A Simple Design Method of the Planar Butler Matrix Using Thin Dielectric Substrate Metalized Both Side

Yoji ISOTA  Osami ISHIDA  Fumio TAKEDA  

IEICE TRANSACTIONS on Electronics   Vol.E86-C   No.2   pp.162-168
Publication Date: 2003/02/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Circuit and Device Technology for High-Speed Wireless Communication)
Category: Passive (Feeder)
Butler matrix,  multi beam antenna,  adaptive array antenna,  beam forming network,  

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Adaptive antenna is a promising to increase the spectral efficiency of mobile radio systems. We developed a compact, cost effective planar Butler Matrix as a beam forming network of a multi beam antenna. This circuit consists of a thin substrate that the conductor attaches to both sides, and two thick substrates that the ground conductor attaches to one side. In this circuit, coupling by crossover causes amplitude and phase error of the Butler Matrix. By narrowing the strip width of the crossover, crossover coupling can be suppressed 10 dB. The measurement results of the experimental 88 Butler Matrix were 0.75 dB amplitude deviation, 9.5 degree phase deviation and VSWR of less than 1.15 within the relative bandwidth of 10% at 900 MHz band.