A transformer of one-third wavelength in two sections - for a frequency and its first harmonic

• Published in: IEEE microwave and wireless components letters Vol. 12; no. 1; pp. 22 - 23
• Main Authors: Chow, Y.L., Wan, K.L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2002; Institute of Electrical and Electronics Engineers
• Subjects: Antenna arrays; Applied sciences; Circuit properties; Circuits; Dual band; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Frequency; GSM; Harmonics; Impedance; Mathematical analysis; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Nonlinear equations; Personal communication networks; Power transmission lines; Reflection; Transformers; Transforms; Transmission lines; Wavelengths; Microwave circuit; Transmission line; Frequency doubler; Fundamental frequency
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/7260.975723

The quarter-wave transformer transforms in one frequency f/sub 0/, but not its first harmonic 2f/sub 0/. The transform in 2f/sub 0/ is needed in a dual-band operation of GSM and PCS. This requirement can be fulfilled in a two line-sections of 1/6 wavelengths each, adding to 1/3 wavelengths for the total transformer length in the lower band centering at f/sub 0/ (fundamental), or 2/3 wavelengths in the upper band centering at 2f/sub 0/ (1st harmonic). The 1/3-wave transformer is analytically inexact but effectively exact for engineering applications. For example, for impedance transforms of K = 4, the inexactness gives a reflection of |/spl Gamma/| = 0.013.