Microwave antenna assemblies incorporating a resilient insulating coupler are described herein. The microwave antenna includes a radiating portion connected by a coaxial feedline to a power generating source, e.g., a generator. Distal and proximal radiating portions of the antenna, which correspond to inner and outer conductors provided by the coaxial feedline, are separated by the resilient insulating coupler. The described coupler includes a proximal threaded portion, and an overmolded insulating portion formed from an elastomeric material. The inner conductor of the coaxial feedline is joined to the threaded portion of the coupler, and is placed under tension to draw together the distal radiating portion, the coupler, and the proximal radiating portion into a single rigid assembly. In use, the resilient coupler provides increased strength and reliability by absorbing mechanical stresses typically encountered during microwave ablation procedures.