Power Distribution Networks in Multilayer LTCC for Microwave Applications

Divider networks are key modules for feeding antenna elements in microwave applications like RADAR sensors for space (SAR: Synthetic Aperture Radar, remote sensing of earth), avionic, military, automotive, ISM bands and others. The RF power at the input port is distributed equally to an arbitrary number of output ports. The most important specifications of these divider networks are the phase and amplitude balance stability at the output ports, the isolation between different output ports as well as the VSWR. Multilayer LTCC has several advantages in comparison to standard microwave boards: Divider network and patch antenna array can be fabricated in the same module, separated by an inner ground mesh; large divider networks can either be on the top or bottom of the substrates in microstrip configuration or in inner layers as shielded triplate waveguides. The main component of such a circuitry is the Wilkinson divider, which splits the input power equally to two output ports. With a cascade of Wilkinson dividers an arbitrary 1:n power distribution network can be realized. Such circuits have been designed, fabricated and evaluated by the authors.