Читать книгу Handbook of Microwave Component Measurements - Joel P. Dunsmore - Страница 54

For many applications, the size of 50 Ω microstrip line is not suitable for connections to very large devices. Some common modifications are suspended substrate microstrip line, where the ground plan has been removed some distance from the dielectric. This has the effect of lowering the effective dielectric constant and raising the impedance of the line. In this way, a wider line can be used to connect to a wide component and still maintain a matched impedance. A shielded microstrip line is entirely enclosed (the theoretical models of microstrip lines assume no top shield), and the top metal tends to lower the impedance of the line. This is particularly true for suspended microstrip lines.