A microwave field-detecting needle assembly (110), comprising:a distal portion (130) configured for insertion into tissue；a proximal portion (160)；a junction member (50) disposed between the distal portion and the proximal portion, the junction member including a recess (56) defined therein； anda rectifier element (58) disposed in the recess and including a first terminal (59a) electrically coupled to the distal portion and a second terminal (59b) electrically coupled to the proximal portion.
