Evaluation of the effectiveness of electromagnetic field shielding to protect confidential information from unauthorized access

The shielding the electromagnetic field from the personal computer is essential to prevent unauthorized access to confidential information. The study conducted an experimental study of the effectiveness of shielding electromagnetic fields in the frequency range from 1 kHz to 20 kHz using metal plates. The article describes an experimental installation that is equipped with the broadband low-frequency amplifier, the emitter and the receiving sensor. The developed installation made it possible to evaluate the effectiveness of shielding electromagnetic fields in the studied frequency range. In experimental studies, the output voltage was measured depending on the frequency of the signal. In accordance with the developed research methodology, the electromagnetic signal was created in the virtual audio frequency signal generator with amplitude of 50 mV. Next, it was fed to the input of the low-frequency broadband amplifier, which had the uniform amplitude frequency response in the range of 50 Hz – 20 kHz. The studied component of the electromagnetic field was recorded using a receiving sensor and transmitted to the input of an oscilloscope. The generated electromagnetic signal was passed through the metal plate, which was placed between the radiation source and the receiving device. The experiment used screen materials with the thickness of 0.5 mm to 1 mm, and also evaluated their effect on the absorption and reflection of the electromagnetic field in the studied low-frequency range. Sheet metals with the size of 50x80 mm were used as samples. These screens were made of aluminum with the thickness of 1 mm and 0.5 mm, copper and brass with the thickness of 0.4 mm, as well as steel cuts from the body of the computer system unit with the thickness of 1 mm. The measurement results confirmed that the material and thickness of the plate affect the shielding efficiency. Thus, aluminum with the thickness of 1 mm provides attenuation up to 26.5 dB at the frequency of 20 kHz. The analysis showed that copper plates are the most effective for shielding at higher frequencies, and steel plates are the most effective for shielding at low frequencies. Brass provides the lowest degree of protection among the studied materials. The obtained data emphasize the importance of reasonable selection of materials and thickness of electrically conductive screens to protect potentially vulnerable frequency components of the electromagnetic field of personal computers. Electromagnetic shielding can be an effective way to increase the level of information security and protect confidential information from unauthorized access through electromagnetic hacking.