Adaptive Beamforming of ESPAR Antenna Based on Steepest Gradient Algorithm

Yukihiro KAMIYA
Takashi OHIRA

IEICE TRANSACTIONS on Communications   Vol.E84-B    No.7    pp.1790-1800
Publication Date: 2001/07/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Adaptive Array Antenna Techniques for Advanced Wireless Communications)
Category: Beamformer Techniques
gradient algorithm,  adaptive beamforming,  mobile user terminal,  interference reduction,  low complexity,  

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Conventional adaptive array antenna processing must access signals on all of the array antenna elements. However, because the low-cost electronically steerable passive array radiator (ESPAR) antenna only has a single-port output, all of the signals on the antenna elements cannot be observed. In this paper, a technique for adaptively controlling the loaded reactances on the passive radiators, thus forming both beam and nulls, is presented for the ESPAR antenna. The adaptive algorithm is based on the steepest gradient theory, where the reactances are sequentially perturbed to determine the gradient vector. Simulations show that the ESPAR antenna can be adaptive. The statistical performance of the output SIR of the ESPAR antenna is also given.