Multiband Automatic Tunable Antenna System Based on the Received Power of a Probe

Makoto HIGAKI  Shuichi OBAYASHI  Hiroki SHOKI  

IEICE TRANSACTIONS on Communications   Vol.E99-B    No.11    pp.2390-2398
Publication Date: 2016/11/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3350
Type of Manuscript: PAPER
Category: Antennas and Propagation
automatic tuning,  multiband antenna,  small antenna,  

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This paper proposes a multiband automatic tunable antenna system for wide frequency bands of 704-2690MHz for cellular wireless communication systems. The proposed system controls variable capacitors connected between the antenna and a transmitter based on the received power of a probe. Locating the probe near the tip of the antenna enables frequency-a operation. The antenna is a multiband two-arm monopole antenna printed on a 60mm × 10mm area of a 60mm × 100mm FR-4 printed circuit board (PCB). The probe is a small dipole antenna capacitively coupled with the antenna. Fine-tuning based on simple hill-climbing optimization compensates the mismatch due to the surroundings, e.g., a user's hand/head or desk assuming channel-informed rough-tuning beforehand. A prototype consisting of varicap diodes and some other devices demonstrates automatic tunability.