RF Energy Absorption in Human Bodies Due to Wearable Antennas in the 2.4 GHz Frequency Band

Human exposure to electromagnetic fields produced by two wearable antennas operating in the 2.4 GHz frequency band was assessed by computational tools. Both antennas were designed to be attached to the skin, but they were intended for different applications. The first antenna was designed for off-body applications, i.e. to communicate with a device placed outside the body, while the second antenna model was optimized to communicate with a device located inside the body. The power absorption in human tissues was determined at several locations of adult male and female body models. The maximum specific absorption rate (SAR) value obtained with the off-body antenna was found on the torso of the woman model and was equal to 0.037 W/kg at 2.45 GHz. SAR levels increased significantly for the antenna transmitting inside the body. In this case, SAR values ranged between 0.23 and 0.45 W/kg at the same body location. The power absorbed in different body tissues and total power absorbed in the body were also calculated; the maximum total power absorbed was equal to 5.2 mW for an antenna input power equal to 10 mW.

Measurements and Analysis of Temporal and Spatial Variability of WiFi Exposure Levels in the 2.4 GHz Frequency Band

This paper presents an evaluation of the WiFi exposure levels inside the university in the 2.4 GHz frequency band. The selected environment is the typical scenario where WiFi exposure concerns have increased in the last years, since a Wireless Local Area Network is deployed close to the users. Measurements of 1 h and 24 h of duration were performed to assess the temporal and spatial variability of the signal. Two instruments were employed, a spectrum analyzer appropriate configured for recording accurate and realistic samples and an exposimeter. A detailed description of the equipment, the measurement procedure and data analysis is provided in order to allow the reproducibility of these types of measurements. Finally, a comparison of the WiFi levels obtained by other authors is presented, concluding that all these methods are useful for determining WiFi exposure distribution, but if more accurate results are required, professional equipment appropriately configured should be used.

Threats and Limitations of Terrestrial Broadcast Attacks

The DVB standard does not mandate the use of authentication and integrity protection for transport streams. This allows malicious third parties to replace legitimate broadcasts by overpowering terrestrial transmissions. The rogue signal can then deliver a malicious broadcast stream to exploit security vulnerabilities on Smart TVs (STVs) in range. We implemented a proof-of-concept attack based on a malicious Hybrid Broadcast Broadband TV app, able to acquire permanent system-level access to an STV over the air, in less than 10 s. These attacks, however, are severely limited in range due to required co-channel protection ratios (CCPRs), which is in direct contradiction to previous publications. We present evidence for these limitations in form of laboratory experiments, extensive simulations, and field measurements. To this end, we developed an automated, low-cost method for CCPR determination, as well as a method for non-disruptive attack range measurements based on a gap filler and the resulting channel impulse response.