What filter type should I select for such bandpass filter design?
I would like to design a bandpass filter. Center frequency is 400MHz and bandwidth is 40MHz. Insertion loss will not be greater than 1dB. Rejection will be 50dB in the rejection band, 0-360MHz and 465-1000MHz. What is the best suitable filter type (LC, Combline, Interdigital....) I can realize this filter in as small package as possible?
Your help will be appreciated.
LC type is the only option you have all others are to bulky due to low frequency (400MHz) and high PCB cost since you demand a low insertion loss....
what order and topology of filter do you guess that I can achieve these specs?
What about cascading a low pass and high pass filters as the ratio 40/400 seems to be little bit large.
I think achieving both reject band and insertion loss at the passband is difficult in lowpass+ highpass filter arrangement. Size, as you said, will be big too.
What is the max. power passes through the filter ?
< 1W : use dielectric filter, small, cheap and easy to implement.
Rogerynt
use lc filter. Easy to design & assemble.
Do you know any off-the-shelf dielectric filters which work around 400MHz? How I will choose these resonators to build a filter meeting these specifications?
Thanks rogerynt
try Helical filter TT6843A-400.25M-2M http://www.temwell.com.tw/main.htm
I just looked at the insertion loss plot of the helical filter you suggested me. That helical filter doesn't give me the rejection I need unfortunatelly.
http://www.tonnesoftware.com/helical.html
hi.
To design a Band pass filter with lumped element you can use capacitive coupling method. For this u can refer Mathai's Book.