Lumped elements to distributed elements

[rf997]

Hello, I want to design a notch filter at 3.7 ghz frequency. When I design the circuit with lumped elements, some capacitor and inductor values are too small. So I want to replace these elements with microstrip lines. How can I do that?

 

[BigBoss]

Rogers Duroid 6006, 0.8mm Height, 35um Copper Clad

 

[rf997]

Rogers Duroid 6006, 0.8mm Height, 35um Copper Clad
View attachment 185752
View attachment 185755

The element thicknesses here are very thin. Is there a different design style for production?

 

[D.A.(Tony)Stewart]

use FR4 subst. for a stiffener.

 

[BigBoss]

The element thicknesses here are very thin. Is there a different design style for production?

0.8mm is not very thin but I have repeated this design for Rogers 6006 1.27mm ( standard thickness )

 

[biff44]

Hello, I want to design a notch filter at 3.7 ghz frequency. When I design the circuit with lumped elements, some capacitor and inductor values are too small. So I want to replace these elements with microstrip lines. How can I do that?

well, one way is to have open circuited stubs that are physically quarter wave at 3.7 GHz. that insures the notch is at 3.7 GHz, since an open circuited line with a quarter wave length looks like a short circuit at its input.

you can control the width of the open circuited line for bigger or smaller notch bandwidth. and you can lead in and lead out of the stub with non 50 ohm lengths, and vary their impedance and length to get a bit of a better match.

but since 3.7 GHz is getting fairly high, parasitic effects will shift the actual notch frequency a little lower, so expect that OR simulate the discontinuiteis at the open circuit end (fringing capacitance) or the T junction where the stub meets the main line.