Master of Science / Department of Electrical and Computer Engineering / Punit Prakash / Microwave ablation (MWA) is a minimally invasive thermal therapy predominantly used in the treatment of localized cancer. Previous studies have demonstrated clinical use of MWA for treating lung tumors, however, these procedures have relied upon the use of rigid percutaneous MWA applicators which can limit the range of accessible tumors and may have inherent disadvantages for use in lung tissue. The objective of this work was to develop and characterize a bronchoscopic MWA applicator suitable for use in a system that enables bronchoscopic transparencymal nodule access (BTPNA). A 3D coupled FEM electromagnetic-heat transfer model was implemented to optimize the antenna design and evaluate the expected ablation size and shape. A prototype device was fabricated and experimentally evaluated in ex vivo tissue to verify simulation results and demonstrate proof-of-concept. Simulated and experimental results indicate the proposed device could create ablation zones 19.3 – 31.0 mm in diameter with 30 – 45 W of power applied for 5 – 10 minutes. Future bronchoscopic MWA applicators based on the design proposed in this study could allow physicians an even less invasive treatment option for lung cancer with increased accuracy and efficacy and reduced risk of procedural complications immediately following a positive bronchoscopic lung biopsy.