Compact Directional Coupler for Centimeter and Millimeter Wavelength Ranges

In this paper the compact directional couplers for centimeter and millimeter frequency bands are investigated. Using the NI-AWR Design Environment software, four layouts of miniaturized couplers were synthesized at the central frequencies of 1, 10, 20 and 30 GHz, which dimensions are smaller by 77.75%, 58.8%, 48.4% and 49.4%, respectively, in comparison to the standard designs. Miniaturization was carried out based on equivalent replacement of quarter-wave segments with low-pass filters of the 3rd order.