This paper presents a simple computer model for edge-coupled microstrip line. The model includes the effects of unequal odd/even phase velocities, end-effect capacitance, and loss. The bandpass filter design procedure described herein uses the model to select final element values. Agreement for filters constructed on fused silica in comparison with their computer model is very good. Data are provided for a filter operating over 11.5 to 12.4 GHz. These results are obtained on the first mask and with no bench adjustment.