Performance Evaluation for RF-Combining Diversity Antenna Configured with Variable Capacitors

Hiroya TANAKA
Jun-ichi TAKADA
Ichirou IDA
Yasuyuki OISHI

Publication
IEICE TRANSACTIONS on Electronics   Vol.E89-C    No.4    pp.488-494
Publication Date: 2006/04/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.4.488
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced RF Technologies for Compact Wireless Equipment and Mobile Phones)
Category: 
Keyword: 
mobile systems,  adaptive array antennas,  diversity antennas,  variable capacitor,  RF-combining diversity antennas,  perturbation method,  steepest gradient method,  

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Summary: 
An RF adaptive array antenna (RF-AAA) configured with variable capacitors is proposed. This antenna system can control the power combining ratio and phase value of received signals. In this paper, we focus on the diversity effects of RF-AAA. First, we show the design methodology of the combiner circuit to realize the effective combining. Second, the perturbation method and the steepest gradient method are compared for the optimization algorithms to provide fast convergence and suboptimum solutions among the variable circuit constants. Finally, in simulation, we show the RF-AAA can achieve diversity antenna gains of 7.7 dB, 10.9 dB and 12.6 dB for 2-branch, 3-branch and 4-branch configuration, respectively, which have higher performance than the selection combining.