Abstract: An adaptive array antenna is disclosed which permits the circuit scale to be reduced by omitting a down-converter, an AD converter, and interconnects for them while controlling the directivity well. In one aspect, the array antenna comprises phase shift-amplitude control modules which accept signals received by antenna elements via an analog-to-digital converter. The value of any one of phase-amplitude change modules is set to 1. The values of the other phase-amplitude change modules are set to 0. Thus, the signal from any one antenna element is accepted. This sequence of operations is repeated as many times as there are antenna elements, whereby signals received by all the antenna elements can be accepted.

Abstract: An adaptive array antenna is disclosed which permits the circuit scale to be reduced by omitting a down-converter, an AD converter, and interconnects for them while controlling the directivity well. In one aspect, the array antenna comprises phase shift-amplitude control modules which accept signals received by antenna elements via an analog-to-digital converter. The value of any one of phase-amplitude change modules is set to 1. The values of the other phase-amplitude change modules are set to 0. Thus, the signal from any one antenna element is accepted. This sequence of operations is repeated as many times as there are antenna elements, whereby signals received by all the antenna elements can be accepted.

Abstract: A calibration apparatus for a quadrature modulation system with a quadrature modulation compensator and a logarithmic envelop detector, wherein a parameter update of the quadrature modulation compensator is derived by utilizing a transformed offset value and a transformed gain value of the logarithmic envelop detector as intermediate parameters, and the transformed offset and the transformed gain parameters are used in a training sequence of the quadrature modulation compensator.

Abstract: A calibration apparatus for a quadrature modulation system with a quadrature modulation compensator and a logarithmic envelop detector, wherein a parameter update of the quadrature modulation compensator is derived by utilizing a transformed offset value and a transformed gain value of the logarithmic envelop detector as intermediate parameters, and the transformed offset and the transformed gain parameters are used in a training sequence of the quadrature modulation compensator.

Abstract: A bidirectional optical communication apparatus is composed of a set of a first device (1) and a second device (2). Using linear-polarization plates (11A, 11B, 21A, and 21B) and quarter wavelength plates (31A, 31B, 41A, and 41B), a transmission section (TX1) of the first device (1) radiates a first signal (Ls1) consisting of circular polarization in one of the rotational directions, while a reception section (RX2) of the second device (2) receives only these circular polarization components. In addition, a transmission section (TX2) of the second device (2) radiates a second signal (Ls2) consisting of circular polarization in the other rotational direction, while a reception section (RX1) of the first device (1) receives only these circular polarization components. This configuration enables bidirectional optical communication without complicated communication control and accurate optical-axis alignment.

Abstract: It is an object of the present invention to provide a method and an apparatus for driving a piezoelectric transformer capable of always driving with maximum conversion efficiency regardless of changes in the input voltage level, load and temperature, etc.