Lin Biao Wang

Ultrathin and Flexible Screen-Printed Metasurfaces for EMI Shielding Applications

An ultrathin, lightweight, and flexible metasurface for band-stop electromagnetic interference (EMI) shielding purpose has been designed and fabricated using screen-printing technology. Using a 1.8 GHz band-stop EMI shield as a design example, a prototype of a screen-printed metasurface has been validated using measured and numerically computed results. Hence, screen printing can be an attractive option for flexible and lightweight shields that can be easily applied on the walls and windows of a room to block specific wireless communication band so as to protect critical electronics instruments from possible EMI.

Investigation of radiated emissions in power line communication networks

Experimental studies are carried out to investigate the effectiveness of solving the electromagnetic interference (EMI) problem in power line communication (PLC) networks. A test bed is designed to study the effectiveness of the method. Measurements are carried out in a semi-anechoic chamber using a clamp-on current probe, a rod antenna and a loop antenna to compare the conducted and radiated emissions for the various cases. It is well known that the dominant mode of radiation is common mode (CM). The experimental results show that both the conducted and radiated emissions can be reduced by 15dB. This is achieved by increasing the impedance between the noise source and the power line network across the alternative noise path.

Tri-band frequency selective band-stop shield using screen printing technique

A tri-band frequency selective band-stop EMI shield is designed using various concentric rings with each ring resonating at the specific desired frequency. The shield is fabricated using roll-by-roll screen-printing process, making it suitable for large surface architectural shielding applications. The design is designed using full-wave simulation tool and the performance is validated experimentally.

Near-field to far-field prediction for high-speed board using an empirical approach

This paper describes a methodology to predict far-field (FF) emissions from a high-speed board based on the fields measured in the near-field (NF) region. The NF to FF transformation is based upon an empirical relationship between the measured fields in both the NF and FF regions. Initial results show that the predicted FF emissions from a high-speed board provide the designer a good confidence on the compliance of regulatory emission limits.

Development of near-field emission limit from radiated-emission limit based on statistical approach

This paper discusses a novel approach to transforming a radiated-emission limit (e.g., CISPR 22 and FCC) from the far-field to the near-field region. The proposed approach combines data from a near-field scanner and a gigahertz transverse electromagnetic cell with statistics to establish a simple relationship between a near-field magnetic field and a far-field electric field. It is shown that the proposed approach has the potential to be a simple, quick, and fairly inexpensive tool for electromagnetic compatibility pre-compliance purposes.

Study of signal integrity and radiated emission of single ended and differential high speed digital signals crossing a slot

With increasing board complexity and operating frequencies, signal integrity (SI) and radiated emission (RE) compliance for high speed digital board is becoming a challenge to printed circuit board (PCB) designers. Together with higher routing density and multiple on-board power supplies, routing traces across split planes are unavoidable. In this paper, SI performance and RE of single ended (SE) and differential signals propagating across slots are studied. Using both experimental and numerical simulation approaches, the impacts of single ended and differential high speed digital signals across a split plane are investigated and analysed.

DC Power Supply Design for Broadband PLC Modem with Low Common-Mode EMI Coupling

A power line communications (PLC) test bed is designed to understand the mechanism of common-mode (CM) coupling from the PLC modem circuitry to the power lines. It is found that the step-down power transformer that provides the DC power supply to the modem circuitry causes significant CM current on the power lines. By removing the power transformer and powering the modem circuitry with an isolated DC source, we have demonstrated that the CM current on the power lines could be reduced by as much as 15 dB.