Complex modes in a compacted meandered synthetic quasi-TEM line

This paper investigates the dispersion characteristics of the compacted meandered synthetic quasi- TEM line with area totaling 50 x 25 mm₂. The quasi-TEM line, or the so-called complementary-conducting-strips (CCS) transmission line (TL), is formed by a square patch with two connecting arms in the top metal layer and a complementary meshed, two-dimensional, periodical ground plane. Two-port scattering analyses exhibit two stophands in the CCS TL. The matrix-pencil method is applied to extract the modal behavior and demonstrates that the complex-mode pairs exist in the stophand of the CCS TL. For the first time, we may analyze the dispersion characteristics of the meandered transmission line and adequately explain the formation of the stophand of the CCS TL.