Abstract: A printed circuit board includes vibration areas where vibration sensitive components of an electrical circuit design fabricated on the printed circuit board are mechanically isolated from supporting circuitry. The present invention provides a printed circuit board with areas having an increased natural resonant frequency of vibration for the circuit board area where the vibration sensitive circuit is located. The printed circuit board comprises a number of slots, holes or other openings around the vibration sensitive circuitry. In addition, one or more circuit board conductive paths are provided for maintaining electrical conductivity between the isolated circuit and the supporting circuits.

Abstract: A method and apparatus determines the location of a signal transmitter located at an unknown location by using externally-induced intermodulation distortion emitted from the signal transmitter. A transmitter locator emits an interrogation signal having a frequency that is offset from the frequency of the signal emanating from the signal transmitter. The interrogation signal and the carrier signal of the signal transmitter are "mixed" within the signal transmitter to form an intermodulation product signal. The intermodulation product signal having a different frequency is then radiated from the unknown signal transmitter. A receiver tuned to the frequency of the intermodulation signal detects the returned signal and a processor determines the range and direction from the transmitter locator to the location of the signal transmitter.

Abstract: A directional coupler having a broadband frequency response comprises a pair of parallel TEM transmission lines having an input port, a thru port, a coupled port, and an isolation port. A quarter-wave, short circuited transmission line coupled to the thru port, and a half-wave, open circuited transmission line coupled to the isolation port functions to flatten the frequency response between the input port and the thru port and between the input port and the coupled port and to increase the operating bandwidth of the directional coupler.

Abstract: A printed circuit board includes vibration areas where vibration sensitive components of an electrical circuit design fabricated on the printed circuit board are mechanically isolated from supporting circuitry. The present invention provides a printed circuit board with areas having an increased natural resonant frequency of vibration for the circuit board area where the vibration sensitive circuit is located. The printed circuit board comprises a number of slots, holes or other openings around the vibration sensitive circuitry. In addition, one or more circuit board conductive paths are provided for maintaining electrical conductivity between the isolated circuit and the supporting circuits.

Abstract: A high power RF resistor for use, for example, as an isolation resistor in an RF hybrid splitter/combiner is formed on a thermally conductive substrate. A first insulating beryllia (BeO) layer extends over the substrate and has a top surface and a bottom surface. A first metallization layer extends over the top surface of the first insulating layer and includes a longitudinally-extending gap. A second insulating BeO layer is positioned above the first insulating layer and includes a top surface, a bottom surface and first and second side surfaces. A second metallization layer surrounds the bottom surface and the first and second side surfaces of the second insulating layer and has a longitudinally-extending gap, the gap in the second metallization layer positioned to be in alignment with the gap in the first metallization layer. This structure forms a Faraday shield between the resistive layer and ground to thereby reduce the I.sup.

Abstract: A wide range reflective phase shifter/modulator including a 3dB hybrid splitter having ports A, B, C and D. An input signal to be phase modulated is applied to port-A and the phase modulator output signal is derived from port-C. Ports B and D are terminated with reactive circuits, which must be identical, including four variable reactive elements such as varactor diodes, the capacitance of which can be controlled by a modulating control voltage. By controlling the capacitance of the varactor diodes, the amount of phase shift in the signal derived from port-C is controlled. An alternative embodiment includes a circulator having ports E, F and G. An input signal to be phase modulated is applied to port-E and the phase modulator output signal is derived from port-G. Port-F is terminated with a reactive circuit, which includes two variable reactive elements such as varactor diodes, the capacitance of which can be controlled by a modulating control voltage.

Abstract: Low power for a radio transmitter is indicated by an output power detector voltage falling below a low power reference voltage derived from an existing power control circuit.

Abstract: Two printed circuit boards are connected together by a female coaxial connector, open at both ends, on one board, and by an elongated pin on the other board. When the boards are fastened together, the pin engages the female coaxial connector from one end. When the boards are separated, a male coaxial connector may engage the female coaxial connector from the other end.

Abstract: A radio transceiver has a single reference oscillator and a receiving frequency synthesizer and a transmitting frequency synthesizer. The synthesizer frequencies are selected so that the receiving intermediate frequency and a transmitting intermediate frequency (produced by the transmitted frequency mixing with the received frequency) are spaced widely apart. Thus, any beat note between the two intermediate frequencies is outside the passband or filter bandwidth in the receiver circuit.