Coplanar waveguide to Microstip Line
From the material I have read so far, I understand that a coplanar waveguide can be treated as a microstrip line only beyond a certain "gap" i.e separation between the trace and the ground plane. My question is how to calculate or find out the gap and/or what is the minimum gap that defines whether the assumption of microstrip line is correct or not.
PS: This is related to a Test board I am working on that has baluns on it which I am simulating in ADS momentum. The above question is for my hand calculations
ThanK you
Samkeet
Hi Samkeet,
If the "gap" from your trace to the ground plane is more than 2 times the width of the trace, you can consider it as microstrip. This is a rule of thumb only.
If you want to know more accurately, one way you can find out is to use a CPW characteristic impedance calculator and sweep, from 0.5*Width to 3*Width, the separation from trace to ground plane. You should be able to find the minimum gap required to consider your structure as microstrip.
Hope this helps,
Microwave123
Hi Microwave123,
Thank you so much for the advice. In my board, I am considering gap as 2 times the trace width so I think I can go with the rule of thumb. If you dont mind I want to ask you this question also:
1. How do I simulate the cpw in ADS momentum, my concern is the substrate formation. Please hint me if you have some idea. Thanks again
Samkeet