+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Full Member level 3
    Points: 2,077, Level: 10

    Join Date
    Dec 2007
    Location
    finite space
    Posts
    160
    Helped
    17 / 17
    Points
    2,077
    Level
    10

    why axial ratio changes?

    in simulation, when we suspend the patch over ground plane, axial ratio changes. i need explanation why this happens physically.. thx. Also some way to handle this problem ll be well.

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 5
    Points: 36,491, Level: 46
    flatulent's Avatar
    Join Date
    Jul 2002
    Location
    Middle Earth
    Posts
    4,629
    Helped
    492 / 492
    Points
    36,491
    Level
    46

    Re: why axial ratio changes?

    It may be affected by the size of the ground plane. Try your simulation with a ground plane many times larger than the patch.



    •   AltAdvertisment

        
       

  3. #3
    Full Member level 2
    Points: 2,918, Level: 12
    Achievements:
    7 years registered

    Join Date
    Feb 2008
    Location
    Colorado, USA
    Posts
    128
    Helped
    31 / 31
    Points
    2,918
    Level
    12

    Re: why axial ratio changes?

    no with a patch it should be fine with an infinite ground plane, how are you feeding it are do you have two feeds up through the patch or are they offset feeds? is it RHCP or LHCP? is it two patches or one patch fed with a 90 degree offset?

    let me know,
    Zach



    •   AltAdvertisment

        
       

  4. #4
    Advanced Member level 4
    Points: 10,162, Level: 24
    Achievements:
    7 years registered

    Join Date
    Feb 2007
    Location
    All over the Map.
    Posts
    1,097
    Helped
    218 / 218
    Points
    10,162
    Level
    24

    Re: why axial ratio changes?

    Axial ratio is a function of amplitude balance between the components as well as the phase balance. Disturbing either will effect the axial ratio.



  5. #5
    Full Member level 2
    Points: 2,918, Level: 12
    Achievements:
    7 years registered

    Join Date
    Feb 2008
    Location
    Colorado, USA
    Posts
    128
    Helped
    31 / 31
    Points
    2,918
    Level
    12

    why axial ratio changes?

    I agree that it is and that is why your axial ratio should change consistantly when making the ground plane larger (by the same amount on all sides) should not change your AR with a single patch fed the same now if you have two antennas it might change depending on your setup if you do not have the same ground connecting them and then you do, yes it will change.



    •   AltAdvertisment

        
       

  6. #6
    Full Member level 3
    Points: 2,077, Level: 10

    Join Date
    Dec 2007
    Location
    finite space
    Posts
    160
    Helped
    17 / 17
    Points
    2,077
    Level
    10

    Re: why axial ratio changes?

    my design is a circular patch antenna with one coax feed. with CP about 4 db. without elevation over ground plane. When i elevate( seperate ground plane below patch(with dielectric) 20mm,25mm,30mm etc.) i see that AR changing(in simulation).



--[[ ]]--