500mhz filter

hi,

the best design method to realize the RF BPF (NOT CAVITY FILTERS)


The specifications:

Passband range: 400MHz-600MHz
Passband Insertion Loss: < -3dB
Passband Return Loss: >-15dB
Attenuation at 10 % away from bandwidth is around -60dB


please help in getting the best design method...



thank you

pole placer with LC technology.

Helical
http://www.neosid.de/DWL/Teil3/Seiten/316.pdf