Method and apparatus for a rotating cutting drum or arm mounted with paired opposite circular polarity antennas and resonant microstrip patch transceiver for measuring coal, trona and potash layers forward, side and around a continuous mining machine

A method for determining the thickness of underground geologic deposits over twelve inches in thickness, the method comprising the steps of:

• transmitting a series of synthetic-pulse stepped-frequency ground-penetrating radar signals from a circularly polarized microwave microstrip transmitting antenna into an underground geologic deposit;
• receiving a reflected series of signals with a second microwave microstrip receiving antenna having a circular polarization opposite to said transmitting antenna;
• using a fast Fourier transform to generate amplitude versus time data;
• signal processing said data to determine a time "t" between a first amplitude peak corresponding to a near interface of said underground geologic deposit and a second amplitude peak corresponding to a far interface of said underground geologic deposit, where "t" is the travel time of said transmitted signals reflected through the thickness of said underground geologic deposit;
• and
• estimating the dimension of said thickness of said underground geologic deposit by multiplying the speed of light by the time "t" and dividing the product by the square root of a predetermined dielectric constant of the material of said underground geologic deposit.

A instrumentation system for determining the thickness of underground geologic deposits from a cutting drum of a mining machine operating in explosive atmospheres, the system comprising:

• a power generator providing for the ignition-free generation of electrical power in an explosive atmosphere from an alternating current (AC) alternator mechanically driven by at least one of a water turbine and a swinging counterweight set in motion by a rotating cutting drum of a mining machine:
• an antenna assembly including a planar circularly-polarized transmitter antenna and a planar circularly-polarized receiver antenna mounted side-by-side in a common plane and of opposite circular polarizations and mounted near an outer perimeter of said rotating cutting drum and mounted behind a protective skin;
• a transmitter connected to said transmitter antenna and providing for synthetic pulse frequency-stepped ground-penetrating radar signals over a range of frequencies, and connected to receive operating power from the power generator;
• a receiver connected to said receiver antenna and providing for measurements of a radio-illuminated underground material layer based on the amplitude and phase of received signals, and connected to receive operating power from the power generator;
• and
• estimation means connected to the receiver for interpreting said amplitude and phase of said received signals into estimates of the thickness of an underground layer of geologic material proximate to the antenna assembly based on predetermined dielectric constants of said underground material layer, and connected to receive operating power from the power generator.