Microwave measurement method of dielectric constant of grain pile
A dielectric constant and microwave measurement technology, which is applied in the direction of measuring device, specific gravity measurement, and electric variable measurement, can solve the problem that it is not very applicable, cannot measure the dielectric constant in the depth of grain piles, and cannot measure the change of grain pile density with depth And other issues
Active Publication Date: 2013-08-14
REMOTE SENSING APPLIED INST CHINESE ACAD OF SCI
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Problems solved by technology
However, this method is not very suitable for the densely packed grain in the national grain reserve
For the grain piles in the national grain reserve, ground penetrating radar can be used to measure on the surface of the grain piles, but this solution is greatly affected by the thickness of the grain and the reflected signal from the top of the warehouse, and it cannot measure the density of the grain piles with the depth. changing situation
Another technical solution is to use a time domain reflectometer (TDR) to insert into the surface of the grain pile for measurement, but the disadvantage of this technical solution is that it can only detect the dielectric constant information in a small area around the probe, and cannot measure the depth of the grain pile. The dielectric constant, and the insertion of the probe will cause a large disturbance to the measurement object within the effective range, resulting in inaccurate results
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[0036] The basic principle of the microwave method for measuring the dielectric constant of grain heaps provided by the present invention is as follows: it is considered that for the grains piled up in the national grain reserve, its relative electrical conductivity is very small, and the relative magnetic permeability is 1. Assuming that the relative permittivity of grain is ε, the propagation speed v of electromagnetic wave in grain is:
[0037] v = c / ϵ - - - ( 2 )
[0038] Among them, c is the propagation speed of electromagnetic wave in vacuum. If the velocity of the electromagnetic wave in the medium is measured, the dielectric constant of the medium can be calculated.
[0039] Since the velocity v of the electromagnetic wave is equal to the propagation distance d divided by the propagation time t, that is:
[0040] v=d / ...
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The invention discloses a microwave measurement method of a dielectric constant of a grain pile. The method is realized by a signal transmitter, a signal receiver, a transmission antenna and a reception antenna, wherein the transmission antenna is connected with the signal transmitter, the reception antenna is connected with the signal receiver, and both the transmission antenna and the receptionantenna are rod-shaped antennas. The method comprises the steps of: parallelly inserting the transmission antenna and the reception antenna in the grain pile at a certain distance to ensure that the transmission antenna and the reception antenna are located at certain positions below the grain surface, and the upper and lower ends are parallel and level; transmitting an electromagnetic wave by the signal transmitter through the transmission antenna, receiving the electromagnetic wave by the reception antenna and sending the electromagnetic wave to the signal receiver; and measuring to obtain a propagation time of the electromagnetic wave between the transmission antenna and the reception antenna and a distance between the transmission antenna and the reception antenna, so as to compute the dielectric constant of the grain pile.
Description
technical field [0001] The invention relates to a method for measuring the dielectric constant of a grain pile in a grain depot, and in particular to a method that utilizes the characteristic that the propagation speed of electromagnetic waves in a medium is affected by the dielectric constant of the medium in which it is located, and inserts a rod-shaped antenna into the grain pile in parallel, The method for measuring the dielectric constant by sending and receiving electromagnetic waves of a certain frequency (that is, microwaves, the same below) belongs to the technical field of material analysis and testing. Background technique [0002] In 1990, my country began to establish a national special grain reserve system. In order to strengthen the management and supervision of the national grain reserve, it is necessary to check the quantity and quality of its grain reserves. However, the grain in the national grain reserve is often piled up in various types of warehouses s...
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IPC IPC(8): G01R27/26G01N9/24
Inventor 吴炳方杨雷东蒙继华吴方明李强子
Owner REMOTE SENSING APPLIED INST CHINESE ACAD OF SCI