Performance Analysis of a 2.45GHZ Digital Beam-forming Antenna for Short-range Wireless Communication

P. Salonen and M. Keskilammi (Finland)


Adaptive antenna, Quantization noise,Radiation pattern optimization, WLAN, RFID.


Spatial filtering using adaptive or smart antennas has emerged as a promising technique to improve the performance of cellular mobile systems. Many radiation parameters of an adaptive antenna, such as antenna gain, beamwidth and sidelobe level, are functions of scan angle or main beam pointing direction. In addition, the digital nature of the control of spatial filtering a quantization error is readily present. This is due to the fact that weights and phase information is provided with the aid of finite wordlength processors. In this paper the radiation pattern degradation of an adaptive antenna due to antenna feed current coefficient quantization is studied. The result will show that the quantization error, even if it small, can degrade the pattern so dramatically making it unacceptable. However, by optimizing the error the desired pattern can be achieved. This means that the error in a single current amplitude might be larger compared with the initial quantization error but the total error to the desired radiation pattern is minimized. In addition this shows very well that with as low number of control bits as four most of the desired radiation patterns can be achieved.

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