using standard courier delivery
A novel multilayer coupler is proposed in this work. With the symmetric traces, the ground plane can be repeated layer by layer. This innovative design achieves vertically stacked coupling without vias or complicated structures. The solution for a set of coupler specifications is non-unique. The designer has the freedom to choose a proper configuration for different applications and fabrication requirements. The design data generated by method of moments provides the guideline for design procedure and tuning. A prototype 3-dB coupler has been simulated and fabricated. The numerical simulation and the experimental measurement show the same performance as a Lange coupler with the same frequency requirements. A prototype stacked bandpass filter has also been built to demonstrate the design procedure. This vertical stack filter system can reduce the circuit footprint size dramatically. Furthermore, this system is also compatible with other conventional size reduction methods. The designer can integrate this multilayer layer stacked filter design with other size reduction methods to achieve an even more compact RF device.