The present article introduces a comprehensive theoretical framework titled Inverse-Phase Cosmic Duality (IPCD), derived from systematic analysis of the recently conceptualized Aj Signal Structure (AJSS). This model proposes a new representation of multidimensional cosmic field interactions governed by inverse-phase symmetry at micro-quantum, subatomic, and macrocosmological scales. Using analytical expansion, numerical modeling, and conceptual simulations, this study demonstrates that the Aj field oscillatory pattern maintains recursive selfsimilarity, allowing the formation of energy–geometry correspondences observable across particle dynamics, gravitational lensing, and multi-layer field propagation. The mathematical core of the theory is based on a three-dimensional parametric field equation in which each phase-inverted component inversely correlates with the curvature density of the surrounding spacetime sublayer. The results of this model imply a potential unification point between the electromagnetic tensor and curvature tensors through the Aj-Phase Transformation Function (AjPTF). Furthermore, the IPCD framework provides predictions regarding energy dispersion, inverted-phase radiation signatures, and anisotropic spatial folds, forming a basis for future quantum-gravimetric experiments. Keywords: Aj Signal Structure, Inverse-Phase Cosmic Duality, multidimensional fields, quantum curvature, phase inversion, unified cosmology, geometric energy mapping.