Abstract: A fixture for determining the dielectric properties of a test material having a housing with an electrically shielded cavity defined therein to hold test material that surrounds an electrical conductor. Input and output circuits for coupling microwave energy into and out of the electrical conductor in the cavity are provided, each circuit having a transmission line having a center conductor extending through the housing with a tapping mechanism midstream of the conductor for coupling energy from the center conductor of the input circuit into the electrical conductor and from the electrical conductor to the center conductor of the output circuit. The tapping mechanisms are adjustable to vary the coupling of microwave energy with respect to the electrical conductor.

Abstract: A method for determining the dielectric properties of a test material using a housing with an electrically shielded cavity defined therein to hold test material that surround an electrical conductor. Input and output circuits for coupling microwave energy into and out of the electrical conductor in the cavity are provided, each circuit having a transmission line having a center conductor extending through the housing with a tapping mechanism midstream of the conductor for coupling energy from the center conductor of the input circuit into the electrical conductor and from the electrical conductor to the center conductor of the output circuit. The tapping mechanisms are adjustable to vary the coupling of microwave energy with respect to the electrical conductor.

Abstract: A lumped element microwave oscillator is mounted on the back plate secured to a wave guide for generating electromagnetic waves which propagate through the wave guide. The oscillator includes a two-terminal solid-state device, such as a Gunn diode, which exhibits negative resistance in the microwave range, connected in circuit with a dc source and lumped elements, including a variable capacitive element. The variable capacitive element is accessible without removing the back plate from the wave guide so that the capacitance can be easily adjusted for controlling the frequency of the oscillator. The power of the electromagnetic waves which propagate through the wave guide is preferably controlled by adjusting the coupling between the oscillator and the load in two ways. The physical orientation of various lumped elements mounted on the back plate can be adjusted with respect to the plane of the E field in the wave guide for controlling the coupling between the oscillator and the load in steps.

Abstract: A protective sleeve for protecting the handle of a percussion head tool such as a sledge hammer, axe or the like. A protective oversized rigid sleeve, e.g., of a metal, is positioned around the tool handle in a location adjacent to that head. The annular cavity defined between the oversized rigid sleeve and the handle is filled with a resilient energy absorbing material, e.g., with a rubber.

Abstract: A circuit for detecting line-to-ground and neutral-to-ground faults and in response thereto interrupting the line conductor. Included in the circuit is a magnetic core about which the neutral conductor and line conductor are wound to produce a zero net magnetomotive force in the core in the absence of a line fault and a non-zero net magnetomotive force in the presence of a line fault. A secondary winding wound on the core has at least one diode or thermistor connected thereacross. The diode or thermistor has a dynamic impedance, which is reflected back to the neutral winding, which decreases when current flows through the diode or temperature rises in the thermistor in response to an induced voltage in the secondary winding caused by non-zero net magnetomotive force in the core produced by a current imbalance in the line and neutral conductors due to a line fault.