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22 The PCB Magazine • October 2014 a smartphone. Since the athlete is wearing the sensor, size and weight are of primary concern. Most systems consist of helmets or skullcaps, while one supplier has succeeded in miniaturis- ing the electronics to the point where every- thing is contained in a headband (Figure 3) and transmitted to the sidelines. While first-generation systems are attract- ing a lot of attention it is clear that longer range and/or alternatives to BLE such as WiFi will enhance functionality and effectiveness, giving the coach or trainer realtime feedback on traumatic stress events. Diversification and short product introduction cycles will tend to exclude highly integrated solutions such as sys- tem-on-chip (SoC) unless a custom processor platform can support an upgradeable software defined user experience as in the case of Apple's recently introduced Apple Watch (Figure 4). In addition, an integrated packaging (chip scale, wafer level)-on-PCB approach not only tends to introduce parasitics at RF frequencies but is also limited to the specifications and performance of the individual components which make up the circuit. New developments incorporating a novel approach to managing the electromagnetic properties of materials are set to change this paradigm. Engineered Materials + System-in-Package = "Better than Book" One of the bottlenecks in the design of small, interconnected devices is the antenna. Wireless connectivity is the de facto standard for data storage and transfer, with 900MHz, 1.5GHz, and 2.4GHz the most popular spectra due to the massive proliferation of ISM (indus- trial/scientific/medical) band devices, GPS, BLE, and the various flavors of Wi-Fi. However, wear- able is a distinct category that requires new at- tention in integration technologies. Applying portable or mobile electronics techniques to an- tenna and RF design has been shown to provide suboptimal performance, primarily due to the much smaller geometries necessary for wearable transceivers. For example, users of wearable GPS devices have probably noticed that the time to first fix (TTFF) is always long. For wearable wireless con- WEARABLE ELECTRONICS continues figure 3: sports impact detection system. (source: triax technologies) figure 4: apple's computer on a chip. (source: apple)