Noriaki Odachi

High-speed DOA estimation using beamspace MUSIC

MUSIC (multiple signal classification) has been widely used to estimate the direction of arrivals (DOAs) accurately. However, this method requires a large calculation time for eigen-decomposition of the covariance matrix. This paper presents a high-speed DOA estimation based on the beamspace MUSIC, which can reduce the order of the covariance matrix. The proposed method implements a two-step DOA estimation. The first step is the coarse estimation in which the DOAs are roughly estimated. The second step is the fine estimation in which the result of the coarse estimation is exploited and the DOAs are accurately estimated.

A study on the variable radiation pattern antenna using a parasitic slot

It is advantageous for cellular phones or WLAN-APs (wireless LAN access points) that their antennas have variable radiation patterns in certain cases, such when they are mounted on a wall or for the purpose of avoiding interference. Most conventional antennas, such as reactively controlled directive arrays, are composed of multiple elements of identical shape to resolve the above-mentioned issues. This work proposes a novel variable radiation pattern antenna consisting of an inverted-F antenna and a parasitic slot with an electrical switch, and shows its fundamental characteristics and the appropriateness of its parameter optimization with GA.

A rod antenna with a meander element for hand-held phone

This paper proposes a rod antenna with a meander element mounted on a hand-held phone. The quarter-wavelength meander element can improve the input impedance of a half-wavelength rod antenna. The reason for the improvement of the input impedance is that the total length of the antenna is three quarter-wavelengths. Also, the proposed antenna can realize a high gain in the horizontal plane. The reason for the high gain in this direction is that the meander element is optimized to radiate in the horizontal direction so as to add to the radiation from the antenna.