An ablation system for directing energy to a target volume of tissue is provided. The ablation system comprises an ablation antenna probe including at least one radiating portion configured to output electromagnetic radiation and at least one electromagnetic shielding reflector configured for removable positioning on the antenna probe. The at least one electromagnetic shielding reflector is configured to block electromagnetic radiation from the at least one radiating portion through the at least one electromagnetic shielding reflector such that a particular directionality of the electromagnetic radiation from the at least one radiation portion to a target volume of tissue is achieved.