Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Suthasinee LAMULTREE"

Gain Improvement of Dual-Band Circular Monopole Antenna for 2.45/5.5 GHz WLAN Applications DOI:10.15199/48.2019.05.37

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With Rapid developments of modern wireless communications, various microwave technologies have been utilized for different applications, which make the microwave spectrum more crowded. Wireless fidelity has transformed in to the standard for wireless local area network (WLAN) communications in the 2.45 and 5.5 GHz ISM bands, with the frequency ranges from 2.4 to 2.485 GHz as well as 5.150-5.350 GHz, 5.470-5.725 GHz, and 5.725-5.850 GHz [1]. For system flexibility and feasibility, antennas that are capable to serve in both of the specified operation bands are highly attracted. For this reason, dualantennas are promoted to overwhelm the 2.45- and 5.5 GHz WLAN bands [2]-[10]. A dual-band antenna can be usually accomplished by utilizing two types of singlefrequency antennas for each band [8], and taking a dualfrequency antenna for two separate bands [5], [9]. For the two types of single-frequency antennas, two external feeding networks must be come up with these individual dual-band antennas, which probably entail some structural sophisticates into applications [8]-[9]. As mentioned above, an element to make up a dualband antenna is more suitable to employ a dual-frequency antenna. There are many techniques to design for WLAN dual-band, such as using quarter-wavelength resonant slots in different shapes, coplanar fed, parasitic elements, and defected ground plane [5]-[13]. Latterly, many researchers adopt an attention on printed slot antennas (PSA), since wide-slot antennas have two orthogonal resonance modes, which are combined to form a wide impedance bandwidth [14]. As reported for increasing impedance bandwidth, antennas with various shapes like circle, ellipse, and triangle were introduced [15]. In our previous work [12], we presented the design and implementation of dual band with partial ground plane (PGP); nonetheless, its gain is not high. Hence, a technique to enhance the radiation performance of a microstrip-fed ci[...]

Design and Measurement of a Probe-Fed Open-Ended Rectangular Waveguide with Four-Stacked-Coupling-Aperture DOI:10.15199/48.2019.06.13

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Point-to-point communication systems have promptly advanced and become one of the growing communication business over the late decades [1]-[2]. Particularly, point-topoint links between hosts and clients are required in numerous wireless communication systems over long distances, for examples, the microwave radio relay link, long length Wi-Fi, wireless WAN/LAN link, satellite communication, and home satellite television, etc. [2]-[4]. To increase the performance of the point-to-point communication desires a narrow-beam or pencil beam antenna with high gain [5], which is probably provided by a reflector antenna. To generate pencil beam for point-topoint communications, a symmetrical beam antenna is required for a primary feed [6], since the radiation pattern of the secondary antenna (reflector antenna) typically corresponds to that of the primary feed antenna [7]. However, it is not easy to obtain symmetrical radiation pattern because of the asymmetrical beamwidth between the yz- and xz-planes depending on the antenna structure [8]. The development of symmetrical beam antennas has been continuously researched and proceeded [9]-[12]. Among these symmetrical beam antenna designs, a tripleaperture waveguide antenna (TAWA) was lately introduced to be a primary feed antenna for reflector [11], because its structure is not complex. Nevertheless, the radiating section of TAWA is not small size. To further reduce the size of that radiating section, a probe-fed open-ended rectangular waveguide (OERW) with four-stacked-coupling-aperture (FSCA) antenna was preliminary studied for designing a symmetrical beam antenna in 2018 [12]. It was found that the effect of FSCA could transform the asymmetrical beam to be symmetry at -3 dB beamwidth. However, an equal beamwidth of both yz- and xz-planes at -10 dB could not accomplish yet. Therefore, this paper aims to continuously improve the FSCA for the better symmetrical beamwidth at -10 dB b[...]

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