Jun Wu Zhang

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.

Printed Decoupled Dual-Antenna Array On-Package for Small Wirelessly Powered Battery-Less Device

A printed compact antenna array for small wirelessly powered device operating at 900 MHz is proposed. The prototype is developed by printing antenna pattern on a 0.1-mm-thick flexible substrate and folding the printed sheet into a rectangular volume measuring 35 × 56 × 12 mm 3. The edge-to-edge distance between array elements is only 0.078 λ. An isolation structure is added to minimize the coupling between the elements. Measurement results show a -27-dB minimum coupling between the elements, which yields significant gain improvement up to 3.6 dB and radiation efficiency improvement up to 28% over the design without isolation structure. When integrated with rectifier circuits, the proposed design also demonstrates superior performance by generating more dc power. The results have shown the proposed work to be a feasible solution of implementing antenna array for small device to enhance of RF power receiving capability with high compactness.

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.

Evaluation of fibre weaving of substrate on differential striplines using an analytical approach

Electrically long differential signal traces may introduce significant signal skew due to weave effect that deteriorates the signal quality. As serial data link pushes towards higher data transfer rate and yet the length of the signal trace has not reduced, the weave effect will become significant. Full wave method is often used to study the weave effect, however, the computational time is expensive. As such, a novel analytical method is proposed in this paper to study the fibre weave effect in PCB dielectric.

Pre-layout multi-layer PDN model for high-speed board

A method on developing pre-layout PDN model utilizing 3D full-wave simulation was proposed in this work. The proposed method divides the PDN into different blocks and obtains the network parameters of each block using 3D full-wave simulation. The proposed method was validated with post-layout simulation. Results show that PDN impedance obtained from pre-layout PDN model developed using proposed method agrees well with post-layout simulation result.

Flexible printed two-element antenna array with enhanced isolation performance

A 3D compact antenna array printed on package was proposed for RF powered battery-less device operating at 900MHz. The array-integrated package has size of 33 mm by 56 mm by 12 mm, whose largest dimension is only 0.2λ at 900 MHz. Each radiating element is connected to a circuitry on PCB through inductive coupling and hence no direct electrical contact between PCB and the package is needed, which greatly simplifies the assembly process. An isolation structure is added to minimize the coupling between closely spaced array elements. The prototype was fabricated by printing the antenna array on 0.1 mm thick PET sheet and by folding the sheet into a rectangular package. A maximum isolation of 30 dB between the two array elements was demonstrated for the proposed design. The measured radiation pattern also reveals the importance of the isolation component. It shows maximum gain of 1.1 dBi and 0.7 dBi is achieved for each array element of the proposed design, which is significantly higher than that of the reference design without any isolation.

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.

Estimating frequency spectrum of IC power supply current through time-domain voltage measurement on power distribution network

A method to estimate the frequency spectrum of IC power supply by measuring transient voltage on Power Distribution Network (PDN) was proposed in this work. The proposed method was validated through measurement on a testing board with three clock driver ICs. The result show good agreement between the estimated current spectrum and measured current spectrum at the major spikes.

Influence of RF noise on automotive TFT power distribution network on radiated emissions

With increasing consumers demand and technological advancement for automotive electronic systems, it is becoming a challenge to ensure good compliance for high speed design (signal and power integrity) and electromagnetic compatibility. In this paper, the effects of high frequency switching noise from an automotive cluster coupling into a TFT display module, causing undesirable radiated emissions is presented. Experimental results, demonstrating the importance of good power supply filtering to prevent RF noise from coupling into the TFT display from an automotive instrumentation cluster is demonstrated. In addition, complex modeling of the entire power distribution network, consisting of PCB and FPC is performed. With the model, the PDN impedance with and without EMC considerations can be simulated and analyzed.