Calibration detection device based on rectangular waveguide
By using a calibration and detection device based on a rectangular waveguide, the problems of conversion factor and isotropy in the calibration of low-frequency electric field probes were solved, and the accurate measurement of SAR values was achieved, meeting the testing requirements at a frequency of 600MHz.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2026-03-20
AI Technical Summary
Existing technologies struggle to effectively calibrate the conversion factor and isotropy of electric field probes in the low-frequency band, leading to inaccurate SAR value measurements.
A calibration and detection device based on a rectangular waveguide is adopted, which includes a rectangular cavity, a dielectric substrate and a rectangular waveguide, filled with tissue fluid. Impedance matching is achieved through the dielectric substrate, and a signal source and stabilization circuit are connected to meet the SAR value measurement requirements at a frequency of 600MHz.
It achieves accurate measurement of SAR values at a frequency of 600MHz, meets the conversion factor and isotropic calibration requirements of probe calibration, and improves test accuracy.
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Figure CN224019901U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of detection, in particular to a calibration detection device based on a rectangular waveguide. BACKGROUND
[0002] In recent years, with the rapid development of wireless body area networks, portable electronic products such as mobile phones, smart watches, interphones, and tablets have been widely introduced into the market. These products can mostly be connected to other devices through wireless signals to interact with data or voice, thus generating corresponding electromagnetic radiation. Excessive electromagnetic radiation of wireless information terminals can have a great impact on the human body. In order to ensure the safe operation of wireless communication devices and maintain the vital interests of users, governments and relevant telecommunications regulatory agencies have made clear regulations that the impact of electromagnetic radiation on the human body must meet safety standards before being put into use.
[0003] The test of the specific absorption rate (SAR) value of the human body is necessary for advanced laboratory tests, which is highly strategic and challenging. At present, the laboratory test environment and probe calibration system for the SAR value in China still needs to be further strengthened. At the present stage, the traditional low-frequency probe calibration is usually placed in a TEM cell, which can generally only evaluate the frequency response and linearity of the electric field probe in free space, and it is difficult to solve the problems of conversion factor and isotropic calibration. SUMMARY
[0004] To overcome the above-mentioned shortcomings,
[0005] One of the purposes of the present application is to provide a calibration detection device based on a rectangular waveguide.
[0006] In order to achieve the above purposes, the present application adopts the following technical solutions:
[0007] A calibration detection device based on a rectangular waveguide, which is used for testing occasions with a center frequency of 600MHz, comprises:
[0008] A hollow chamber in a rectangular shape, one side end of the chamber is provided with a dielectric substrate, the side of the dielectric substrate away from the chamber is provided with a rectangular waveguide, the rectangular waveguide comprises a shell, the shell is filled with tissue fluid, one side of the shell has an opening part, and the opening part side is connected with the dielectric substrate;
[0009] One side of the chamber has a connecting end, and the first connecting end is used for connecting a signal source to be tested.
[0010] The rectangular waveguide is impedance-matched through the dielectric substrate.
[0011] Preferably, the connecting end comprises an SMA connector for connecting a signal source.
[0012] Preferably, the connecting end is connected to a stabilizing circuit, and the stabilizing circuit is electrically connected to the power meter.
[0013] Preferably, the medium substrate is made of polytetrafluoroethylene fiberglass cloth ceramic filled plate material, and the relative dielectric constant is 6-7.
[0014] Preferably, the thickness of the medium substrate is 45-47mm.
[0015] Preferably, the rectangular waveguide includes an aluminum alloy shell with a thickness of 3-5mm.
[0016] Preferably, the medium substrate is provided with a feeding circuit away from the side of the rectangular waveguide.
[0017] Preferably, the rectangular waveguide includes an aluminum alloy shell with a thickness of 4mm.
[0018] Advantages
[0019] Compared with the prior art, the calibration detection device provided by the present application can work in a 600MHz field and calculate the SAR value based on the rectangular waveguide, and meets the relevant requirements for evaluating the calibration of the tissue liquid probe. BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings are used to provide an understanding of the technical solutions of the present disclosure, and constitute a part of the specification, and are used together with the embodiments of the present disclosure to explain the technical solutions of the present disclosure, and do not constitute a limitation on the technical solutions of the present disclosure. The shapes and sizes of the components in the drawings do not reflect the true proportions, and the purpose is only to schematically illustrate the content of the present application.
[0021] Figure 1 It is a perspective structural schematic view of the detection device of the embodiment of the present application;
[0022] Figure 2 It is a top view schematic view of the detection device of the embodiment of the present application;
[0023] Figure 3 It is a circuit function module schematic view of the detection device of the embodiment of the present application connected to the signal source;
[0024] Figure 4 It is an electric field intensity simulation diagram in the rectangular waveguide of the embodiment of the present application;
[0025] Figure 5 It is a S parameter measurement schematic view of the rectangular waveguide of the embodiment of the present application after adding tissue liquid. DETAILED DESCRIPTION
[0026] The above solutions are further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present application and are not intended to limit the scope of the present application. The implementation conditions used in the examples can be further adjusted according to the specific conditions of the manufacturer, and the implementation conditions not mentioned are usually the conditions in the conventional experiments.
[0027] Unless otherwise defined, technical terms or scientific terms used in the embodiments of the present disclosure shall have the ordinary meaning understood by a person of ordinary skill in the art to which the present application pertains. The terms "first", "second", and similar terms used in the embodiments of the present disclosure do not denote any order, quantity, or importance, but are used to distinguish different constituent parts. The terms "include", "contain", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this document, "electrically connected" includes the case where the constituent elements are connected together through an element having a certain electrical effect. The element having a certain electrical effect is not particularly limited as long as it can perform the transmission of electrical signals between the constituent elements to be connected. The element having a certain electrical effect may, for example, be an electrode or a wiring, or a switching element such as a transistor, or another functional element such as a resistor, an inductor, or a capacitor. The terms "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships can also change accordingly.
