A Broadband Electromagnetic Absorber for Mobile Telecommunication Combo Antennas

Mobile network operators (MNOs) have to sustain the interworking of different generations of mobile technologies in different frequency bands. On the other hand, electromagnetic (EM) pollution, which is caused mainly by the mobile devices and mobile network base stations, also raises public health concerns. Thus, MNOs use combo antennas, which encapsulate multiple antenna rods in a single radome. In this study, the authors propose a broadband electromagnetic absorber for the mobile network base station (BS) combo antennas. They have merged the multi-layer Jaumann absorber (JA) and Salisbury screen principles along with the merits of off-the-shelf micrometric and millimetric graphite and nanometric carbon black. Advanced silver and nickel coated nanometric cenospheres were also used to decrease the absorber thickness and to improve EM scattering and absorption. And finally, silver fabric was used as the salisbury screen with novel perpendicular threads into the absorber body as heat sink. After the laboratory tests, the absorber has also been tested in the field. The application of the absorber has reduced the unwanted radio frequency (RF) signal around 18 dB in the tested frequency range without any network affecting disturbances or without any noticeable antenna pattern deformation with only a thickness of ninety millimeters. Such an absorber may also help containing the unwanted spread of electromagnetic waves from BS antennas; and, in return, decrease the overall mobile network RF noise and electromagnetic pollution both in uplink and downlink frequency bands