Abstract: A radome for enclosing a microwave antenna, including a structurally rigid and electrically thin enclosure wall having a foam shell and foam ridges projecting inwardly from the foam shell, so that the foam ridges and the void regions between them form a ridged wall layer.

Abstract: A seawater probe for measuring a physical parameter which includes a sensor element having an electrical characteristic dependent on the parameter and a detector circuit for deriving a measurement signal corresponding to a measured value of the electrical characteristic, the improvement including a reference element having a known, stable value of the electrical characteristic connected in series with the sensor element, the reference and sensor elements being powered by a single power supply, means for selectively connecting the sensor and reference elements separately in the detector circuit, and means for calibrating the detector circuit using the known value of the electrical characteristic of the reference element and the measurement signal derived when the reference element is in the detector circuit.

Abstract: A sonobuoy having a terminal weight and sensor for deployment beneath the surface of the water after the buoy has been launched from an aircraft and impacted the water. A circuit assembly and antenna for processing output from the sensor and for transmitting a signal is provided. A cable for connecting the sensor and circuit assembly is also included. A housing for the sonobuoy is a blow molded seamless thermoplastic shell which surrounds the circuit assembly.