The Transmission Characteristics Of Microstrip Lines, The Shielding Box

Microstrip line is being widely used as one of the most common transmission line in MMIC and MIC nowadays, and the study of microstrip line is very important in the design of microwave integrated-circuit. And for the reason of electromagnetic shielding or the reinforcement of material strength, the microstrip line is packaged in a metal box ordinarily. And the shielded box would affect the characteristics of microstrip line, sometimes the shielded box even make the circuit can not work. So, it is very important to study the influence of the shielding box on the characteristics of the microstrip lines.The spectral-domain method which based on Fourier transform is an accurate and powerful method in the analysis of the planar transmission line. By transforming the integral equations into algebra equations, the spectral-domain method simplified the analysis while the numerical results keep a high accuracy.By using Galerkin's method in the spectral domain the shielded microstrip lines have been analyzed in this article, and the numerical results show a good agreement with the data of other papers and the results of HFSS. And the numerical results of the propagation constant also show a good agreement with the Experimental results.At the end of the article, the influence of the shielding box on the characteristics of microstrip had been analyzed.