K. Inagaki

Spatial optical beam-forming network for receiving-mode multibeam array antenna - proposal and experiment

This paper proposes an array antenna for multibeam reception with a beam-forming network (BFN) that uses spatial optical signal processing and also presents experimental results. In this antenna, signals received at individual antenna elements are converted to optical signals, and are optically divided from the directions of signal arrival by means of optical spatial Fourier transformation, and then the optical signals are reconverted into microwave signals at the BFN. In this BFN, to maintain optical path-length conditions, an optical integrated circuit is employed. We have experimentally investigated the optical signal processing performances of the BFN for multibeam reception. The experimental results show that optical beam direction is changed according to the signal arrival direction of an array antenna. Two multiple RF signals with different phase distributions are separated. The sidelobe level of the optical signal is reduced when amplitude distributions of optical signals are Chebyshev distributions. We also present the signal transmission behavior of this BFN. The measured carrier-to-noise-ratio degradation of this BFN is 2 dB at BER=10/sup -6/ when 118.125-Mb/s QPSK modulated signal is input into the BFN.

Receive mode of optical signal processing multibeam array antennas

A receive mode of the optical processing array antennas is presented. In this receive mode, the transmitting radio frequency (RF) signals generated by optical processor will be shifted as local oscillator (LO) signals, and the received RF beams will be discriminated in the downconverted intermediate frequency (IF) frequency domain by a mixer array between the optical processor and antenna elements. A proof-of-concept experiment for a two-beam and four-element array antenna is demonstrated, and the received IF power distributions for each beam have very good agreement with the calculated antenna patterns.

Wide-band millimeter-wave/optical-network applications in Japan

This paper describes work on wideband millimeter-wave/optical network applications in Japan, especially projects being pursued at ATR. Results of fundamental transmission experiments demonstrate the feasibility of digital signal transmission at 118 Mbps with a BER of less than 10/sup -6/. In addition, an advanced system considered suitable for future high-speed mobile communications is proposed. This system employs an intelligent multibeam antenna and the direction of each sharp beam can be controlled adaptively. An optical signal processing array antenna is found to be suitable for this system, and several key technologies for system construction are described.

Spatial optical processing array antenna for multibeam reception

We propose a multibeam receiving antenna using spatial optical processing technique in a beam forming network. Also we experimentally investigate the basic performance of optical-microwave conversion, a key technology for achieving this antenna.

Beam-forming network characteristics of spatial optical signal processing array antenna for multibeam reception

We have experimentally investigated the basic characteristics of a beam-forming network in a spatial optical signal processing array antenna for multibeam reception. In this experiment, two RF signals, which were simulated multibeam antenna receiving signals from different directions, were separated according to the signal arrival direction in the optical domain. The obtained results generally agreed with calculated values.

Wideband millimeter wave/optical network applications in Japan

This paper describes work on wideband millimeter-wave/optical network applications in Japan, especially projects being pursued at ATR. Results of fundamental transmission experiments demonstrate the feasibility of digital signal transmission at 118 Mbps with a BER of less than 10/sup -6/. In addition, an advanced system considered suitable for future high-speed mobile communications is proposed. This system employs an intelligent multibeam antenna and the direction of each sharp beam can be controlled adaptively. An optical signal processing array antenna is found to be suitable for this system, and several key technologies for system construction are described.

Beam formation by using optical signal processing techniques

We discuss the array antenna beam forming and multibeam operation controlled by an optical processor which performs signal processing by means of Fourier optics. We also give the antenna radiation pattern analysis, antenna system parameter evaluation, as well as a comparison with measured data.

Beam-steering characteristics of a waveguide type optical phased array antenna

der and laser. The fiber is held in Vgrooves and fixed by PbSn soldering. Fig. 2 shows a photograph of typical laser diode module, whose size is 3 mm X 5 mm X 0.8 mm. m To verify an availability of this alignment method, we have measured coupling efficiency between the laser and the fiber of assembled modules. We used multiquantum well 1.3 pm wavelength laser diode and cleaved or cone singlemode fiber for butt joint coupling. The cone fiber has a hemispherical-end with a curvature radius of 30 pm that is formed within 2 1 pm accuracy by micromachining grinding process. Fig. 3 shows a coupling loss distribution for 15 modules using cleaved and cone fiber respectively. Uniform coupling loss has been obtained within 1 dB for cleaved fi-

Optical feed for multibeam microwave array antennas

A new optical feed for transmitting multibeam microwave array antennas is proposed by using spatial Fourier optical processing. The system design is given with consideration of generating overlapping multiple beams. A two-beam experimental optical feed is demonstrated. Two RF signals of 800 MHz and 1 GHz with different phase distributions for feeding to array antennas are obtained and measured spatially.