+ Post New Thread
Results 1 to 10 of 10
  1. #1
    Newbie level 6
    Points: 981, Level: 7

    Join Date
    Jan 2011
    Posts
    12
    Helped
    1 / 1
    Points
    981
    Level
    7

    Bandpass filter design

    Hi,

    I am using Microwave office to design filters. I am designing bandpass filters in the frequency range 160 MHz +/-25 MHz bandwidth and also 160 MHz +/-0.25 MHz. Second frequency range is 1000 MHz +/- 250 MHz and also 1000 MHz +/- 12.5 MHz.
    1. Rejection level is 50 dB min away from 3 dB bandwidth.
    2. Phase between different channels are with in +/- 2 deg. (each channel have these filter bands and like wise 3 channels)

    Kindly suggest the suitable filter type for achieving these specs.

  2. #2
    Full Member level 4
    Points: 3,992, Level: 14

    Join Date
    Jun 2006
    Location
    Pennsylvania, USA
    Posts
    200
    Helped
    28 / 28
    Points
    3,992
    Level
    14

    Re: Bandpass filter design

    Look at what others have done. Companies such as Lorch (www.lorch.com), K&L (http://www.klfilterwizard.com) & Mini-Circuits has invested heavily in "Filter Selection Tools".



    •   AltAdvertisement

        
       

  3. #3
    Junior Member level 3
    Points: 1,556, Level: 9
    Achievements:
    7 years registered

    Join Date
    Dec 2011
    Posts
    28
    Helped
    6 / 6
    Points
    1,556
    Level
    9

    Re: Bandpass filter design

    Hi,
    Since you are using Microwave Office (MWO), you can check "Ifilter wizard" of MWO. However, availability of this wizard depends on your licence options.



  4. #4
    Super Moderator
    Points: 52,937, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,948
    Helped
    2580 / 2580
    Points
    52,937
    Level
    56

    Re: Bandpass filter design

    A series LC, or an LC tank, might suit (at lower frequencies anyway).

    Play with the L:C ratio, because that affects Q, and bandwidth. For instance, increase L by multiples of 10, decrease C by multiples of 10.



    •   AltAdvertisement

        
       

  5. #5
    Advanced Member level 5
    Points: 30,418, Level: 42
    BigBoss's Avatar
    Join Date
    Nov 2001
    Location
    Turkey
    Posts
    4,458
    Helped
    1340 / 1340
    Points
    30,418
    Level
    42

    Re: Bandpass filter design

    Quote Originally Posted by m11vajju View Post
    Hi,

    I am using Microwave office to design filters. I am designing bandpass filters in the frequency range 160 MHz +/-25 MHz bandwidth and also 160 MHz +/-0.25 MHz. Second frequency range is 1000 MHz +/- 250 MHz and also 1000 MHz +/- 12.5 MHz.
    1. Rejection level is 50 dB min away from 3 dB bandwidth.
    2. Phase between different channels are with in +/- 2 deg. (each channel have these filter bands and like wise 3 channels)

    Kindly suggest the suitable filter type for achieving these specs.
    What is your offset frequency for rejection of 50 dB ?



  6. #6
    Newbie level 6
    Points: 981, Level: 7

    Join Date
    Jan 2011
    Posts
    12
    Helped
    1 / 1
    Points
    981
    Level
    7

    Re: Bandpass filter design

    20% away from edges.



  7. #7
    Advanced Member level 5
    Points: 14,152, Level: 28

    Join Date
    Apr 2014
    Posts
    2,215
    Helped
    883 / 883
    Points
    14,152
    Level
    28

    Re: Bandpass filter design

    Quote Originally Posted by m11vajju View Post
    160 MHz +/-0.25 MHz
    0.15% bandwidth is tough - what is your acceptable insertion loss?



    •   AltAdvertisement

        
       

  8. #8
    Newbie level 6
    Points: 981, Level: 7

    Join Date
    Jan 2011
    Posts
    12
    Helped
    1 / 1
    Points
    981
    Level
    7

    Re: Bandpass filter design

    We have an amplifier to compensate for the Insertion loss. Insertion Loss can be around 5dB.



  9. #9
    Newbie level 6
    Points: 981, Level: 7

    Join Date
    Jan 2011
    Posts
    12
    Helped
    1 / 1
    Points
    981
    Level
    7

    Re: Bandpass filter design

    Quote Originally Posted by volker@muehlhaus View Post
    0.15% bandwidth is tough - what is your acceptable insertion loss?
    Insertion Loss acceptable is around 5dB.



  10. #10
    Advanced Member level 5
    Points: 14,152, Level: 28

    Join Date
    Apr 2014
    Posts
    2,215
    Helped
    883 / 883
    Points
    14,152
    Level
    28

    Re: Bandpass filter design

    Quote Originally Posted by m11vajju View Post
    Insertion Loss acceptable is around 5dB.
    Then have a look at these coax cavity filter designs, as an example what physical size to expect:
    http://www.ik-telecom.com/hamradio/2m/filters/eng/



--[[ ]]--