Crosstalk control for microstrip circuits on PCBs at microwave frequencies

Measurements of crosstalk between microstrip lines placed on a set of test circuit boards suggest that very large fraction of the crosstalk at microwave frequencies occurs through lateral signal spreading in the substrate of the test circuit board used. The entire surface areas of the test circuit boards were copper plated except around the top traces of the microstrip lines for circuit isolation. The crosstalk through the air path is very inefficient. The control of crosstalk through the substrate and air path is explored separately with a set of practical and cost-effective techniques.