RF Systems & Havana Syndrome | 14th November 2026
Radar uses electromagnetic radio waves to detect objects, measure distances and track movement. However, the same physical principles involved in radar transmission are also relevant to scientific research into how radio-frequency (RF) energy interacts with the human body, including the microwave auditory effect.
Radar stands for Radio Detection and Ranging. It operates by transmitting electromagnetic energy, often in short pulses, towards an object or area. These radio waves travel at approximately the speed of light, reaching 299,792 kilometres per second in a vacuum and almost the same speed through air.
When electromagnetic waves encounter an object, some energy may be reflected, scattered, transmitted or absorbed. Radar receivers analyse returning signals to determine an object's distance, direction and movement. For example, a radar pulse taking one millisecond to travel to an object and return indicates a distance of approximately 150 kilometres.
In radar terminology, illumination describes the exposure of an object or area to transmitted RF energy.
Radar systems can operate using short electromagnetic pulses or continuous transmissions. Pulsed radar sends bursts of energy separated by intervals, while continuous-wave radar transmits without regular interruptions. Frequency-modulated systems vary their transmitted frequency, and passive radar detects signals from existing transmitters rather than generating its own.
These distinctions are important because the biological effects of electromagnetic exposure depend partly on how the energy is delivered.
When pulsed microwave radiation reaches biological tissue, a small proportion of the electromagnetic energy may be absorbed, producing extremely rapid, localised temperature changes. These changes can cause slight thermoelastic expansion, generating mechanical pressure waves that propagate through the tissue.
Under suitable conditions, these pressure waves stimulate the cochlea within the inner ear, where mechanical vibrations are converted into electrical signals. These signals travel through the auditory nerve and are processed by the brain, producing the perception of sound without conventional sound waves entering through the outer ear.
The resulting sensations may include clicks, buzzing or other sounds. When suitable modulation or encoding strategies are applied to pulsed microwave transmissions, the resulting acoustic patterns can convey information. Historical experiments explored Morse code and speech, demonstrating that microwave-induced auditory perception is not limited to isolated clicks.
American neuroscientist Allan H. Frey investigated the phenomenon in the early 1960s. Subsequent experiments by Joseph C. Sharp and Mark Grove in 1973 demonstrated recognition of spoken words through microwave-induced auditory sensations, while James C. Lin and other researchers further investigated the underlying thermoelastic mechanisms.
In 1975, psychologist Don R. Justesen described experiments involving microwave transmissions modulated with recorded speech. These historical reports are significant.
More recently, research published in October 2026 by Cody Donald Baker and colleagues examined electromagnetically generated thermoacoustic pressure waves within a computational model of the human head. The study investigated how microwave pulse characteristics and anatomical structures influence the development and propagation of pressure waves.
The research builds upon the established thermoelastic explanation of the microwave auditory effect. However, it involved mathematical modelling rather than new human exposure experiments.
The distinction between RF illumination, energy absorption and auditory perception remains important. Exposure to electromagnetic radiation does not automatically produce audible sensations. The outcome depends on frequency, pulse duration, energy deposition, modulation and the response of the auditory system.
The microwave auditory effect demonstrates that appropriately pulsed electromagnetic energy can generate mechanical pressure waves within biological tissue, stimulate the auditory system and produce neural electrical activity interpreted by the brain as sound.
Historical experiments involving encoded signals, together with modern computational research, continue to inform scientific understanding of this interaction between electromagnetic radiation, acoustic pressure waves and human perception.