Solar energy is abundantly in nature and sustainable energy resources around the world. The main challenge with the solar field is less amount of sun energy captured by using photovoltaic (PV) systems. The great performance of the PV systems can be achieved if the panel is kept perpendicular to the direction of the radiations of sun. Hence, solar tracker system is the method to keep the optimum position of the PV panel for always perpendicular to the solar radiation. This paper aims to review on various technologies of solar tracking to determine the best PV panel orientation. The various types of technologies of solar tracking system have been discussed which includes passive solar tracker, active solar tracker and chronological tracker system. The movement degrees of solar tracking system also have been addressed which consisting single-axis solar tracking system and dual-axis solar tracking system. This paper is also overviews the tracking techniques performance, construction, performance, advantages, and disadvantages of existing solar tracking system. The limitations of solar tracking systems are also highlighted for future action improvement. Through this research studies, the most favorable solar tracking system was identified as active solar tracker with the dual axis rotation.
In this paper, a novel compact tree-design antenna (NCTA) for ultra-wideband (UWB) application with high gain and impedance matching improvement is analyzed and presented. The novel antenna is composed of a single centered circle connected to seven outer circles via three bridges with partial ground plane execution. Instead of functioning as filters, these seven circles play a major role in producing UWB's frequency resonant of 3.3 to 10.8 GHz with a minimum reflection coefficient of −10 dB (|S 11 | < −10 dB). Furthermore, this compact antenna structure (38 mm × 38 mm) which is fed by the microstrip line generates a high gain of up to 5.5 dBi. Moreover, the proposed tree-design antenna possesses a linear polarization with a proficient omni-directional radiation pattern at 3.5 and 5 GHz and a divisive radiation pattern at 7.5 and 10 GHz. The parametric study performed for the purpose of antenna compaction is emphasized in the details of this research. The numerical and measurement results exhibit the success of the antenna's performance. The attainable NCTA is sufficiently competent to be an initial structure consideration for the future Multi-Input Multi-Output (MIMO) development.
Abstract-A simple geometrical Asian-hand model with human tissue properties posed at two common talk-mode positions is proposed for comparative study. The newly designed hand is formed by measuring an adult female hand at open-hand position before being posed into the presented styles. Four human hand tissues are included: skin, bone, muscle, and tendon, and also three homogeneous sets of hands using specific anthropomorphic mannequin (SAM) hand phantom dielectric properties. A candy-bar type mobile phone with Planar Inverted-F Antenna (PIFA) is used to radiate dual-band frequency of GSM900/1800 in the vicinity of the SAM head phantom. The mobile phone casing is made out of plastic, and only two components are considered: the FR-4 ground plane and PIFA. The specific absorption rate (SAR) averaged over a mass of 10 gram and 1 gram is calculated after obtaining the power loss density and electric field value from simulation in CST Studio Suite 2011. The SAR and return loss results of six hand structures, including the SAM hand phantom are compared. The antenna performance with the inclusion of hand does not decrease as much as 1800 MHz in 900 MHz range, but absorbs energy more in the hands for 1800 MHz than 900 MHz SAR values.
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