Microwave spectrometer apparatus

Claim 2

In a microwave spectrometer apparatus, circulator means having first, second, third and fourth ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, variable phase shifter means having a first and second state coupled to said third port of said circulator for receiving the cavity microwave signal and reflecting such signal with a first and second phase relative to a reference phase derived from said energy source, microwave detector means having an output signal, said detector being coupled to said fourth port of said circulator means for receiving the microwave cavity signal with a phase relation which is a function of the phase shift produced by said phase shifter means, means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide said reference phase for said detector, and means for causing said microwave detector signal output to selectively change from a pure absorption mode signal to a pure dispersion mode signal, said means comprising means to cyclically switch said variable phase shifter between said first and second state.

Claim 3

In a microwave spectrometer apparatus, circulator means having first, second, third and fourth ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, variable phase shifter means having a first and second state coupled to said third port of said circulator for receiving the cavity microwave signal and reflecting such signal with a first and second phase relative to a reference phase derived from said energy source, microwave detector means having an output signal, said detector being coupled to said fourth port of said circulator means for receiving the microwave cavity signal with a phase relation which is a function of the phase shift produced by said phase shifter means, means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide said reference phase for said detector, and means for causing said microwave detector signal output to selectively change from a pure absorption mode signal to a pure dispersion mode signal, said means comprising means to cyclically switch said variable phase shifter between said first and second state.

Claim 4

In a microwave spectrometer apparatus, circulator means having first, second, third and fourth ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, variable phase shifter means having a first and second state coupled to said third port of said circulator for receiving the cavity microwave signal and reflecting such signal with a first and second phase relative to a reference phase derived from said energy source, microwave detector means having an output signal, said detector being coupled to said fourth port of said circulator means for receiving the microwave cavity signal with a phase relation which is a function of the phase shift produced by said phase shifter means, means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide said reference phase for said detector, and means for causing said microwave detector signal output to selectively change from a pure absorption mode signal to a pure dispersion mode signal, said means comprising means to cyclically switch said variable phase shifter between said first and second state.

Claim 5

The apparatus of claim 1 including an audio oscillator wherein said means to switch said variable phase shifter is responsive to said audio oscillator for controlling the sequence of switching between said first and second state.

Claim 6

The apparatus of claim 2, including means for coupling said detector output signal to an AFC circuit for tuning the frequency of said microwave energy source when said signal represents an absorption mode signal and for coupling said detector output signal to a receiver when said signal represents a dispersion mode signal, said means for coupling being responsive to said audio oscillator.

Claim 7

The apparatus of claim 3, including, means for producing a polarizing magnetic field in said cavity resonator, means for modulating the polarizing magnetic field in the cavity at a high field-modulation frequency, said high modulation frequency being provided said receiver to enable synchronoUs detection of said dispersion signal.

Claim 8

Apparatus of claim 3 wherein said variable phase shifter comprises a first and second spaced apart electrical discharge means spaced from a reflective wall structure, and wherein said means to switch said variable phase shifter is responsive to a first and second related pulse sequence connected respectively to said first and second electrical discharge means.

Claim 9

Apparatus of claim 2 wherein said means to switch said variable phase shifter comprises means for switching between said first and second state at least twice during each cycle of said audio oscillator.

Claim 10

Apparatus of claim 5, including field modulation windings coupled to said audio oscillator wherein said first related pulse sequence is a low multiple of the frequency of the audio oscillator driving the field modulation windings and said second related pulse sequence is a high frequency pulse train which occurs between pulses of said first related pulse sequence.

Claim 11

The apparatus of claim 3 including, means for modulating the frequency of the microwave energy supplied to said circulator means and thence to said cavity resonator from said microwave energy source means to produce modulation of the microwave cavity signal reflected to said detector means at a second modulation frequency which is a function of the frequency of the frequency modulation, means for detecting the second modulation component in the microwave cavity signal during said period that said detector signal represents the absorption mode signal, means responsive to the detected second modulation component for determining and storing a frequency correction signal, and means for tuning the frequency of said microwave energy source to the resonant frequency of said microwave cavity means responsive to said stored correction signal.

Claim 12

The apparatus of claim 3 wherein said means for coupling includes a gate responsive to said audio oscillator for gating the cavity output signal of said detector means such that the cavity signal components of one phase are gated to one receiver and components of a second phase are gated to a second receiver.

Claim 13

The apparatus of claim 5 wherein said first and second electrical discharge means are spaced from said wave reflective wall along the path of the microwave cavity signal by an odd number of 1/4 and 1/8 wavelengths, respectively, for modulating the phase of the microwave cavity signal at the first and second phase modulation frequencies by 180* and 90*, respectively.

