Analysis and design of novel dual‐band branch line coupler with patterned ground plane

Abstract

AbstractThis article presents the novel dual‐band planar 90° branch line coupler with patterned ground plane, sometimes referred to as ‘defected ground structure.’ In the new layout, two cross coupling branches are added to the conventional branch line coupler. The additional branches make the design of dual‐band coupler at two arbitrary bands more flexible. Moreover, the used patterned ground plane makes an implementation of high impedance microstrip line easy and increases the electrical length of microstrip line. The basic principles of the novel coupler are analyzed and the design procedure is presented. For method validation, a dual‐band microstrip coupler operating at 2.1 GHz and 3.6 GHz was designed, tested, and analyzed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1000–1005, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24246