High Level Miniaturization for Quadrature Hybrid Directional Coupler


This application note demonstrates how compact quadrilateral (branch-line) hybrid directional couplers can be designed efficiently using the WIPL-D Pro CAD. The designs are simulated by using the traditionally fast WIPL-D full wave 3D EM simulation.

The CAD tool enables easy and fast modeling of arbitrary structures using numerous built-in primitives and manipulations. In-house code for automatic meshing into quadrilateral patches, especially optimized for WIPL-D HOBF kernel, is employed.

The WIPL-D kernel enables fast and accurate simulation of PCB structures on inexpensive machines. The traditional coupler realized in microstrip technology is simulated in just a couple of seconds per frequency. As a result of a miniaturization, its size was almost halved. However, the miniaturization requires a careful design of artificial transmission lines with numerous fine details. EM simulation of such a device is much more demanding as it requires a large number of unknowns, but the high efficiency of the simulations is preserved as it takes only a couple of minutes per frequency point.

All the details significant for EM simulation such as losses, finite metallization thickness, finite size of the substrate and the ground conductor, location of the feeding point etc. are included in the model. The results presented include return loss at all of the ports, power division between the output ports, isolation between the input ports and finally the phases of the signals at the two output ports.

Section: Microwave  Circuits

For full version of the document, please check the following pdf.