Abstract: A device is described using at least one polyconductor film as an active ment lens of an electrical circuit for detecting incident laser radiation. In several alternative embodiments, a polyconductor film is located at the focal point of at least one lens which focuses the incident laser radiation on the film. The polyconducting film acts as a variable resistor of a balanced bridge network and upon receipt of radiation causes an imbalance in the bridge for radiation detection. The film changes phase with increasing incident power such that it protects itself against high levels of radiation. The lenses can also be polyconducting films and another film shielded from the radiation may be included to compensate for temperature fluctuations and maintain circuit sensitivity.

Abstract: An H-plane sectoral horn antenna is loaded with low-loss dielectric inserts n alternative embodiments so as to reduce beamwidth, increase axial gain and to achieve non-mechanical beam scanning. In one embodiment, the antenna is transversely loaded with a multi-layer dielectric array containing an air gap of critical thickness between four dielectric strips. In another embodiment, the antenna is longitudinally and symmetrically loaded with wedge-shaped dielectric strips separated by a critical air gap between the dielectric and antenna walls.

Abstract: A method and apparatus for continuous and contactless grading and counting in which the articles or products to be surveyed are passed beneath a microwave radiometer antenna on a conveyor belt or the like, so as to measure the frequency spectrum of the radiation temperature emitted by the articles at a convenient temperature and relating the "signature" thus obtained to a non-electrical parameter such as weight or size.

Abstract: Apparatus for detecting the presence of an underwater object measures variations in the input impedance of a monopole antenna to provide data on the object. A sweep generator supplies a first electrical signal of varying frequency for transmission as an electromagnetic signal propagated through water from the antenna, and means are provided for detecting reflections of the electromagnetic signal to provide a second electrical signal, which is compared with the first electrical signal to provide an output signal. Preferably, the monopole antenna is one of three such antennas, which are provided with means for comparing input impedances of the antennas to provide an output signal representing the bearing of the object.

Abstract: A method and device for absorbing microwave energy avoid the expense and bulk of prior art arrangements, and provide greater efficiency, by forming a flame in the path of the microwave and supplying a seeding substance into the flame to produce a plasma flame column which absorbs the microwave. The seeding substance is preferably an alkali salt solution, e.g. KNO.sub.3.

Abstract: An attractant such as an ultra-violet light is reflected from the trap and insects are thereby attracted and fly through a surrounding mesh to inside the trap. They are then stimulated by a high frequency electro-static field generated by an electronic unit within the trap, to fly towards an electrocuting grid. When an insect enters the grid, a high voltage short duration arc is struck which rapidly heats and dehydrates the insect thus killing same. This can be accomplished either with or without actual contact of the insect across the grid. The arc dissipates a fixed charge generated by the unit so that continuous arcing does not occur. Because of the dehydration effect, the insects drop from the grid and do not stick thereto. The electronic circuit is designed so that if a relatively large insect enters the grid, and the dehydration is not completed by the arc, dielectric heating will occur as a result of the moisture remaining thus completing the dehydration process.