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Introduction
Wearable RFID systems should be low-profile, lightweight, flexible, and breathable, in order not to hinder the user’s body movements. Planar textile antennas are a perfect choice for integration into clothing as they meet all the above requirements. Moreover, textile antennas are composed of environmentally friendly materials.
Exploiting the large platform garments have to offer, multiple antennas are readily implemented onto the human body. The high radiation efficiency of the proposed textile antennas, combined with a multi-antenna setup, provides a solution to the “energy problem” by creating very reliable communication links at a low transmitted power. Therefore, textile antennas are an excellent choice for green RFID applications.
Multi-antenna systems increase communication reliability using several techniques. A MIMO technique such as space–time block coding provides diversity gain, which mitigates the effects of fading by the environment. The use of dual-polarized textile antennas doubles the number of exploitable signal paths for an equal number of antenna patches on the body. Beam forming techniques can concentrate the transmitted power towards the receiver, which potentially results in a performance increase for an off-body RFID system at a reduced cost, compared to space–time coding techniques for transmit diversity used in MIMO systems.
New wireless wearable monitoring systems integrated in professional garments require a high degree of reliability and autonomy. Active textile antenna systems may serve as platforms for body-centric sensing, localisation, and wireless communication systems, in the meanwhile being comfortable and invisible to the wearer. We present a new dedicated comprehensive design paradigm and combine this with adapted signal-processing techniques that greatly enhance the robustness and the autonomy of these systems. On the one hand, the large amount of real estate available in professional rescue worker garments may be exploited to deploy multiple textile antennas. On the other hand, the size of each radiator may be designed large enough to ensure high radiation efficiency when deployed on the body. This antenna area is then reused by placing active electronics directly underneath and energy harvesters directly on top of the antenna patch. We illustrate this design paradigm by means of recent textile antenna prototypes integrated in professional garments, providing sensing, positioning, and communication capabilities. In particular, a novel wearable active Galileo E1-band antenna is presented and fully characterized, including noise figure, and linearity performance.
The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?
In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.
The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.
EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.
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