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In recent years, ultra-high-frequency (UHF) radio frequency identification (RFID) systems have drawn more and more attentions in a wide variety of applications such as retail item management, access control system, electronic toll collection, and etc. By incorporating with a commercial RFID reader, it has been noted that the phased array antenna can be implemented in a RFID system to either control...
In this paper, we proposed a novel design to further enhance impedance bandwidth by varying the shape of the open slot. The measured bandwidth of the proposed antenna defined by return loss >10 dB is about 130%, from 2.3 to 10.9 GHz. The proposed open slot antenna will be implemented, and the detail antenna design and experimental results are presented and discussed.
Metamaterials are artificially constructed to have special electromagnetic properties not found in nature. In recent years, metamaterial is noted as a new kind of device, and the composite right/left-handed transmission lines have been proposed, which are characterized by antiparallel phase and group velocities and negative refractive index. The materials were termed as left-handed materials due to...
In the paper, we have shown that in order to reduce influence of reflection waves, it is useful to average the radiation patterns which are measured by changing the distance between two antennas. The results using photonic balun are almost the same as those of the conventional balun. Because the presence of the coaxial cable does not affect the horizontal pattern measurements. We will apply the proposed...
Due to the low profile and the simple structure, the planar monopole antennas and the planar inverted-F antennas (PIFA) have been very attractive in the mobile handset applications. Although the planar loop antennas possess similar features, they have not been discussed extensively. Moreover, the urging requirement for multi-band operations makes the handset antenna design more and more challenging...
In this paper, the proposed small antenna, which using negative permittivity meta-material structure is designed, achieves wide Q more than calculated QL of chu limits. The equivalent circuit of proposed antenna is realized by Ansoft designer. The proposed small antenna is optimized by 3-D field simulation tool, CST MWS(micro wave studio).
In this work, approaches that aim to reduce SAR on human body were attempted. Algorithms were devised for automated antenna blockage assessment. These algorithms are used to determine the presence and location of obstacles in adjacent to a mobile device, A multi-antenna mock-up was fabricated to house several antennas at various locations on a palm-size device. According to the variation in the amount...
We have developed a new type of balun, called "photonic balun", to receive the balanced component of a RX antenna. Because the photonic balun is connected to a receiver through an optical fiber, we can realize an ideal antenna measurement free of unwanted effects of a coaxial cable. To demonstrate the superiority of the photonic balun in antenna measurements, we compare the vertical polarization...
In this paper, the miniaturization of a printed circular disc monopole antenna is investigated. It is shown that by halving the original antenna and adjusting the coplanar ground plane width, an even wider impedance bandwidth at the lower end can be obtained. Furthermore, a clear physical explanation is provided to illustrate the mechanism of this type of half circular disc antenna.
In this paper, we present a novel microstrip patch antenna specifically designed using planar metamaterial patterned substrate. It is developed based on an ordinary patch antenna, and isolated triangle gaps and crossed strip-line gaps are etched on the metal patch and ground plane respectively. This patterned substrate was demonstrated in literature to have left-handed characteristics. In this way,...
In this paper, the design concept of a rectangular normal mode helical antenna is explained. And calculated and measured antenna input impedance and gain are shown in the metal proximity condition. High antenna gain of 2.06dBd is ensured. Next, the antenna structure capable of matching to an IC chip is shown. By employing this antenna, the metal proximity use tag is fabricated. Communication distance...
In this paper, we presented several applications of millimetrewave EBG structures with controlled defects, fabricated using a rapid prototyping technique based on extrusion freeforming. Numerical simulations were performed for the design of millimetrewave woodpile structures. The fabricated woodpile structures have been measured and showed a good agreement with the simulated results. A directive millimetrewave...
In this paper, a small antenna for the applications of GPS and DCS systems by utilizing the CPW feeding structure is proposed to provide the LP and CP radiation patterns. The CPW feeding structure possesses the advantages, such as low radiation loss, less dissipation, uniplanar structure without the ground plane, and easy integration with RF/microwave circuits, enabling a miniature hybrid or monolithic...
Design, simulation fabrication and measurement of fractal antennas for wireless communications are presented in this paper Two types of geometries, i.e. Sierpinski gasket and Koch curve, were investigated. The proposed antennas are compact, can operate for multiple frequency bands and exhibit small mutual coupling.
Most of the biomedical images are studied with EM (electromagnetic) wave propagating to the tissues which is buried inside the higher dielectric material. In this paper, the dipole antenna is designed for studying the biomedical imaging of tissues which is buried inside the water. Due to the material of the dipole antenna was made from coaxial cable; therefore it has waterproof capability. The scattering...
In this paper, a dual spiral antenna for ultra-wideband capsule endoscope system is proposed. Since a capsule endoscope system which transmits real-time image data in the body should have ultra-wideband characteristic, an ultra-wideband antenna is suitable for this system. When an antenna is used as capsule endoscope system, a small sized antenna is required because capsule is small enough to be swallowed...
This paper presents a broadband omnidirectional vertically polarized antenna of only a one eighth wavelength associated to the lowest frequency. This antenna is composed of a conical monopole with metallic parasitic elements, a capacitive disk and a dielectric substrate placed above a square ground plane. This structure provides broadband performances and omnidirectional radiation patterns over the...
In this paper, a dual-band circularly polarized antenna is designed for the UHF band (860 MHz ~ 960 MHz) and ISM band (2.4 GHz ~ 2.48 GHz) RFID reader applications and novel microstrip patch RFID tag antennas for the UHF RFID band (908 MHz -914 MHz) in Korea are proposed. They have less sensitive characteristic against the size of metallic object, wide impedance bandwidth and a long reading distance.
Specific absorption rate (SAR) assessment plays a crucial role in the development of small antennas for wireless systems. Indeed, such antennas are generally in close interaction with human body, resulting in exposure safety issues. While the standard procedure remains the reference to ensure compliance with existing norms, various needs for faster SAR measurement have been pushing for the development...
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