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Ultrabroadband balun with 1:4 impedance transformation ratio using transmission‐line transformers
Author(s) -
Lee H.,
Gu J.,
Kwon J.,
Seo M.,
Ham J.,
Kim H.,
Yang Y.
Publication year - 2014
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.28518
Subject(s) - balun , transformer , impedance matching , transmission line , insertion loss , electrical engineering , electrical impedance , electric power transmission , return loss , microwave , standing wave ratio , materials science , electronic engineering , engineering , telecommunications , voltage , microstrip antenna , antenna (radio)
This article presents an ultrabroadband balun with 1:4 impedance transformation ratio using transmission‐line transformers. The proposed ultrabroadband balun consists of one 1:1 transmission‐line transformer as a balun and two 1:4 transmission‐line transformers for impedance transformation. Each transmission‐line transformer is based on a coaxial line, which is wound around a ferrite core to extend the bandwidth to the lower frequency region. Experimentally optimized offset transmission lines are used to compensate for the phase imbalance characteristics at the high frequency band. The implemented ultrabroadband balun operates from 300 kHz to 400 MHz with a return loss of below 12 dB and an insertion loss of less than 1 dB. The magnitude and phase imbalance for the balanced signal output are both less than 0.5 dB and 2.0°, respectively. An outstanding relative bandwidth (the ratio of the highest frequency to the lowest frequency in the operational band) of 1330 was achieved. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1974–1978, 2014