weaponry, it is almost untraceable.