Analysis of Variable-Depth Sample Using a Sweeping Microwave Signal

Abstract

The present invention relates to an apparatus and method for analysing an amount of at least one component in a sample by measuring a microwave signal that has passed at least partially through the sample. The apparatus preferably comprises: a microwave generator that generates a continuous linear sweeping microwave signal varying in frequency, a microwave transmitter, a microwave receiver, at least one microwave analyser that analyses phase shift and/or change in amplitude of a transmitted and received signal, a means for determining a depth of the sample and a processor that determines the amount of the component(s) in the sample from the determined depth and an output signal from the microwave analyser.

1 . A sample analysis apparatus that measures an amount of at least one component in a sample comprising: 
 (i) a microwave generator that generates a continuous linearly sweeping microwave signal varying in frequency;    (ii) a microwave transmitter that transmits the generated signal;    (iii) a microwave receiver that receives the transmitted signal;    (iv) at least one microwave analyser that generates an output signal, which is operatively connected to the microwave transmitter and to the microwave receiver; said output signal indicating a phase shift and/or an attenuation of amplitude of the microwave signal when comparing the generated signal and the received signal, and the at least one microwave analyser is capable of measuring the phase shift and/or attenuation of the amplitude of the microwave signal by random stratified sampling of the received signal;    (v) means for determining a depth of the sample located between said microwave transmitter and said microwave receiver; and    (vi) a processor that determines the amount of said at least one component in said sample from said depth and said output signal.    
     
     
         2 . The apparatus of  claim 1  wherein said means for determining a depth of the sample comprises a sample depth analyser that measures depth of the sample.  
     
     
         3 . The apparatus of  claim 2  wherein the sample depth analyser is an ultra-sonic transmitting device.  
     
     
         4 . The apparatus of  claim 1  wherein the continuous linearly sweeping microwave signal varies in frequency between a range of about 0.10 GHz to 4.00 GHz.  
     
     
         5 . The method of  claim 4  wherein the continuous linearly sweeping microwave signal varies in frequency between a range inclusive of 1.25 GHz to 1.65 GHz.  
     
     
         6 . The apparatus of  claim 1  wherein the transmitter and receiver comprise respective antennas.  
     
     
         7 . The apparatus of  claim 1  wherein the microwave analyser comprises a microwave mixer that measures phase shift by receiving a portion of the transmitted signal and a portion of the received signal.  
     
     
         8 . The apparatus of  claim 7  wherein the microwave mixer generates an output signal comprising an oscillating voltage with a DC bias and frequency wherein a change in the DC bias or frequency is proportional to a change in velocity of the transmitted signal and provides a measure of a change in overall dielectric constant of the component in the sample.  
     
     
         9 . The apparatus of  claim 1  wherein the microwave analyser comprises a microwave amplitude detector that measures an amplitude of the received signal.  
     
     
         10 . The apparatus of  claim 1  wherein the random stratified sampling is performed using an algorithm programmed into the processor.  
     
     
         11 . The apparatus of  claim 1  wherein the processor is a microprocessor.  
     
     
         12 . The apparatus of  claim 1  wherein the component in the sample is carbon, salt, fat or protein.  
     
     
         13 . A method for measuring an amount of at least one component in a sample including the steps of: 
 (1) generating a continuous linearly sweeping microwave signal varying in frequency;    (2) transmitting the generated signal;    (3) receiving a received signal;    (4) measuring and analysing the generated signal and the received signal and generating an output signal; said output signal indicating phase and/or amplitude differences between the generated signal and the received signal;    (5) measuring a depth of the sample to provide a sample depth measurement; and    (6) processing the output signal and the sample depth measurement to determine the amount of the component in the sample.    
     
     
         14 . The method of  claim 13  wherein the continuous linearly sweeping microwave signal varies in frequency between a range of about 0.10 GHz to 4.00 GHz.  
     
     
         15 . The method of  claim 14  wherein the continuous linearly sweeping microwave signal varies in frequency between a range inclusive of 1.25 GHz to 1.65 GHz.  
     
     
         16 . The method of  claim 15  wherein the steps of transmitting and receiving signals is by respective antennas.  
     
     
         17 . The method of  claim 13  wherein phase shift is measured by a microwave mixer that receives a portion of the generated signal and a portion of the received signal.  
     
     
         18 . The method of  claim 17  wherein the output signal comprises an oscillating voltage with a DC bias that is proportional to both a change in microwave velocity and phase shift.  
     
     
         19 . The method of  claim 13  wherein attenuation of an amplitude of the generated signal is measured by an amplitude detector.  
     
     
         20 . The method of  claim 13  wherein the phase and/amplitude differences are measured by random stratified sampling of the received signal.  
     
     
         21 . The method of  claim 19  wherein the random stratified sampling is performed using an algorithm within a processor.  
     
     
         22 . The method of  claim 13  wherein the step of measuring a depth of the sample is by an ultra-sonic means.  
     
     
         23 . The method of  claim 13  wherein the processing is performed by a microprocessor.  
     
     
         24 . The method of  claim 13  wherein the component in the sample is carbon, fat, salt or protein.  
     
     
         25 . Use of the apparatus of  claim 1  to determine an amount of at least one component in a sample.  
     
     
         26 . Use of the apparatus of  claim 25  wherein the at least one component modifies the generated signal.  
     
     
         27 . Use of the apparatus of  claim 25  wherein the at least one component is carbon, salt, fat or protein.  
     
     
         28 . Use of the apparatus of  claim 25  where the sample is an ore, mineral, coal, flyash, nickel ore, alumina; chromium ore, wood chip; bulk food, textile, chemical, food product, sugar, pasta, coffee, peanuts, wheat, barley, beef jerky, kitty litter, paper, polystyrene or plastic.