Multi-frequency radar for underground investigation

Claim 2

In a radar apparatus for detecting a distance from an emitter of the radar apparatus to an underground object to being detected by, reflections of electromagnetic waves emitted from said emitter which are reflected back by said object, a radar apparatus characterized in that it contains a device computes said distance based on Maxwell's equation relating to speed of propagation of the electromagnetic wave using received signals of two or more different frequencies.

Claim 3

A radar apparatus according to claim 1, characterized in that said device computing said distance determines the permittivity, permeability, or conductivity of a propagation medium using said received signals of two or more different frequencies, and computes said distance based on the result of said determination.

Claim 4

In a radar apparatus for detecting a distance from an emitter of the radar apparatus to an underground object to being detected comprising a control device which outputs a timing pulse for controlling the timing of transmitting pulse used for detecting a buried object in a ground, a transmitter which transmitts said transmitting pulse from said control device to said buried object through an antenna, a receiver for receiving a echo signal reflected back from said buried object, and a display device for displaying said echo signal from said receiver, a radar apparatus characterized in that further comprising a calculation device (6) for calculating time differences between said timing pulse from said control device (2) and receiving signals of two or more different frequencies from said receiver (5), a calculation device (7) for calculating said distance based on Maxwell's equation relating to speed of propagation of an electromagnetic wave using said time differences, and a control device (9) which makes said calculation device (7) start the calculation of said distance based on the signals of said time differences.

Claim 5

In a radar apparatus for detecting a distance from an emitter of the radar apparatus to an underground object to being detected comprising a control device which outputs a timing pulse for controlling the timing of transmitting pulse used for detecting a buried object in a ground, a transmitter which transmitts said transmitting pulse from said control device to said buried object through an antenna, a receiver for receiving a echo signal reflected back from said buried object, and a display device for displaying said echo signal from said receiver, a radar apparatus characterized in that further comprising a calculation device (6) for calculating time differences between said timing pulse from said control device (2) and receiving signals of two or more different frequencies from said receiver (5), a calculation device (7) for calculating said distance based on Maxwell's equation relating to speed of propagation of an electromagnetic wave using said time differences, and a control device (9) which makes said calculation device (7) start the calculation of said distance based on the signals of said time differences.

Claim 6

A radar apparatus according to claim 3, characterized in that said calculation device (7) determines the permittivity, permeability, or conductivity of a propagation medium using said receiving signals of two or more different frequencies, and computes from the result of said determination said distance.

Claim 7

A radar apparatus according to claim 3, characterized in' that said receiver (5) comprises a band-pass filter (11) comprising two or more different filters (fi, f 2 , f 3 ) which pass predetermined frequencies by the control signals of said control device (9), and a pulse generator (12) for generating pulse signals when the signals passed said filter (f 1 , f 2 , f 3 ) reach predetermined thresholds and outputting said signals to said calculation device (6).

Claim 8

A radar apparatus according to claim 3, characterized in that said transmitter (3) outputs a sinusoidal pulse to an antenna (8) whose intensity varies in a since wave according to the required receiving frequencies by receiving transmitting pulse from said control device (2).

Claim 9

A radar apparatus according to claim 3, characterized in that said transmitter (3) outputs a baseband pulse to an antenna (8) in which Fourier components of pulse electromagnetic waves emitted over a wide frequency range is used by receiving transmitting pulse from said control device (2).