Building a 4 poles filter

[GGMM]

Hello,

I have assembled 2 filters 2 poles to make one. (Filter 45MHZ 15Khz band filter ref: 45R15AZ)
I have an interesting curve with my nanovna on my homebuild , but I would like to improve the center of the curve to try to have a dish.
What is your best schematic of association of these 2 filters to have a dish in the center
Thank you

 

[danadak]

"Dish", a flat top ? Or equaripple Cheby ?

Your link takes one to -





Regards, Dana.,

 

[GGMM]

Hello,
i have found a schematic to try
yes i want a flat top from 44.992 to 45.008MHZ for exemple
cdt

 

[danadak]

Here is a design tool.

https://rf-tools.com/lc-filter/

Do you have the crystal elements ? The schematic you show is probably
8'th order or higher due to them.

You also do not give all the specs (including loss) needed -

Does it have to be linear phase ?


Regards, Dana.

 

[kellys_eye]

Why a pronounced 'dish' requirement? This isn't 'good' for any reason I can think of when designing filters.....

 

[danadak]

I presume this is the end application ?

https://ac0c.com/attachments/ac0c_Intro_to_Roofing_Filters__cadxa_6_oct_2011.pdf


Regards, Dana.