A frequency adjustable double lorentz CRLH transmission line using DGS

In this paper, a double lorentz composite right left handed(DL-CRLH) transmission line is designed using defected ground structure (DGS) and varactor diodes. Previously, the diode has been adopted only selectively for one of parallel or series resonators, and the balanced frequency as well as triple band frequencies were fixed. However in the proposed DL-CRLH transmission line, the balanced frequency, where the resonant frequencies of the series-connected parallel resonator and shunt-connected series resonator are the same, is adjustable. In addition, the triple band frequencies are controlled, too. The measured balanced frequency varies between 3.42-4.8GHz according to the controlled bias voltage. Under the same bias condition for the balanced frequency, the adjusted frequencies are 2.22-2.77GHz, 3.7-5.2GHz, 7.32-8.23GHz, 3.42-4.8GHz, and 4.44-5.92GHz for the conditions that ßd=+0.5π, -0.5π, 2nd +0.5π, ω∞, and ω_o, respectively.