Kenichi Kagoshima

New indoor high-speed radio communication system

We propose a new concept for indoor high-speed radio communication includes a no-wiring relay station (RS) on the ceiling. The concept offers very simple set up procedures, and flexibility in composing and adjusting radio zones. We introduce a prototype of the RS, which operates using the voltage supplied to standard fluorescent sockets. Planar multibeam and pencil-beam array antennas for the RS are designed by using an improved indoor propagation delay simulation algorithm.

Mean Effective Gain of Mobile Antennas in Line-of-Sight Street Microcells With Low Base Station Antennas

A method for evaluating the mean effective gain (MEG) of mobile antennas in line-of-sight (LOS) street microcells with low base station antennas is investigated. The received power patterns of incident radio waves along typical streets measured in actual street microcells in urban areas of Tokyo are presented to clarify the proper distribution model for the incident radio waves. A two-dimensional statistical distribution model is proposed based on the measured received power patterns for the incident radio waves that follow a Gaussian distribution in the azimuth angle, but are concentrated in the horizontal plane in the elevation angle. The two-dimensional theoretical expression of the MEG that consists of the incident distribution model function and the radiation patterns in the horizontal plane of the mobile antennas is derived to evaluate easily the MEG. We show that the MEG values in street microcells are not defined as only one value and form the MEG pattern because the MEG values are changed by the relative direction of the radio waves arriving at the mobile station antennas. The measured and calculated MEG values (MEG patterns) of the whip antennas used in the experiments are in good agreement. The average error between the measured and calculated MEG values is within approximately 4.5 dB at maximum. The results show that the MEG degradation of the mobile station antennas due to the effect of the human body is properly evaluated by the proposed distribution model. The proposed statistical distribution model is valid and effective in both estimating the MEG values of mobile antennas and designing the LOS street microcell systems with low base station antennas.

Effectiveness of four-branch height and polarization diversity configuration for street microcell

This paper proposes a four-branch height and polarization diversity configuration that achieves almost constant received signal power over any terminal inclination in a street microcell communication environment. An example of the four-branch diversity antenna is also presented. Our measurement results in cell-size comparison among height diversity, polarization diversity, and height and polarization diversity configurations confirm the effectiveness of the proposed diversity configuration.

Pattern control antennas for wireless access systems

Pattern control antennas are defined as the antennas designed their radiation patterns to enhance the radio channel performance of the systems. In wider meanings, static antenna pattern controls like shaped beams and low sidelobes are included in this category. However, dynamic pattern controls are more effective to improve the radio channel performance, especially in broadband and mobile wireless systems. In this, first the necessity of pattern control antennas is described for the wireless access systems. Second, the candidates of pattern control antennas to satisfy the requirements of the system are presented. Next, practical examples, which are multi-sector beam switching antennas, are introduced and the principal characteristics of the antennas are described.

A three-dimensional active antenna for a high-speed wireless communication application

This paper proposes a three-dimensional active antenna configuration for a front-end module of a high-speed wireless communication system at millimeter and quasi-millimeter-wave frequencies. The active antenna is integrated with a microstrip antenna array on multilayer alumina-ceramic, individual MMIC chips including transmit/receive amplifiers, time division duplex switches, and a filter on multilayer polyimide. The three-dimensional structure achieves an unrestricted RF-circuit design on multilayer polyimide.

Feasibility of RSSI based access network detection for multi-band WLAN using 2.4/5GHz and 60GHz

This paper describes feasibility of RSSI (Received Signal Strength Indicator) based access network detection for multi-band WLAN (Wireless LAN) using 2.4/5GHz and 60GHz aiming at power-saving of multi-band WLAN device and higher spectrum efficiency. The proposed scheme detects 60GHz coverage by using 2.4/5GHz WLAN signals without using 60GHz WLAN signals for on/off control of 60GHz part of multi-band WLAN device. This makes it possible to turn off 60GHz part whenever a multi-band WLAN device is out of 60GHz coverage. Ray-tracing simulation results indicate that the proposed RSSI based access network detection is feasible.

A planar sector antenna for indoor high-speed wireless communication terminals

Wide-band digital indoor communication systems, such as wireless LANs and wireless ATMs, are being developed in the quasi-millimeter and millimeter wave frequency bands. In such high-speed systems, the degradation of transmission quality by multipath fading is a significant problem. Since wireless communication users operate their terminals without knowing the direction of the other station, the antennas should cover all directions with narrow beams. In addition, the antenna gains should be equalized in all directions. A sector antenna consists of narrow beams radially oriented and the beams are electrically switched to select the best signal. Therefore, its hardware is not complex and control is fairly simple. This paper shows a new methodology for realizing planar sector antennas. The sector antenna uses two kinds of beams formed by two kinds of antennas: planar 4-beam subarrays and planar single-beam subarrays. In order to equalize the antenna gains in all sectors, the beam shapes are carefully designed to offset the movement experienced by portable terminals. The 4-beam subarray is a multi-beam antenna integrated with a planar Butler matrix feeding circuit. The design method of the subarray and an evaluation of its characteristics in the 19 GHz band are discussed.

Design and analysis of transmitting and receiving characteristics of a small MIMO array antenna with a matched load

A new design formulas for a N×N matching network for an array antenna with mutual coupling is presented. Using matching conditions, decoupling between excitation ports and beam orthogonality have been explicitly verified. Numerical results of the antenna pattern in the vertical plane suggest that the received power of a two elements array is two times larger than a single dipole. A method for enhancing frequency characteristics and a new definition of a receiving antenna efficiency are also proposed.

Novel Microstrip Antenna With Rotatable Patch Fed by Coaxial Line for Personal Handy-Phone System Units

An enhanced microstrip antenna is proposed that incorporates a patch that rotates around the inner conductor of the coaxial line or dielectric shaft and a novel coaxial line feeding technique that offers constant electromagnetic coupling. This proposal addresses the disadvantages in our previous patch antenna in which the resonant frequency diverges from the center frequency of the personal handy-phone system (PHS) band and the bandwidth decreases as the patch rotates because of the changing electromagnetic coupling between the patch and microstrip line due to the patch rotation. We verify that this enhanced patch antenna achieves the antenna gain of approximately 0 dBd, which is the same as that of the previously proposed antenna, while suffering no significant gain degradation due to unit inclination over inclination angles from plusmn45deg compared to a conventional quarter-wavelength whip antenna, which experiences a degradation of approximately 2.7 dB. We show that the maximum resonant frequency separation from the center frequency of the PHS band is reduced to 15 MHz from 31.4 MHz of the previous antenna using the novel coaxial line feeding technique. The effective bandwidth needed for PHS is achieved over the inclination angles of -20deg to +40deg. Approximately 93% of the total bandwidth needed for PHS is achieved while the previous microstrip line type achieved only 58% coverage; accordingly, an adequate bandwidth for PHS use is obtained.

Proposal for a novel beam combination method for indoor high-speed wireless communication systems

A novel beam combination method for wide-band digital indoor communication systems such as wireless LANs and wireless ATMs is proposed. Crossed fan beams are used at the base station (BS) and personal stations (PSs). The beam combination method provides better transmission quality than the traditional pencil-beam combination and eliminates complex beam control in the BS. Maximum dispersion distributions in a transmission frequency bandwidth are calculated by a three-dimensional (3-D) indoor propagation delay simulation algorithm. A prototype fan-beam antenna for the PS is fabricated and measured at 20 GHz.