A Low-Profile Bi-Directional Cavity Antenna with Broadband Impedance Characteristics

Atsushi YAMAMOTO  Hiroshi IWAI  Toshimitsu MATSUYOSHI  Koichi OGAWA  

IEICE TRANSACTIONS on Communications   Vol.E84-B   No.9   pp.2490-2497
Publication Date: 2001/09/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Innovation in Antennas and Propagation for Expanding Radio Systems)
Category: Mobile Antennas
bi-directional radiation pattern,  cavity antenna,  IMT-2000,  picocell base station,  

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A low-profile bi-directional cavity antenna has been developed for the IMT-2000 indoor base stations. The geometrical relationships required for the design of an antenna with broadband impedance characteristics, which are obtained as a superposition of two resonant modes (M-antenna + metal case), are presented. The approximate equations describing the resonant frequencies associated with the two resonant modes are derived. By using the equations, a cavity antenna with dimensions of 120 mm 120 mm 12 mm and a fractional bandwidth of 18.3% (VSWR <2) that meets the IMT-2000 specification can be designed successfully. The proposed design procedure of the antenna is confirmed by the measurements.