In this letter, a wideband 180° phase shifter using a parallel-coupled three-line is demonstrated. The proposed phase shifter consists of a shorted coupled line and transmission line with shorted stubs. The bandwidth of the phase shifter is increased by a high coupling factor of the coupled line. When considering a coupling factor of 1, the bandwidth is infinite and the phase error is zero. Therefore, we adopted a parallel-coupled three-line to ensure a high coupling factor. Given a limited coupling factor, the transmission line impedance is optimized for the widest bandwidth of the return loss. The designed 180° phase shifter exhibits a return loss of less than -15 dB and a maximum phase error of less than 5° in the 1.14-2.79-GHz range and its fractional bandwidth is 83.9%.
Bibliographical noteFunding Information:
Manuscript received August 26, 2018; revised November 7, 2018; accepted December 5, 2018. Date of publication January 1, 2019; date of current version February 14, 2019. This work was supported by the National Research Foundation (NRF) grant funded by the Korea government (MSIT) (No. 2017R1A1A1A05001134). (Corresponding author: Byung-Wook Min.) The authors are with the Department of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, South Korea (e-mail: firstname.lastname@example.org). Digital Object Identifier 10.1109/LMWC.2018.2886469 Fig. 1. Schematic of (a) proposed phase shifter and (b) shorted parallel-coupled three-line (path 2) and its equivalent circuit.
This work was supported by the National Research Foundation (NRF) grant funded by the Korea government (MSIT) (No. 2017R1A1A1A05001134)
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All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Electrical and Electronic Engineering