Abstract: A microwave point level instrument is adapted to detect level or change of products in a storage vessel. The instrument includes a microwave transducer periodically developing a pulse of microwave energy. A microwave bridge is driven by the transducer for receiving pulses of microwave energy. The bridge includes a reference arm receiving a portion of each pulse of microwave energy to be altered by a variable impedance tuning circuit. A measurement arm receives another portion of each pulse of microwave energy to be altered by dielectric properties of a product at a process seal installed in a storage vessel, in use. A detector arm develops a microwave signal responsive to imbalance in the bridge between the microwave energy altered by the tuning circuit and the microwave energy altered by the dielectric properties of the product. A sensing circuit is coupled to the bridge detector arm for developing an electrical signal responsive to the microwave signal representing the imbalance.