This paper proposes on an effective mutual coupling suppression technique for planar phased array. This is achieved locating a metamaterial superstrate patch between radiation elements of phased array. The superstrate patch is realised by incorporating slots inside the patch, where the slots are arranged in 2×3 array column. The proposed mutual radiation decoupling technique is implemented on FR-4 substrate. Average coupling suppression of 5 dB is achieved on a low permittivity substrate over its operational frequency band. The proposed technique is (i) simple to implement; (ii) planar design; (iii) easily realised in practice; (iv) overcomes the shortcomings of poor front-to-back ratio previously reported in other radiation suppression techniques; and (v) applicable for densely packed microstrip. Furthermore, the proposed planar technique is highly versatile for various applications having stringent performance requirements.
The mechanism of propulsion in swimming has been widely researched in recent years, but not completely clarified. While it is obvious that the movement of arms provides most of the thrust, it is unclear how each phase of the stroke translates into body acceleration. Investigation is carried out mainly by video analysis or using Inertial Measurement Units (IMUs) which do not measure forces. In this paper, we present a wearable data acquisition system for swimmers. The system is composed of two instrumented paddles, measuring the pressure difference between palm and back of the hands, and an IMU. The paddles provide information about the forces that cause propulsion, while the IMU measures the effects of these forces. Data are acquired by a microcontroller unit placed in waterproof case at the athlete's waist, and transferred to PC via a Bluetooth link. Early experimental data are presented.
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