This paper derives microscopic behavior from the substrate field without invoking any quantum postulates. The substrate is assumed to possess a fundamental granularity scale l₀, which leads to discrete normal modes and thus to quantization of energy and momentum. Localized wave packets exhibit both wave‑like (interference, diffraction) and particle‑like (localization, discrete energy transfer) behavior—the substrate’s version of wave‑particle duality. Linear superposition of substrate excitations gives rise to quantum‑like superposition and, through the continuity of the wavefield, nonlocal correlations (entanglement). Intrinsic dissipation causes gradual loss of coherence between modes, providing a physical mechanism for decoherence and the appearance of measurement collapse. The second law of thermodynamics emerges from the same dissipative property. No separate axioms (collapse postulate, uncertainty principle as fundamental, etc.) are required; these are emergent consequences of the substrate’s discrete structure and dynamics. The paper outlines predictions, including modified dispersion at high energies and a derivation of an effective Schrödinger‑like equation from substrate parameters. The substrate field thus offers a realist, ontology‑based foundation for microscopic physics.Part IV of the Substrate Field Theory series