A microwave antenna probe incorporating a high-strength antenna coupler is described herein. The microwave antenna has a radiating portion connected by a coaxial feedline to a source of therapeutic energy, e.g., a microwave generator. Proximal and distal radiating portions of the antenna assembly are separated by a microwave antenna coupler. In embodiments, the described antenna coupler is generally cylindrical in shape and includes a central section having a diameter substantially equivalent to the radiating sections. The coupler includes end sections of a smaller diameter than the central section that are dimensioned to fit within the ends of the radiating section. The end portions include a groove that is adapted to receive a corresponding rib formed within the respective ends of the radiating section. The coupler includes an axial opening defined therein into which a tubular collar in fixed using an interference fit. The outward forces of the collar and the inward forces of the radiating section places the coupler under compression, which improves the strength of the coupler, and the strength of the overall probe assembly.