Northrop Grumman Systems Corporation

Trw Limited

The Aerospace Corporation

Nonlinear Technologies Ltd.

Stephen A Maas

Mark Kintis

Daniel K Ko

Flavia S Fong

A nonlinear transmission-line waveform generator for generating a comb of frequencies and relatively short duration pulses, for example, in the range of picoseconds and tens of picoseconds, that are adapted to being utilized with ultra wideband radios in order to improve the bandwidth of such radios by an order of magnitude, for example, up to tens and even hundreds of GHz. In particular, the nonlinear transmission line waveform generator in accordance with the present invention consists of a microstrip or coplanar waveguide line. In accordance with an important aspect of the invention, the &Dgr;C/&Dgr;V characteristic of the nonlinear transmission line is matched to the frequency and amplitude of the input sinusoidal waveform. By matching the &Dgr;C/&Dgr;V characteristics of the nonlinear transmission line to the input sinusoidal waveform, the output of the nonlinear transmission line produces a comb of frequencies that are multiples of the input sinusoidal waveform frequency, making it suitable as a harmonic generator. The nonlinear transmission line can also be used to generate relatively short duration pulses by disposing a shorting stub at the output. The shorting stub causes the waveform to be reflected 180&deg; out of phase so that it cancels the trailing edge of the original output from the nonlinear transmission lines to form a short duration pulse in the picosecond range. The length of the stub determines the width of the resultant output pulse.

Nonlinear transmission line waveform generator having an input voltage matched to the C/V characteristic of the transmission line

A programmable phase shifter (,) includes a variable delay line formed from a nonlinear transmission line (NLTL) (,), which enables the device to be used in applications where the frequency of the input signal varies. A variable DC bias applied to the NLTL (,) varies the NLTL's phase velocity and delay. Since the characteristic impedance of a transmission line changes as a function of the DC bias, the input voltage standing wave ratio (VSWR) also changes. In order to compensate for the change in the input VSWR, a pair of NLTLs (,) are coupled at the input and output to a pair of hybrid couplers (,). In an alternate embodiment of the invention, the hybrid couplers (,) are replaced with 180&deg; power splitters (,) in order to reduce distortion of the device. In other embodiments of the invention (,), a nonlinear transmission lines are used to form both discretely variable and continuously variable digital phase shifters (,).

Wideband low-loss variable delay line and phase shifter

An FM-CW radar transceiver comprising an oscillator connected to an input of a power divider having first and second terminal outputs. The first terminal output of the power divider is connected to an input of a first diode and a first shorted stub. The second terminal output of the power divider is connected to an input of a phase shifter with the output of the phase shifter connected to an input of a second diode and a second shorted stub. The outputs of the first and second diodes are each connected to inputs of first and second intermediate frequency (IF) filters and then through first and second IF blocking structures terminating at a common antenna port. An open stub is connected to the common antenna port with the outputs of the first and second IF filters each connected to an IF port or channel. In use, the FM-CW transceiver operates as a frequency multiplier for transmitting, and simultaneously as a subharmonically pumped 'I/Q' mixer for reception.

FM-CW radar transceiver

A simple balanced-mixer circuit that uses the resistive channel of a GaAs MESFET exhibits superior intermodulation performance, with other performance parameters, e.g., conversion loss, port impedances, and LO sensitivity, being equal to or better than other diode mixers.

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Long Beach, CA, United States of America

Stephen A Maas