== Designing a Stepped Impedance Microstrip Lowpass Filter ==
[[File:RF58.png|thumb|500px|The top view of layout of the Stepped Impedance Mirostrip Lowpass filter.]]
A distributed microstrip version of the above ladder LC filter can be realized using consecutive low- and high-impedance line segments. It is well known that short segments of low- and high-impedance [[Transmission Lines|transmission lines]] behave like capacitive and inductive elements, respectively. Therefore, you will need four low-Z0 microstrip segments to replace the capacitors C1, C2, C3 and C4, and three high-Z0 microstrip segments to replace the inductors L1, L2 and L3. The transformations are based on the following equations:
for capacitors. Here Z<sub>high</sub> and Z<sub>low</sub> are the high and low characteristic impedances of the narrow and wide microstrip segments, respectively, and R<sub>0</sub> is the reference impedance of the filter.
[[File:RF54.png|thumb|600px|The schematic of a Stepped Impedance Microstrip Lowpass filter.]]
For this project, you will use 0.5mm-wide and 5mm-wide microstrip lines to realize Z<sub>high</sub> and Z<sub>low</sub>, respectively. As you found earlier, these lines provide approximately 102Ω and 30Ω impedances, respectively. Using the above transformations, the following table for the segment lengths is obtained:
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[[File:RF58RF54.png|thumb|600px|The top view schematic of layout of the a Stepped Impedance Mirostrip Microstrip Lowpass filter.]]
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== Adding the Microstrip Step Discontinuity Models ==