Abstract: A 180° hybrid coupler includes three coupled-line couplers connected between two inputs and two outputs. Each of the three coupled-line couplers is defined by at least one ground conductor and only two signal conductors.

Abstract: An oscillator has an oscillation portion that generates oscillatory electric signals due to a magnetization motion; and a first electric circuit that is connected in parallel to the oscillation portion. A current whose magnitude oscillates flows to the first electric circuit, and the first electric circuit is arranged such that a magnetic field generated by the current is applied to the oscillation portion.

Abstract: A radio transmitter has a quadrature modulating portion and an RF power amplifier. The RF power amplifier follows the quadrature modulating portion. A nonlinearity-caused distortion compensating system provided in the radio transmitter includes a power calculating portion for calculating a value related to a power of a transmission signal from first baseband signals quadrature with respect to each other. First distortion compensating coefficients are determined in response to the calculated power-related value. The first distortion compensating coefficients are designed to compensate for a signal distortion caused by a nonlinearity of the quadrature modulating portion. Second distortion compensating coefficients are determined in response to the calculated power-related value. The second distortion compensating coefficients are designed to compensate for a signal distortion caused by a nonlinearity of the RF power amplifier.

Abstract: The present invention provides a detector comprising a microstrip line having one end being grounded and another end connected to a main transmission line, a detection diode connected to the microstrip line, and a smoothing circuit for smoothing a signal detected by the detection diode.

Abstract: A thick film construct and quadrature coupler for use in fabricating devices such as IQ modulators, IQ demodulators, vector modulators, image reject mixers, and multi-channel mixers. The thick film construct includes a dielectric substrate base with a metallized backside, a first metal trace deposited on the non-metallized side of the substrate base, a dielectric layer deposited over and around the first metal trace, and a second metal trace deposited on the dielectric layer. The first and second metal traces are aligned over their widths and lengths so to form a balanced transmission line structure where the first and second metal traces represent top and bottom lines in the balanced structure. This thick film structure serves as the foundation for microwave capacitors, mixers, and other transmission line based structures, including a quadrature coupler.

Abstract: A printed circuit board includes an oscillator and a modulator. The oscillator includes a first printed inductor and a capacitive diode which are printed on one side of the printed circuit board. The modulator includes a second printed inductor coupled to the first printed inductor and printed on the same side of the printed circuit board as the oscillator. A conductive surface at a reference potential is arranged the other side of the printed circuit board and in the vicinity of the oscillator and the modulator and electrically coupled to the oscillator and the modulator using conductive through holes.

Abstract: The invention relates to an electronic life detection system, in particular for the searching for buried persons and the surveillance of buildings, having a microwave transmitting/receiving device for generating and radiating microwaves into an area to be investigated and for registering the microwave signal reflected from the area under surveillance and modulated with the frequencies corresponding to the life functions of any living beings present in the area, which device has a first signal-conditioning device, and a second signal-conditioning device.

Abstract: An improved modulator circuit for mixing a modulation signal with a carrier signal includes first and second harmonic mixers which are operative to produce modulated output signals at an output frequency corresponding to both the sum and the difference of the modulation signal frequency and the even harmonic frequencies of the carrier signal frequency. In one configuration employing a 90.degree. hybrid, the output signals of the harmonic mixers are combined to produce a single sideband modulated output signal. A novel harmonic mixer circuit is also provided along with demodulator circuits and methods of modulating and demodulating modulation signals.

Abstract: A method and apparatus for modulating or demodulating a radio frequency (RF) signal which incorporates a pair of quadrature couplers. In demodulating an RF signal, an LO signal and the RF signal are each phase shifted -90 degrees by the couplers. The RF and LO signals are mixed as are the phase-shifted RF and LO signals. Each mixed signal is low-pass filtered and the filtered signals are added thereby producing an intermediate frequency signal.

Abstract: Logarithmic amplifiers which have a logarithmic transfer characteristic may be used in microwave instrumentation. Such an amplifier includes a series of MESFET distributed amplifiers (DA1-DA8) connected in cascade, with each of the MESFET distributed amplifiers (DA1-DA8) having a gate transmission line (G1-G8) and a drain transmission line (D1-D8) which share a common ground or source line (5), and a number of MESFETs (1-4) connected in parallel with their gate electrodes (g) connected at spaced intervals along the gate transmission line (G1-G8) their drain electrodes (d) connected at spaced intervals along the drain transmission line (D1-D8) and their source electrodes (s) connected to the source line (5). A low pass filter (LPF1-LPF8) is connected to the downstream end of the gate transmission line (G1-G8) of each distributed amplifier (DA1-DA8) with each low pass filter (LPF1-LPF8) passing only the rectified component of the travelling wave passing along each gate transmission line (G1-G 8).