Abstract: A reception unit receives signals from a plurality of radio terminals. A transmission unit transmits signals to the radio terminals. A direction determination unit determines the directions of the radio terminals viewed from the transmission unit on the basis of the signals received by the reception unit. A group selection unit distributes, by using a threshold, the transmission powers or downlink data transmission rates of radio terminals which transmit signals in a time-overlapping manner, thereby classifying the radio terminals into two groups. Then, the group selection unit selects a group having a smaller total number of radio terminals. A directivity pattern control unit controls a directivity pattern on the basis of the directions of the radio terminals determined by the direction determination unit.

Abstract: To simplify designing and fabrication of a shaped beam array antenna for generating a cosecant square beam, slots having the same size are arranged with the same separation on a wall of a wave guide. The slots yield an excitation amplitude distribution wherein the excitation amplitude distribution attenuates exponentially from a feeder side of the wave guide to the terminal side of the wave guide where a terminal dummy is provided. The excitation phase distribution is linear with a slight variation. The first slot nearest to the feeder side is modified to produce an excitation phase difference between the first and the second slot.

Abstract: There is provided an antenna including (a) a first micro-strip antenna, (b) a second micro-strip antenna spaced away from and facing the first micro-strip antenna, (c) a ground plate located between the first and second micro-strip antennas, the ground plate being formed with an opening overlapping both the first and second micro-strip antennas, (d) a first dielectric material sandwiched between the first micro-strip antenna and the ground plate, (e) a second dielectric material sandwiched between the second micro-strip antenna and the ground plate, and (f) a micro-strip line formed on a surface of the first dielectric material and connected to the first micro-strip antenna. In accordance with the antenna, when electromagnetic wave is supplied to the first micro-strip antenna, the first micro-strip antenna resonates and radiates electromagnetic waves to atmosphere therearound.