| Any one of the geophysical methods uses physical characteristics difference of the medium to detect. In the detection of metal ore, the electric property difference between rock and metal ore body is the important standard in distinguishing the two. The transmitting speed of high-frequency electromagnetic wave emitted by ground penetrating radar (GPR) in medium is influenced by the dielectric permittivity. Therefore, the test of dielectric permittivity of rock is very important. Due to different sampling positions, environment and time of rock, for the rock with the same lithology, they will embody different dielectric property and conductance property. At the same time of referring to the rock physical property parameters, it is also very important to test the physical property of the sampling rock. For the rock in underground, due to the existence of the underground water and oil gas, it is impossible to get the dielectric permittivity of the rock framework without the influence of the water. As a result, it is necessary to test the dielectric permittivity of the rock in the lab.For the medium with strong metallic, electrical conductivity becomes the important factor measuring the electric property. For the rock, dielectric permittivity becomes the important parameter representing electric property.There are many kinds of methods of testing the dielectric permittivity of the medium. Generally speaking, there are short-circuit waveguide method, coaxial transmission / reflection method, open coaxial probe method, metal resonant cavity perturbation method, free-space method and parallel-plate capacitor method, etc. Different testing methods have different traits. Open coaxial probe method is popular since there is no damage and the making technology of the sample is easy. This thesis applies the open coaxial probe method to test the dielectric permittivity of the rock.Open coaxial probe method has many kinds of modeling patterns, among which, the all wave analyzing model of the spectral domain and the quasi-static spectral domain model are the most advanced. The former is the theoretical pattern obtained according to the electromagnetic field theory. The latter ignores the influence of the high pattern on the reflection coefficient near the hole-mouth in the terminal of the coaxial detector. In theory, the full wave pattern can be used to measure the dielectric property of the materials. However, in the theory as well as the experiment, we can find the modeling error caused by the ignorance to the high pattern equals to the measuring error of the reflection coefficient. Therefore, while the required precision is high, the full wave can be used and the reflection coefficient has certain error. The quasi-static model is applied while quickly treating the data.This thesis develops a set of rock testing system for dielectric permittivity based on quasi-static spectral domain model. The hardware includes Vector Network Analyzer (Aglilent E5071B), coaxial probe and minerals constitute holder.In arithmetic, this thesis mainly does the research on the following issues:(1) Building up quasi-static spectral domain model: get the relation between the reflection coefficient and dielectric permittivity by using continuity property of electromagnetic field of touching borderline.(2) There is Bessel functions integral of 0-∞in the model. Due to the particularity of Bessel functions, the Bessel functions integral should be taken into consideration. For this integral issue, the numerical solution should be used. The issue that the upper limit is∞should be considered. Compare the upper limit values based on different integrals. When the upper limit is 12500, it can meet the demand of integral convergence. (3) Calibration:Calibration can be done only by the end of tie-in of coaxial cable due to the use of net analyzing meter to calibrate the cable. This is different from the real reflecting side. Calibration can be done through three error source ( ed is limited directional error;er is frequency tracking error;es is the equivalent source mismatch error). We can calibrate the reflecting side till the open flange disc and touching side through reflection coefficient and relations between the reflection coefficients (operator composed of three error sources).(4) Refutation process: design the aiming function to make the value of the aiming function the minimum through applying pure optimization. This thesis tests the standard materials with different known dielectric permittivity: air, PTFE and water. The mean variation is 0.8%, 2.3% and 4.1%.(5) In addition, as comparison, transmission/reflection is used to test the rock dielectric permittivity and Shen and NRW are used to compute. For the ore with the high quality, this method is not applicable very well. The yield rate of the rock sample is low. It is impossible to test according to the lot quickly. Therefore, open coaxial probe method is the best choice.The author tests the dielectric permittivity of sample of Changren Jilin Nickel Copper, Lead-Zinc Mine Gully yellow Chifeng, Chifeng molybdenum Nianzishan groove with open coaxial probe method. Since the medium constituting the rock ore is even, we apply the average of many samples of the same kind to reduce the testing and computing error. At the same time, we can evaluate the whole effect of rock ore of the same kind better through this way. Through the comparison between the real components of the dielectric permittivity, in the case that rock sample processing is even, we can distinguish the difference between the wall rock and rock ore. The shattered molybdenum ore with high hardness can be treated as the mixture of air and ore frame. It is considered as the anisotropic material with the material in the air. Since there is the air whose dielectric permittivity is 1, dielectric permittivity of the anisotropic material will be reduced. It can be predicted that when there is a lot of ore underground, due to the water and oil gas, dielectric permittivity of the whole ore is different from that tested in practice with air gap and from real result of rock ore skeleton. This conforms to the dielectric property of the rock ore.In conclusion, based on the open coaxial probe method of spectral domain, the computing precision in arithmetic is very good. In the case of strictly controlling the measuring error, it can test the rock ore fast. In addition, the technology for making the sample of rock ore is simple. This is an advantage comparing with other means in testing the dielectric permittivity.
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