Miniaturized Reflectarray Unit Cell Using Fractal-Shaped Patch-Slot Configuration

A large literature establishes the benefits of discussions for stimulating student engagement and critical thinking skills. However, we know considerably less about the differential effects of various discussion environments on student learning. In this study, we assess student perceptions concerning the benefits of discussions in an upper-level political science class. We compare how students evaluated discussions in the whole-class environment, in small face-to-face discussion groups, and in online discussion groups. Overall, according to student surveys, small discussion groups elicited the highest student satisfaction and scored highest in critical thinking skills, while online discussions provided the best forum to express thoughts. While they did not favor all-class discussions, students reported that this format, too, provided benefits

Miniaturized On-Chip NFC Antenna versus Screen-Printed Antenna for the Flexible Disposable Sensor Strips

With the ongoing trend toward miniaturization via system-on-chip (SoC), both radio-frequency (RF) SoCs and on-chip multi-sensory systems are gaining significance. This paper compares the inductance of a miniaturized on-chip near field communication (NFC) antenna versus the conventional screen-printed on-substrate ones that have been used for the transfer of sensory data from a chip to a cell phone reader. Furthermore, the transferred power efficiency in a coupled NFC system is calculated for various chip coil geometries and the results are compared. The proposed NFC antenna was fabricated via a lithography process for an application-specific integrated circuit (ASIC) chip. The chip had a small area of 2.4 × 2.4 mm2, therefore a miniaturized NFC antenna was designed, whereas the screen-printed on-substrate antennas had an area of 35 × 51 mm2. This paper investigates the effects of different parameters such as conductor thickness and materials, double layering, and employing ferrite layers with different thicknesses on the performance of the on-chip antennas using full-wave simulations. The presence of a ferrite layer to increase the inductance of the antenna and mitigate the interactions with backplates has proven useful. The best performance was obtained via double-layering of the coils, which was similar to on-substrate antennas, while a size reduction of 99.68% was gained. Consequently, the coupling factors and maximum achievable power transmission efficiency of the on-chip antenna and on-substrate antenna were studied and compared