Microwave multilayer
I would like to know if it's possible to have a microstrip on a layer and another on another and make the wave travel from the micro strip underneath to the one above? and should i have a ground plane sandwiched between the two?
I have tried this, but it doesn't seem to be working great.
Thank you in advance.
I think if the Bottom(lowest one) layer has been defined as GND layer, the second Strip Line will behave as Microstrip Line.
Try to cancel this layer ( GND ),it should work..
Otherwise it's no microstrip.
Which problems do you experience?
The via probably involves some impedance discontinuity if via diameter and antipad are not dimensioned well considered.
I had an S11 of -6dB and S21 of -2.5dB.
So yes my problem is impedance discontinuity, and i don't know how to calculate my via diameters. i have just put a random value and tried to change it to see how it influenced my S parameters.
Is there any litterature you can recommend to me about this please? i'd be grateful.
Empirical adjustment of dimensions isn't bad. A time domain representation of S11 (TDR) can help to "see" the required correction.
For good wide band matching, you should try to achieve more smooth width variation, possibly two small bias instead of one bigger.
I agree with FvM, try to keep the width between line and via, by using one large via or two smaller vias side by side. The parameter for tweaking S11 is then the diameter of the cutout in ground.
yes it is possible. Usually it is a microstrip layer on the back side, a via thru the middle of the board, and a microstrip layer on the top side. And trhe dimensions of the via and ground holes are critical.
It is much more troublesome to have a structure in the middle of the board....like a stripline buried layer transitioning to a top microstrip layer. I personally have never had any luck getting that to work.