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Author: search.filters.author.Sooksumrarn, Pobsook

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    Wireless communications in a tree canopy
    (2013-09-03)
    Sooksumrarn, Pobsook
    ;
    Kittiyanpunya, Chainarong
    ;
    Yoiyod, Paiboon
    ;
    Krairiksh, Monai
    The wireless communications in a tree canopy is essential for pre-harvesting control of fruit productions. To effciently communicate between a sensor node and a sink node, channel characteristics in a tree canopy must be well-established. In this paper, propagation channel characteristics at the frequencies of 2.45 and 5.2 GHz have been estimated for designing a wireless communication system in a tree canopy. The proposed solution is based on measured path loss, time-varying signal strength and Angle of Arrival (AoA) for various paths in a tree canopy to estimate the channel. Since the waves re°ect, refract, di®ract and scatter from the foliage, it is complicated to find the true travelling path between a transmitter and a receiver at the nodes. The AoA estimator is used for physical interpretation of the channel. The experimental results demonstrate the channels in a tree canopy are mostly matched with the General Extreme Value model. The measured path gains illustrate that the appropriate antenna patterns must be selected to enhance the reliability of the system.
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    UHF wireless communication channel in a tree canopy
    (2012-12-01)
    Sooksumrarn, Pobsook
    ;
    Krairiksh, Monai
    A wireless sensor network has played an important role in various applications [1] including agriculture where it is essential in quality control of fruit production. Microwave sensors have been installed on fruits to monitor their ripeness and signals corresponding to the level of ripeness were sent from the fruits on a tree to the tree node on that tree and then to the master node to warn growers to harvest at the appropriate time [2]. For an effective design of a wireless communication system in a tree canopy, channel characteristics are highly desirable. The works on propagation through foliages have been comprehensively reviewed [3] but none of them were for propagation channel in a tree canopy. Hence, a propagation channel in a tree canopy is presented experimentally in this paper. © 2012 IEICE.
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    A dual-band dual-feed switched-beam patch antenna for WLAN application
    (2008-01-01)
    Tagapanij, Jukkrit
    ;
    Sooksumrarn, Pobsook
    ;
    Tantisopharak, Tanawut
    ;
    Janin, Suwan
    ;
    Krairiksh, Monai
    Due to the demand of dual-band modern wireless communications, this paper presents a dual-band patch antenna for IEEE802.11 a and g wireless local area network (WLAN) system. The antenna has bidirectional patterns that can be switched by an RF switch to select the feeding probe positions. The 2.4 GHz and 5.2 GHz patches are stacked on a ground plane and are matched to the RF switch by open stubs. Analysis and design are illustrated and throughput improvement is demonstrated in an indoor environment. Copyright © 2008 The Institute of Electronics, Information and Communication Engineers.