Claim 14

The apparatus of claim 1 including, means for variably controlling the coupling of wave energy between said circulator means and said cavity resonator means, means for modulating the phase shift produced by said phase shifter means at a modulation frequency to produce a modulation signal component in the detected cavity signal at a frequency which is a function of the phase modulation frequency, means for phase detecting the modulation signal to derive a control output, means for feeding the control output to said cavity coupling control means for causing said control means to automatically impedance match said cavity to said circulator means.

Claim 15

The apparatus of claim 1 including automatic frequency control means for tuning the frequency of said microwave energy source to the resonant frequency of said microwave cavity means, and means for synchronizing operation of said automatic frequency control means to the absorption mode portions of said microwave detector output.

Claim 16

In a microwave spectrometer apparatus, circulator means having first, second, third and fourth ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, variable phase shiftEr means coupled to said third port of said circulator for receiving the cavity microwave signal and reflecting such signal with a certain phase relation to said circulator means, microwave detector means coupled to said fourth port of said circulator means for receiving the microwave cavity signal with a phase relation which is a function of the phase shift produced by said phase shifter means, and means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide a reference phase for said detector, wherein said phase shifting means comprises a wave reflective wall structure and an electrical discharge means responsive to the modulation signal and spaced from said reflective wall structure, said electrical discharge means serving to reflect the microwave cavity signal back to said circulator means when said electrical discharge means is rendered wave reflective in response to the modulation signal, and said wall serving to reflect the microwave cavity signal when said electrical discharge means is rendered wave transmissive.

Claim 17

In a microwave spectrometer apparatus, circulator means having first, second, third and fourth ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, variable phase shiftEr means coupled to said third port of said circulator for receiving the cavity microwave signal and reflecting such signal with a certain phase relation to said circulator means, microwave detector means coupled to said fourth port of said circulator means for receiving the microwave cavity signal with a phase relation which is a function of the phase shift produced by said phase shifter means, and means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide a reference phase for said detector, wherein said phase shifting means comprises a wave reflective wall structure and an electrical discharge means responsive to the modulation signal and spaced from said reflective wall structure, said electrical discharge means serving to reflect the microwave cavity signal back to said circulator means when said electrical discharge means is rendered wave reflective in response to the modulation signal, and said wall serving to reflect the microwave cavity signal when said electrical discharge means is rendered wave transmissive.

Claim 18

The apparatus of claim 13 wherein said electrical discharge means includes a diode.

Claim 19

The apparatus of claim 13 wherein the spacing from said electrical discharge means to said wave reflective wall structure is an odd integral number of one eighth wavelengths at the resonant frequency of said cavity resonator, whereby a 90* phase modulation of the microwave cavity signal is obtained at the phase modulation frequency.

Claim 20

In a microwave spectrometer apparatus, circulator means having first, second, and third ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, microwave detector means, variable phase shifter means coupled to said third port of said circulator for receiving the cavity microwave signal and transmitting said signal with a certain phase relation to said microwave detector means, means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide a reference phase for said detector, automatic frequency control means for tuning the frequency of said microwave energy source to the resonant frequency of said microwave cavity means, means for cyclically modulating the phase of said variable phase shifter, and means for synchronizing operation of said automatic frequency control means with the phase modulation cycle, said means for synchronizing including means for rendering said automatic frequency control means responsive only during certain portions of the cycle of said modulation of said variable phase shift.

Claim 21

In a microwave spectrometer apparatus, circulator means having first, second, and third ports, microwave energy source means coupled to said first port of said circulator for supplying microwave energy to said circulator means, cavity resonator means for containing a sample to be investigated and coupled to said second port of said circulator for applying microwave energy to the sample and for reflecting a cavity microwave signal to said circulator, microwave detector means, variable phase shifter means coupled to said third port of said circulator for receiving the cavity microwave signal and transmitting said signal with a certain phase relation to said microwave detector means, means independent of said circulator for coupling said microwave energy source to said microwave detector means for applying microwave energy from said source to said detector means to provide a reference phase for said detector, automatic frequency control means for tuning the frequency of said microwave energy source to the resonant frequency of said microwave cavity means, means for cyclically modulating the phase of said variable phase shifter, and means for synchronizing operation of said automatic frequency control means with the phase modulation cycle, said means for synchronizing including means for rendering said automatic frequency control means responsive only during certain portions of the cycle of said modulation of said variable phase shift.

Claim 22

The apparatus of claim 16 wherein said means for synchronizing said automatic frequency control means with the phase modulation cycle includes a gate for gating the detected cavity signal of one phase to said automatic frequency control means, and means for applying a cyclical gating signal to said gate in synchronism with the phase modulation cycle of the cavity signal.

Claim 23

The apparatus of claim 16 including, means for producing a polarizing magnetic field in said cavity resonator, means for modulating the polarizing magnetic field in the cavity at a field modulation frequency responsive to an oscillator, and wherein said phase modulation frequency is also responsive to said oscillator such that the phase modulation of the cavity signal is synchronized with the field modulation frequency.