| 摘要 |
An autodyne microwave motion-detection system includes a supervisory circuit for monitoring the operating status of the microwave energy-producing component of the system. According to a preferred embodiment, the supervisory circuit of the invention comprises a relatively low-cost, "general purpose UHF" diode, i.e. a multipurpose diode commonly used in circuits designed to accommodate UHF frequencies of up to only about 3 Gigahertz. The supervisory diode is positioned within, or in close proximity to, the resonant cavity of the microwave energy-producing element, the latter being designed to produce microwave energy at a substantially higher frequency (e.g., 10.5 Gigahertz). Due to its close proximity to the microwave energy-producing element (e.g. a Gunn diode) and its presence within the energy field produced thereby, the supervisory diode develops a small, but readily detectable, voltage whenever such element is radiating microwave energy. A voltage-sensing circuit is provided for sensing the instantaneous voltage across the supervisory diode, and the absence of a detectable voltage indicates that the microwave energy-producing element is not functional. Alternatively, the supervisory diode is replaced by an operational amplifier having a capacitor connected across its input leads, and the voltage induced on such input leads by the microwave field is detected to determine the operating status of the microwave transmitter.
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