This video presents a comparative analysis of microwave ablation applicators, including both antenna-based and open waveguide designs, which are guided and inserted into tumors via catheters. Applicators previously proposed in the literature are evaluated through both electromagnetic and thermal simulations. The objective is to assess temperature distribution within the tumor and surrounding healthy tissues; with a focus on identifying patterns of heat diffusion. Although a variety of applicators have been designed, each typically operates at different central frequency or targets specific tumor shapes and tissue types. In this video, researchers standardize conditions by analyzing multiple applicators’ designs for the same tumor type. The results highlight the shape of the ablation zone and corresponding temperature distribution, offering insights into potential healthy tissue damage. This comparative analysis provides critical information for optimizing microwave ablation applicators for more precise and effective treatment.