C. K. Tang

Electromagnetic Interference Immunity Testing of Medical Equipment to Second- and Third-Generation Mobile Phones

There has been concern regarding the effect of electromagnetic interference (EMI) on medical equipment from portable wireless communication devices in hospitals in Hong Kong. The latest third-generation (3G) mobile communication system was fully implemented in 2004. As a result, an investigation to examine the EMI issues surrounding medical equipment, due to interference from communication devices, including GSM900, PCS1800, and 3G digital mobile phones, has been carried out. A statistical analysis has shown that the cumulative distribution function of base station signals within the hospitals environment follows the Weibull distribution for all three mobile phone systems in Hong Kong and that the percentage of failed medical equipment increases with a correlation of an increase in the radiated power level of the mobile phone. This is a direct result of a weakening in base station signals. The EMI effect from 3G mobile phones is also found to be four to eight times lower than that of the GSM900 and PCS1800, in locations inside the hospitals with weak base station signal strength, such as a basement or in operation theaters.

Electromagnetic Field Radiation of Mobile Phone Inside Metallic Enclosure

A numerical study on the electromagnetic (EM) Held radiation of mobile phone inside metallic enclosure, for human safety aspect, is presented in this paper. The study on the effects of number of human bodies and their positions inside the metallic enclosure on the induced E-field was carried out. Results have shown that the E-field induced on the human head of mobile phone user is not sensitive to the loadings of human bodies inside the metallic enclosure. However, the E-field induced away from the mobile phone user that contributes to the E-field exposure of other people nearby is significantly changed for different human capacities inside the metallic enclosure. Results have also indicated that the E-field induced on the human head of mobile phone user would be increased by 34% when people using mobile phone in proximity to the conducting wall of metallic enclosure.

Antenna performance of mobile phone and corresponding human exposure inside fully and partially enclosed metallic elevator

The effects of using mobile phone inside both fully and partially enclosed metallic elevators on the antenna performance and the human exposure have been studied by using FDTD numerical method. It has been found that the antenna performance is degraded in all the enclosed metallic elevators studied due to the low radiation efficiency. Results have also shown that, for the human exposure, the electric field strength and the peak SAR of mobile phone user in the fully enclosed metallic elevator is the largest due to the resonance effect.

Study of using fractional phantom head model on SAR evaluation in mobile antenna design

This paper studies the use of fractional phantom head model on Specific Absorption Rate (SAR) evaluation in mobile antenna design. The SAR value of a duel-band model patch antenna designed with different length and width of ground plane configurations is investigated. It is found that the fractional phantom head model can be used for efficient SAR evaluation in practical mobile antenna design.

On-site EMC assessment of IT equipment in financial data centre of Hong Kong

In this paper, an on-site EMC assessment of information technology (IT) equipment installed in a typical financial data centre in Hong Kong is presented. The background electromagnetic (EM) environment assessment of the data centre has been carried out before and after the completion of the IT equipment installation. The assessment covered a frequency band ranging from 30MHz to 11GHz, which includes most of the wireless communication systems, such as GSM900, PCS1800, 3G and WLAN. Results have shown that the EM level is well below the recommended limit in both pre- and post-installation of the IT equipment. As the IT equipment requires an extremely high reliability and accuracy for processing vast amount of electronic financial transactions in the data centre, it is recommended that the annuity EMC assessment shall be performed every year.

Assessment of radiated immunity of C-band satellite TV receiving station in Hong Kong local environment due to UWB interference

In this paper, the radiated immunity of C-band satellite TV receiving station to UWB interference in the Hong Kong local environment has been investigated. Results have indicated that the UWB interference, including degradation in the picture quality and in the BER after correction, cannot be identified for any separation distance large than 12 m, even if the e.i.r.p of UWB device is at -41.37dBm/MHz. However, the interference power received at the C-band antenna could be larger in some cases, such as operation of multiple UWB devices with aggregate effect, and when the UWB device is located within the main beam pattern or at different angles.

Study of using fractional phantom head model on SAR evaluation of external helical mobile antenna

In this paper, a fractional head modeling on the SAR evaluation of external helical antennas is studied. In the FDTD simulation model, it mainly consists of spherical phantom head and helical antenna installed on mobile phone casing. Both the return loss and the SAR value due to the fractional head modeling are investigated. In order to study the effectiveness of the fractional head model for SAR evaluation, the comparison on the computational usage and the simulation time is also analyzed.

EMC Assessment on Power Frequency Radiation in High-Rise Building

Substations, electrical rooms and high current busway risers are placed in secured vaults, and commonly located within the buildings, where a high level of magnetic field radiation is generated; this situation has raise the concern on human safety issue particularly for high-rise buildings. In this paper, an assessment of magnetic field radiations at power frequency inside a high-rise building in Hong Kong is described, and the measured magnetic field is referenced to the safety limits stated in ICNIRP guideline