Her Majesty the Queen in Right of Canada, As Represented by the Minister

Her Majesty the Queen in Right of Canada (...)

Minister of National Defence

Canadian Department of National Defence

William D Cornish

Larry J Conway

Trevor W Tucker

Paul I Pulsifer

Lawrence Bruce Hewitt

Francois A Gauthier

A microwave signal receiving apparatus comprises a delay line for distributing a microwave signal, samplers for sampling the signal spatially along the delay line and producing analog samples, analog-to-digital converters for converting the analog samples to digital samples, and digital memories associated with each converter for storing the digital samples.

Wide band, complex microwave waveform receiver and analyzer, using

An RF signal receiving/transmitting apparatus for use with a phased array antenna having a plurality of antenna elements comprises a plurality of signal processing circuits, each circuit being connected to and associated with one of the antenna elements and including a signal distributing/combining device connected to its associated element, a plurality of sampling gates for spatially sampling a distributed signal or applying analog samples to the distributing/combining device, and analog-to-digital or digital-to-analog converters connected to an analyzer for analyzing/generating a plurality of digital samples which are received or to be transmitted by the antenna elements.

Phased array antenna feed

A method and apparatus for generating complex microwave signals in which microwave signals are directly generated by the simultaneous application of a number of analog voltages to points distributed along a transmission line. These signals may be generated by a digital computer or other means and may be altered in phase, frequency and amplitude by simply varying the relative levels of the analog voltages applied along the transmission line, thus allowing very complex microwave waveforms to be generated.

Complex microwave signal generator

A broadband non-resonant microwave frequency halver which simultaneously decouples the input frequency from the output port through phase cancellation and couples the subharmonic frequency to the output port through phase addition providing good isolation between input and output over a very broad frequency range. The implementation of this circuit specifically excludes resonant, or frequency dependent elements and therefore has a much broader band of operation than previous circuits which relied on resonant phenomena.

Non-resonant microwave frequency halver

A microwave frequency divider operable in 2-16 GHZ range over octave bandwidths. A circuit resonant at a subharmonic frequency is formed by a pair of input microstrip transmission lines coupled to a pair of output microstrip transmission lines. Each input line is terminated by a varactor diode. The input signal is supplied to the resonant circuit by a pair of microstrip lines functioning as a two stage quarter wave transformer. A pair of slots are formed in the ground plane underneath the resonant circuit. The electric field distortion thereby produced serves to bias the varactors into forward conduction for efficient subharmonic generation.

Self-biasing broadband frequency divider

A microwave frequency divider operable in 8-16 GHZ range. A circuit resonant at a subharmonic frequency is formed by a pair of input microstrip transmission lines coupled to a pair of output microstrip transmission lines. Each input line is terminated by a varactor diode. The input signal is supplied to the resonant circuit by a pair of microstrip lines functioning as a two stage quarter wave transformer. A metal plate positioned over the resonant circuit and closely spaced from it functions to extend the upper end of the frequency range. A bias supply line for the diodes has a portion passing through a resistive foam block to remove spurious signals. A movable stub is positioned along the bias supply line to extend the lower end of the frequency range.

Broadband frequency divider

Disclosed is a microwave frequency generator for producing a microwave signal with high frequency accuracy, high spectral purity, low noise and high frequency stability. It is known to phase lock the fundamental microwave oscillator to a highly stable crystal oscillator at lower frequency and convert to a higher output frequency with a multiplier or harmonic generator but fm noise is also multiplied. The present invention avoids this problem by using MESFET frequency dividers to phase lock a microwave oscillator to a stable reference oscillator without the need for frequency multipliers. The MESFET frequency divider provides signal gain instead of loss during operation.

Microwave phase locked loops using FET frequency dividers

A frequency divider is known which uses varactor diodes in a circuit which resonates at f.sub.o /N where N is an even integer. Because of circuit losses within the varactor diodes, amplifiers are generally required to recover the input signal level. For systems that require cascaded frequency dividers at least one amplifier is required for each frequency divider. The present invention overcomes these problems by providing a microwave frequency divider to perform parametric frequency division and amplification simultaneously at microwave frequencies. A signal f.sub.o is applied to an input transmission line which forms, with the inherent frequency dependent non-linear gate-to-source capacitance of at least one MESFET, a circuit resonant at f.sub.o /N, wherein N is an even integer such as 2. The source-drain path of the MESFET is coupled via an output transmission line to a balun transformer having an output to provide amplified signals at f.sub.o /N. The transmission lines may be microstrip, stripline or other suitable type of transmission line.

Wideband MESFET microwave frequency divider

It is known to generate mircowave frequencies by locking the fundamental output frequency of a microwave oscillator to a multiple or sub-multiple of the output frequency of a highly stable crystal oscillator operating at a lower frequency than the microwave oscillator. Phase-locked loops are used together with frequency multipliers or dividers. One problem is that the frequency lock range decreases as successively higher and weaker harmonics are used for locking. This limits the practical harmonic locking range to multiples of approximately less than ten. The present invention eliminates this problem and allows microwave signals which have a frequency greater than 10 times the reference frequency to be phase locked without an impractical reduction of the capture range. As well, in conventional phase locked loop systems which use multipliers, fm modulation which is intentionally injected must have a modulation index less than 1.0. The present invention eliminates this problem and increases the allowed modulation index by a factor N, where N is the division ratio of the frequency divider used in the feedback loop. The present invention uses a microwave parametric frequency divider to phase lock a microwave oscillator to a stable reference oscillator without the need for frequency multipliers. The output f1 of an rf oscillator is divided by N and fed to one input of a phase detector. The phase detector has another input fed by a reference oscillator of predetermined frequency f.sub.2. The phase detector has an output fed to a control input of the rf oscillator which causes the rf oscillator to produce a frequency of Nf.sub.2 which is directly fed to the rf output of the apparatus. Note that no multiplier is required.

Microwave frequency division by phase locked loops

Frequency division of microwave signals may be done using heterodyne conversion but there are limits to the ultimate instantaneous bandwidth that can be down-converted using this method and any frequency aberrations of the local oscillator show up at the output. It is also known to down-convert microwave signals by using a varactor divide-by-two system. However, to divide by factors greater than two, these dividers must be cascaded which results in losses that must be compensated by amplifiers. The present invention alleviates the foregoing problems by providing a single-stage analog microwave frequency divider which will divide microwave signals by four. The divider comprises a substrate having an input microstrip transmission line capacitively coupled to a resonator formed of first and second spaced apart parallel microstrip transmission lines of predetermined length. One end of each of these lines are joined together by a transverse microstrip transmission line and the other end of each of these lines is connected to substrate ground via an associated varactor diode. The first and second microstrip transmission lines are electromagnetically coupled to third and fourth microstrip transmission lines and the third and fourth microstrip transmission lines are connected in series to a stripline balun comprising an output of the divider.

Growing community of inventors

Nepean, Canada

William D Cornish