Tadahiko Maeda

A compact UWB antenna with dual band-notched characteristics using viahole structure

In this paper, a viahole structure is applied to realize dual band-notched characteristic in a compact planar monopole antenna for ultrawide band (UWB) applications. The proposed antenna consists of a modified radiating patch element and a ground plane. Three patches are etched on the back of the antenna and connected to the main patch by series of via holes to realize the WiMAX 3.5 GHz notched band and the WLAN 5.5 GHz notched band. The simulation and measurement show that the proposed antenna achieves an impedance bandwidth of 3.1–10.6 GHz with VSWR<2, except the bandwidths of WiMAX and WLAN. A nearly omnidirectional radiation pattern and stable gain are also obtained except in the notched bands.

A Basic Study on a New Composition of a Half-Scale Phantom for Evaluation of Ultra-Wide Band Wireless Systems

This report proposes a new composition for a half-scale phantom simulating the electrical parameters of the human body in the UWB frequency band. Electrical parameters were adjusted using polyethylene powder and calcium titanate to simulate the electrical characteristics of the human body in the UWB frequency band. It was confirmed that the fabricated phantom shows a maximum difference between experimental and target values of 12% for conductivity and 10% for relative permittivity. Topics for future research include the preparation of a phantom providing a difference within 10% of target values for both relative permittivity and conductivity, and actual measurement of antenna characteristics using the proposed phantom.

The Effects of Human Hands and LCD Panel on the Radiation Characteristics of Offset-Fed Slot Antenna of Notebook Computers for the Reception of Digital Terrestrial TV Broadcasting

Impedance and radiation characteristics of offset-fed slot antenna have been investigated for the reception of digital terrestrial TV broadcasting at 600 MHz including the effects of human hands and LCD (liquid crystal display) panel. First, the impedance characteristics of center-fed slot antenna have been obtained using finite difference time domain (FDTD) method. Then the impedance characteristics of offset-fed slot antenna have been simulated until the optimum feed point is achieved. According to the optimum results of the simulations, actual offset-fed slot antenna has been constructed on 300 mm times 210 mm copper plate. Then the impedance and radiation characteristics of the antenna have been simulated including the effect of human hands using FDTD method. It has been assumed that a metallic plate has the similar effect on the impedance and radiation characteristics of the antenna as that of the LCD panel of notebook computers. Therefore, the impedance and radiation characteristics of the antenna have been obtained including the effect of a metallic plate using FDTD method. Finally, experimental results have been obtained for the input impedance including the effects of the metallic plate and LCD panel, and compared for justification.

Learning effects of automatic composition design software for human-equivalent phantoms from 1 GHz to 5 GHz with linear and exponential regression analysis

This paper describes the learning effects of automatic composition design software for human equivalent phantoms. Five materials: water, silicone emulsion, glycerin, sodium chloride, and agar were selected to compose human equivalent phantoms. Based on the adaptive linear and exponential multiple regression analysis, the developed software generates two sets of compositions for each target phantom. This paper also presents the measurement results for the eyeball, brain, and stomach phantoms designed with the developed software as examples in assessing the design accuracies and learning effects of the developed software.

Stability of Step-tapered Design Alteration in Radius of Elements on Radiation Characteristics of Yagi-Uda Antennas

The radiation pattern of an optimized Yagi-Uda antenna does not suffer from the minor radius alteration (such as 1/2: 50% reduction or 1/4: 75 % reduction) of elements even if the alteration is uniform for entire elements. The minor step-tapered design alteration in radius of radiating elements greatly affects the radiation characteristics of the Yagi-Uda antenna, which is originally designed with the uniform radius. However, the step-tapered radius element structure of Yagi-Uda antenna shows the stable radiation characteristics in terms of the radius alteration.

The Effects of Feeding Cable Arrangements on Radiation Pattern Measurements Using Scale Model Phantoms

A method to measure the radiation characteristics of portable antennas during their development stages using a human-equivalent phantom to suppress the undesired current leakage along the RF feeding cable has been proposed and investigated. The basic assessment of the 351 proposed method was conducted through radiation pattern measurements using a scale model phantom as well as FDTD simulations. The results confirm that embedding the RF cable into the phantom reduces the effect of the RF cable on the measurement of the radiation characteristics. This method alleviates problems resulting from RF cable routing, and is considered an effective and practical method that may be applied to phantom-related measurements of an antenna system with both full phantoms and scale models. Finally, this method is simple and convenient to apply in practice because the shape of the solid phantom is easy to work with on site.

A study on the accuracy of location measurement of wireless ID tags integrated with multiple antennas and an antenna direction sensor

Location information of mobile terminals has become more important in relation to the achievements of the ubiquitous network, and studies of location measurement using wireless ID tag systems are attracting attention. Wireless ID tag systems are used for location measurement, and these systems usually have one antenna inside a wireless ID tag. However, the accuracy of these systems could be affected by the direction of the tags. Therefore, this study proposes a wireless ID tag integrated with multiple antennas and an antenna direction sensor in order to improve the accuracy of the system and examines the accuracy of the proposed wireless ID tag by basic experiments.

Three dimensional structural parameter analysis on a balanced-fed dual-band built-in antenna for wideband wireless LAN systems

This paper describes the basic design, the optimization, and the overall performance of the balanced-fed dual-band built-in antenna. The four major key structural parameters of this antenna including the additional parameter h3 were optimized for the dual-band operation in Japan using the efficient parallel Method of Moment based on the 16 parallel PC cluster system. The bandwidth of 340 MHz for 2.4 GHz band and that of 480 MHz for 5 GHz band have been obtained after the structural parameter optimization. Also, the RF current on the metallic plate was evaluated in order to confirm the validity of the proposed antenna with balanced-fed. Finally, the optimized antenna configuration was evaluated experimentally. The measurement results demonstrate the bandwidths of 246 MHz for 2.4 GHz band and 325 MHz for 5 GHz band, which are sufficiently wide for the assigned frequency bands for the 2.4 GHz WLAN system and the 5 GHz indoor W LAN system in Japan.