| 摘要 |
A VSWR meter and alarm device that produces an alarm when an undesirable VSWR is sensed on an RF transmission line. This device uses a single-arm directional coupler and detectors operating at least 15 dB into the "square law region" at full power. The single-arm directional coupler is capable of sensing the forward voltage wave and reflected voltage wave from a transmission line. The coupler isolates the forward and reflected voltages and each is converted into a direct current (dc) signal by a full-wave detector. Attenuator circuits are utilized between the coupler and detectors so that the detectors operate at least 15 dB into the "square-law region" at full power. The dc signals representing the forward and reflected voltages are then amplified and transformed into respective digital signals by a digital-to-analog converter. The digital signals are then transmitted to a microprocessor which operates an alarm system.
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