need help on design a filter

for example, I want to design a filter that pass 2.5GHz signal, but filter out 2.2GHz. So at the output of the filter, 2.5GHz signal will be much much larger than 2.2GHz signal.
I tried bandpass and high pass filter, but the antenuation at 2.2GHz is not enough.
Is there any other way to implement it?

Thanks

Your best bet is a bandpass type. You will have to use a large number of poles (or resonators) to get the attenuation you want only a few percent away in bandwidth.

A much more expensive way is to down convert the whole frequency range to a lower frequency and band pass filter at the lower frequecy where the separation is a larger percent of the center frequency. Then, if necessary, upcovert using the same local oscillator.

How much rejection do you need at 2.2 GHz?

Please try a narrow band pass filter with T-network

at least -80 dB at 2.2GHz
bandpass is the way to go i thought about this too, but is there a way to use least number of components?

IT depends to the bandwidth of filters, you should use filters with high Q resonators for example DR filters.

hi.
for designing a filter matlab is the best tool.plz go n read out the tutorials of matlab regarding to filter design.hope u find ur result
thanks

Added after 1 minutes:

hi.
for designing a filter matlab is the best tool.plz go n read out the tutorials of matlab regarding to filter design.hope u find ur result
thanks

I am not sure whether are you using Lump element to design your filter, if you are, you must take note of the Self-resonace frequency (SRF) of the lump element. If your lump element SRF is very low, perhap that may cause you some problem. Usually, the higher the value you use for your lump element, the lower its SRF, which may fall within the frequency of your interest, hence affect the performance of your filter.