AbstractA new representation of the coupling coefficient of resonators has been obtained by the authors using the coupled mode theory. In this expression, the coupling coefficient is given by an overlap integral of the electric field and the magnetic field. This expression is extremely useful for explanation of the physical meaning of coupling. In the present paper, various microstrip resonators are discussed and their coupling mechanisms are explained by the above theory resulting in a clear interpretation that includes phenomena hitherto not adequately explained. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(9): 11– 18, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20342