A new class of miniature quadrature couplers for MIC and MMIC applications

A new class of miniature quadrature couplers suitable for microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) are presented. The proposed couplers have some advantages compared to conventional types, such as smaller size, no harmonic response, and wide stop-band characteristics. Two 3-dB quadrature couplers at two different frequencies, 0.9 and 10 GHz have been designed and simulated. The coupler designed at 900 MHz has been fabricated on Duroid substrate with microstrip technology. Compared to the standard quadrature coupler more than 65% area savings, has been achieved, and the first higher-order response appears at 5.8 GHz. The measured results show good agreement with theoretical prediction. (C) 2002 Wiley Periodicals, Inc.