Virtual‐Source‐Assisted Time‐Reversal Phase Control for Efficient Microwave Heating in a Six‐Port Cylindrical Cavity

ABSTRACT

Time‐reversal (TR) microwave heating offers the ability to focus electromagnetic energy onto a desired region, but its practical implementation is limited by the need for accurate absolute phase measurements. To overcome this barrier, this letter presents a virtual‐source‐assisted TR method implemented in a six‐port cavity. By introducing an internal virtual radiation source in the forward process, the backward excitation power ratios and inter‐port relative phase differences are directly extracted, eliminating the need for absolute source‐to‐port TR phase acquisition while retaining compensation for fixed channel‐dependent hardware phase offsets. Coupled electromagnetic‐thermal simulations and physical heating experiments validate the predicted TR temperature response, while numerical comparisons under the same total input power show that the TR scheme yields higher temperature rises than the investigated equal‐power, fixed‐phase‐difference, and random excitations. Crucially, over an extended dielectric spectrum (real part: 5–75, loss tangent: 0.1–0.9), numerical evaluations demonstrate that the TR scheme consistently outpaces the strongest non‐TR alternative at each dielectric‐property combination by a factor of 1.4 to 3.1. Furthermore, the efficient heating performance remains robust against the moderate temperature‐induced dielectric drift investigated in this study, and periodic dielectric updating and TR‐parameter recalculation can be used to maintain efficient heating when larger dielectric changes occur. The proposed method provides a practical and robust approach for TR‐based efficient microwave heating in multiport cavities.