The Allied fuze used constructive and destructive interference to detect its target. The design had four or five tubes. One tube was an oscillator connected to an antenna; it functioned as both a transmitter and an autodyne detector (receiver). When the target was far away, little of the oscillator's transmitted energy would be reflected to the fuze. When a target was nearby, it would reflect a significant portion of the oscillator's signal. The amplitude of the reflected signal corresponded to the closeness of the target. This reflected signal would affect the oscillator's plate current, thereby enabling detection.