Tips for designing three bandpass filters

[Calvinckc]

RF Bandpass Filter

Is there any tips for designing three bandpass filters with lumped components ???
They are 50~150MHz, 150~250MHz and 250~860Mhz.
Also the slope is 20dB/decade.

 

[Calvinckc]

Re: RF Bandpass Filter

I designed and simulated the three filters, but it won't work when it is implemented..........could any one suggest some ways or program to design it ??

 

[springf2000]

Re: RF Bandpass Filter

why not use the SAW filter

 

[alexx]

Re: RF Bandpass Filter

Hi Calvinckc

A program for filter design is Filter Solutions from Nuhertz Technologies, L.L.C.
http://www.nuhertz.com

Even if you design a lumped component filter correct you may find that it is not working after building it.
It's hard to say what's problem in your case but generally it can be:

Component tolerances (A capacitor that should be 20 pF, is in fact 23 pF).
Unwanted coupling between components.
Unwanted coupling to the ground plane or shield. (A filter may work good when it is opened but do not work when the cover is on).
High component losses.
Component parasitics. ( **broken link removed** )
Component self resonances and higher modes ( **broken link removed** )

A filter type that offers good performance, in the aspects mentioned above, is the coaxial tubular filter.
http://www.lorch.com/ttubular.html
**broken link removed**

//alexx

 

[VSWR]

Re: RF Bandpass Filter

Post your design files here (zip or RAR them first) and we might help you.

I designed and simulated the three filters, but it won't work when it is implemented..........could any one suggest some ways or program to design it ??