This paper describes a digital beamforming (DBF) multibeam antenna that incorporates a compact digital signal processor (DSP) engine, and the results of using it in a beamforming experiment receiving a satellite signal in a land-mobile environment. A considerable reduction in the scale of the DSP engine has been achieved by using field programmable gate arrays (FPGA's). To capture a satellite signal arriving from an unknown direction, a two-dimensional (2-D) spatial FFT signal processing provides orthogonal multibeam patterns on the broad side of a planar array antenna. The experimental results demonstrated the features of coarse acquisition and tracking of a signal arrival by selecting the strongest of the beams without assistance from direction finding sensors or microwave phase shifters. The DBF multibeam antenna will provide high-quality communications and increase traffic capacity if it is applied to a high-gain mobile antennas or a multispot-beam base station antennas in cellular or satellite mobile communications.

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This paper discusses a land‐mobile satellite experiment and its results, on a self‐beam steering array antenna implemented by using a digital beam forming (DBF) technique with a compact digital signal processing circuit using ASICs. This antenna allows automatic and open‐loop beam steering toward an unknown signal arrival direction by simple spatial signal processing. Beam‐space maximal‐ratio combining was employed as the steering algorithm. The antenna was mounted on a test van and the basic performance was demonstrated by receiving a signal in the 1.5‐GHz band in a land‐mobile satellite channel with the Japanese ETS‐V satellite. The experiment showed stable beam steering and automatic tracking under real mobile conditions. Reacquisition of the signal arrival after shadowing was also fast enough. Moreover, steering for the direct signal arrival was not affected even with the arrival of a strong, reflected multipath signal. The possibility for optimal combination of multipath signals was demonstrated by multidirectional steering patterns. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(7): 1–13, 1998

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