Tunable Composite Right/Left-Handed Delay Line with Large Group Delay for an FMCW Radar Transmitter

  • Park, Yong-Min (Dept. of Radio Science and Engineering, Chungnam National University) ;
  • Ki, Dong-Wook (Dept. of Radio Science and Engineering, Chungnam National University)
  • Received : 2012.03.07
  • Accepted : 2012.05.04
  • Published : 2012.06.30


This paper presents a tunable composite right/left-handed (CRLH) delay line for a delay line discriminator that linearizes modulated frequency sweep in a frequency modulated continuous wave (FMCW) radar transmitter. The tunable delay line consists of 8 cascaded unit cells with series varactor diodes and shunt inductors. The reverse bias voltage of the varactor diode controlled the group delay through its junction capacitance. The measured results demonstrate a group delay of 8.12 ns and an insertion loss of 4.5 dB at 250 MHz, while a control voltage can be used to adjust the group delay by approximately 15 ns. A group delay per unit cell of approximately 1 ns was obtained, which is very large when compared with previously published results. This group delay can be used effectively in FMCW radar transmitters.



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