Investigation on a Multi-Band Inverted-F Antenna Sharing Only One Shorting Strip among Multiple Branch Elements

Tuan Hung NGUYEN  Takashi OKI  Hiroshi SATO  Yoshio KOYANAGI  Hisashi MORISHITA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.7   pp.1302-1315
Publication Date: 2015/07/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.1302
Type of Manuscript: PAPER
Category: Antennas and Propagation
Keyword: 
multi-band,  inverted-F antenna,  small antenna,  handset antenna,  low-profile,  infinite ground plane,  

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Summary: 
This paper presents the detailed investigations on a simple multi-band method that allows inverted-F antennas (IFAs) to achieve good impedance matching in many different frequency bands. The impressive simplicity of the method arises from its sharing of a shorting strip among multiple branch elements to simultaneously generate independent resonant modes at arbitrary frequencies. Our simulation and measurement results clarify that, by adjusting the number of branch elements and their lengths, it is very easy to control both the total number of resonant modes and the position of each resonant frequency with impedance matching improved concurrently by adjusting properly the distance ds between the feeding and shorting points. The effectiveness of the multi-band method is verified in antenna miniaturization designs, not only in the case of handset antenna, but also in the design upon an infinite ground plane. Antenna performance and operation principles of proposed multi-band models in each case are analyzed and discussed in detail.