New Microstrip Transmission Lines for Microwave Integrated Circuits

The paper discusses the properties of new microstrip transmission lines using a slot in the ground-plane. These lines have high characteristic impedance and their attenuation and frequency dispersion as well are small. A very tightly coupled cross-section of microstrip lines may be constructed using the new structures of coupled-lines. The numerical computations of the characteristic impedance and phase velocity of the single-and coupled-lines are given. In the variational method an approximated functions of the charge density on the strip and the potential in the slot in order to fulfil of the complicated boundary conditions caused by the slot and the multi-layered dielectric are evaluated. Then the potential distribution on the strip and the capacitance are computed using the variational expression in the Fourier-transformed domain. The applications of the new microstrip lines in MIC and some experimental results are presented.