Broadband composite right/left-handed coplanar waveguide power splitters with arbitrary phase responses and balun and antenna applications

• Published in: IEEE transactions on antennas and propagation Vol. 54; no. 1; pp. 243 - 250
• Main Authors: MAO, Shau-Gang, CHUEH, Yu-Zhi
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna; Antenna measurements; Antennas; Applied sciences; Baluns; Bandwidth; Broadband antennas; Circuit simulation; composite right/left-handed coplanar waveguide (CRLH CPW); Coplanar waveguides; Delay; Equivalent circuits; Exact sciences and technology; Impedance matching; Loop antennas; Loss measurement; Phase error; Phase shift; power splitter; Power splitters; Radiocommunications; Telecommunications; Telecommunications and information theory; transition; Waveguide transitions; Performance evaluation; Return loss; Lossy medium; Balun; Coplanar line; transition; power splitter; Power divider; Antenna gain; composite right/left-handed coplanar waveguide (CRLH CPW); Wide band; Simulation; Insertion loss; Equivalent circuit; Radiation pattern; Phase delay; Coplanar waveguides; Miniaturization; Delay line; T shape; Loop antenna; Antenna
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2005.861574

This study presents novel coplanar waveguide (CPW) power splitters comprising a CPW T-junction with outputs attached to phase-adjusting circuits, i.e., the composite right/left-handed (CRLH) CPW and the conventional CPW, to achieve a constant phase difference with arbitrary value over a wide bandwidth. To demonstrate the proposed technique, a 180/spl deg/ CRLH CPW power splitter with a phase error of less than 10/spl deg/ and a magnitude difference of below 1.5 dB within 2.4 to 5.22 GHz is experimentally demonstrated. Compared with the conventional 180/spl deg/ delay-line power splitter, the proposed structure possesses not only superior phase and magnitude performances but also a 37% size reduction. The equivalent circuit of the CRLH CPW, which represents the left-handed (LH), right-handed (RH), and lossy characteristics, is constructed and the results obtained are in good agreement with the full-wave simulation and measurement. Applications involving the wideband coplanar waveguide-to-coplanar stripline (CPW-to-CPS) transition and the tapered loop antenna are presented to stress the practicality of the 180/spl deg/ CRLH CPW power splitter. The 3-dB insertion loss bandwidth is measured as 98% for the case of a back-to-back CPW-to-CPS transition. The tapered loop antenna fed by the proposed transition achieves a measured 10-dB return loss bandwidth of 114%, and shows similar radiation patterns and 6-9 dBi antenna gain in its operating band.