It is common for RF applications using PCB technology at microwave frequencies to use microstrip circuit structures. However, as the frequency increases, at higher microwave frequencies and millimeter-wave (mmWave) frequencies, there are increased RF performance issues for the RF designer to consider. In theory, the Grounded Coplanar Waveguide (GCPW) circuit structure addresses many of the mmWave design concerns. Although, in practice, there are multiple influences which can impact mmWave RF performance due to PCB manufacturing and the RF performance of GCPW is more impacted than microstrip.
This presentation will give an overview of the basic RF performance of microstrip and GCPW, in the range of microwave and mmWave frequencies. Following the overview, several topics will be explained which are related to mmWave design concerns with an emphasis on several common PCB fabrication processes which can influence RF performance of microstrip and GCPW differently. Measured RF data up to 80+ GHz will be shown to illustrate many of the concepts discussed.