Electrical properties of ferrite absorber in the frequency range from 15 GHz to 45 GHz

All medical devices should have electromagnetic interference with an electric field strength of 9 V/m to 28 V/m, depending on the frequency range. In this case, these values are too low in relation to the reference levels defined in Recommendation 1999/519/EC, expressed as limits of the intensity of the electric component of the E-field, which are as high as 61 V/m. The presence of electric field strengths higher than 9-28 V/m in the environment may cause negative effects on the operation of medical devices. The negative effects of a medical device are obvious and include damage to human health or even death. This article presents the possibilities of using ferrite absorption material for shielding rooms with medical devices in order to additionally protect them against the limits of the electric component of the E field, which is up to 61 V/m. These values may appear in connection with the currently launched 5G system operating in the high-band frequency range, i.e. 28 GHz and 38 GHz. They may have negative effects on the operation of medical devices. Design/methodology/approach The possibilities of using ferrite absorption material for shielding rooms with medical devices were determined based on the results of measurements of the electrical properties of the ferrite material performed using two methods: the reflection method and the free space method. The article determined the complex electrical permittivity and complex magnetic permeability of a ferrite plate based on measurements of the reflection coefficient and the transmission (attenuation) coefficient. The presented calculation and measurement results were used to show the properties of the ferrite material in the frequency range from 15 GHz to 45 GHz and to show the possibility of using it for shielding rooms as a material absorbing electromagnetic waves in this frequency range. Research limitations/implications The major limitations of the measurement methods used are coaxial probes and measurement antennas, characterised by a limited operating bandwidth. The free space method uses test antennas with a limited operating band of 15-45 GHz. For this reason, the research results were limited to this frequency range. Practical implications The presence of electric field strengths higher than 28 V/m in the environment may cause negative effects on the operation of medical devices. The negative effects of a medical device malfunction are obvious and include damage to human health. The attenuation of the ferrite absorber in the frequency range 15-45 GHz is 16-12 dB, respectively. Therefore, using it as a shielding material in this frequency range will attenuate the electric field intensity from 61 V/m to 10-15 V/m. Since medical devices should be immune to electromagnetic disturbances with an electric field strength of 28 V/m, electric field strengths of 10-15 V/m should not negatively affect their functionality. Originality/value Ferrite absorbers are used in the band from approx. 10 MHz to approx. 1000 MHz. Most often, they are intended for use in anechoic chambers. The publications only provide information on the properties of the ferrite absorber in the frequency range of up to 1 GHz. Due to its properties in the frequency range up to 1 GHz, it was decided to investigate the properties of the ferrite material in the high-frequency range of the 5G system bands, i.e., 28 GHz and 38 GHz, to show the properties of this material and the possibility of using it in these frequency ranges as a shielding material. The properties of the ferrite absorber in the presented frequency band are not published.