Looking for Combline filter design schematic

COMBLINE FILTER

I want to design combline filter in microstrip form and in L band(2-4GHz).


I want to see the shematic of some practical design (please send me if
any pictures are available) and I want to know how the capacitors of
this type of filter (in microstrip form and in L band (2 GHz))are
designed (I can't find any practical design in the internet and my only
available referense is internet)

mail: cryptographer111@yahoo.com



Best regards


Nima Azadi

Re: COMBLINE FILTER

Hi,
I suggest you go thru' the application notes of some of the RF IC manufacturers and also try to contact some FAE's. I know it the best way. I had got significant help from MAXIM for GPS ICs.
brmadhukar

Re: COMBLINE FILTER

you can read microstrip lines(gupta)

Re: COMBLINE FILTER

Hi;
ALso use a microwave analysis and design software.

Re: COMBLINE FILTER

HI mate,

I have designed a lot of these filters in the past. The only problem arises when you are trying to decide on the topology of the design i.e. microstrip or suspended substrate depending on the sort of applications. I dont know what tpe of Q factors you want to achieve. Please specify this and I will be able to guide you in the right direction.

Another problem is that not many people have worked on this in the past as compared to other types of filters because of its lossy nature and also strong coupling. I was able to design quite a few for very specific applications. I designed one in microstrip form but was terribly lossy because of the capacitors I used. However, if you use suspended substrate stripline configuration you can construct a capacitor by bringing the ground plane close to the signal layer at the end of the resonator. Plus you need to form some kind of impedance inverters at the ends.

You might want to consult the following book.

Theory and design of microwave filters by Ian Charles Hunter, who I have worked with in the past. This book has a whole section dedicated to combline filters. We have developed a lot of combline filters using various topologies.

Please send me an email on efy8ks@leeds.ac.uk and I will be able to help you out.