Need help in designing interdigital filters

Hi all,
I have to design 4th order Inter digital filter. Give center frequency 2 GHz and pass bandwidth is 1 GHz. passband return loss is 20 dB. Anyone help me to design this filter.
and one question .. Is it possible to have negative even or odd mode impedance?
thanks.

You should do your project by yourself. Someone in this forum maybe share ideas with you.

you can not have negative even of odd mode impedances.

thanks mate