The principle of group delay swing enhancement in a transmission-line all-pass network using the combined coupling and dispersion boosting properties of a ferromagnetic substrate is proposed; full-wave verified and experimentally demonstrated using ferrite substrates as a proof of concept. The proposed group delay swing enhanced structures are compact in size, exhibiting a larger dispersion per unit area compared with other alternative techniques for dispersion enhancement, and a magnetically tunable group delay swing. The proposal to suppress the requirement of an external magnet is discussed based on self-biased ferromagnetic nanowire substrates and expected improvements are further pointed out. (C) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:589-593, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26658