Shigeki Obote

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In this paper, we propose a speedup method of frequency switching time in the phase locked loop (PLL) frequency synthesizer using the target frequency detector (TFD). The TFD detects the time Ta for any channels where the output of the PLL frequency synthesizer reaches the target frequency for the first time. At Ta, the programmable divider, the reference(More)
Decoupling and matching feeding networks are considerably interested in small wireless terminals to enhance their abilities for MIMO systems. In various proposals of DMFN's, the feeding networks composed of bridge susceptances and transmission lines are simple. However, this DMFN has only been applied to the limited array with special characteristics. This(More)
We discussed the radiation and reception properties of an array antenna with a decoupling and matching feeding network. When the feeding network is designed and constructed to satisfy the matching condition of the array antenna, each port pattern exhibits orthogonal property and eigen mode patterns when the orthonormal matrix, which constitue the sub matrix(More)
Decoupling and matching feeding networks are considerably interested for small wireless terminals to enhance their abilities in the application for MIMO systems. This paper describes various kinds of decoupling and matching feeding networks and derives the formulas for determining the network elements explicitly. Numerical results are presented to ensure(More)
This report aims to utilize existing and future Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing Wireless Local Area Network (MIMO-OFDM WLAN) systems characteristics-such as multiple subcarriers, multiple antennas and channel estimation characteristics-for indoor location estimation systems based on the Direction of Arrival (DOA)(More)
In order to solve a problem of maximizing a directivity of a transmitting array antenna with nulls at specified directions, we intended to utilize an adaptive antenna algorithm which enables the SNR to be maximum under the incidence of interferences. However, we encountered the discrepancy between transmitting antenna patterns and receiving ones. We(More)