[0028] In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "middle", and the like is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements, or constituent parts to have a particular orientation, or to be constructed and operated in a particular orientation.
[0029] At present, the electric field probe of the low frequency band is usually placed in a TEM cell (TEM cell, also known as transverse electromagnetic wave chamber, is a special rectangular cross-section transmission line composed of an outer conductor with a horn-shaped gradual contraction at both ends and an inner conductor with a strip-shaped partition plate in the middle. In the frequency range of direct current to 200 MHz, the transverse electromagnetic wave chamber is mainly used for radio frequency electromagnetic field radiation immunity test and radio frequency electromagnetic field emission measurement of electronic equipment), and such calibration can only calibrate the frequency response and linearity of the probe, and it is difficult to solve the problems of conversion factor and isotropy.
[0030] Based on this application proposes a kind of calibration detection device based on rectangular waveguide, it can work in the occasion of 600MHz to carry out accurate measurement, can test the corresponding SAR value (Specific Absorption Ratio, SAR) indicates that unit time unit mass of substance absorbs electromagnetic radiation energy.For every 6 minutes, the SAR value is generally used internationally to measure the thermal effect of terminal radiation, per kg of human tissue absorbs electromagnetic radiation energy (watt).With mobile phone radiation as an example, S AR refers to the ratio of radiation absorbed by the soft tissue of head, the less SAR value, the less amount of radiation absorbed by brain), effectively calibrating the conversion factor and isotropy of probe stick.This detection device meets the relevant requirements of evaluating tissue fluid probe calibration and realizes the ability of calculating SAR value.The bandwidth of the working frequency band of the rectangular waveguide can reach 120MHz, which can effectively solve the related requirements of low-frequency probe calibration.
[0031] Down to combine the attached Figures 1-5 The calibration detection device based on rectangular waveguide proposed in the application will be described.
[0032] The detection device comprises:
[0033] The hollow chamber 110 is rectangular, and one side end is provided with a dielectric substrate 120, and the side away from the chamber of the dielectric substrate 120 is provided with a rectangular waveguide 130, which comprises a shell filled with tissue fluid (not shown in the figure), and the dielectric substrate 120 seals the rectangular waveguide 130 (so that the tissue fluid does not enter the chamber 110).One side of the dielectric substrate is provided with a feed circuit, and better impedance matching can be achieved through the dielectric substrate.
[0034] The detection device can work in the occasion of 600MHz, and meet the related calibration requirements of the conversion factor and isotropy of probe stick calibration.
[0035] One side of the chamber 110 has a connection end 111, which is used to connect the signal source.Prefect, the connection end 111 includes SMA joint (also known as SMA connector, Sub-Miniature A), to ensure the signal stability of signal source, signal stabilization circuit (such as Figure 3 As shown) is arranged at this position, and the stabilization circuit is electrically connected with the power meter, and the signal condition of signal source is checked through the power meter during measurement.
[0036] The medium substrate 120 adopts polytetrafluoroethylene fiberglass cloth ceramic filling plate material, and the relative dielectric constant is between 6 and 7. In the embodiment, the relative dielectric constant is 6.15. The thickness of the medium substrate is between 45 mm and 47 mm. In the embodiment, the thickness of the medium substrate is 46.8 mm, so that better impedance matching can be realized when the center frequency is 600 MHz (frequency band 556-682 MHz).
[0037] The shell 131 of the rectangular waveguide 130 adopts aluminum alloy material, and the thickness is between 3 mm and 5 mm. Preferably, the thickness is 4 mm. The shell 131 is in a rectangular shape (preferably, the inner diameter size length is 381 mm (y direction), the width is 190.5 mm (z direction), and the height is 800 mm (x direction), which matches the shape of the cavity 110. Considering the transmission of the main mode TE10 mode in the waveguide and the electromagnetic reflection of the inner wall of the cavity filled with tissue fluid, the measurement accuracy of the SAR value is affected, the tissue fluid cavity is set to be greater than 3 times the skin depth when working at 600 MHz, and the height of the tissue fluid cavity is set to 200 mm (x direction). The electric field intensity diagram in the tissue fluid is as shown in Figure 2 .
[0038] The tissue fluid ratio in the rectangular waveguide 130 is as follows:
[0039] SAR is the electromagnetic power absorbed or consumed by the unit mass of human tissue in the test, and the test is carried out in an environment simulating the human body shape. When the dielectric constant and conductivity of the tissue fluid are matched with the relevant standard parameters of the human head tissue model at 600 MHz (center frequency), the SAR test is a key part. For different frequencies, the dielectric constant and conductivity of the tissue fluid are also different. In the embodiment, deionized water, sucrose, hydroxyethyl cellulose, sodium chloride, and preservatives are matched in a certain proportion to simulate the dielectric constant and conductivity of the human head tissue at the center frequency of 600 MHz. The actual matching completes the dielectric constant of the solution to be 44.07, and the conductivity is 0.84. The electric field intensity simulation in the tissue fluid in the rectangular waveguide is as shown in Figure 4 .
[0040] In order to verify the accuracy of the simulation model, the designed rectangular waveguide is processed and tested. In order to ensure the stability of the field intensity and the accuracy of the actual SAR test, the net incident power transmitted to the waveguide needs to be accurately measured, and the stable circuit as shown in Figure 3 is configured. The S parameter of the rectangular waveguide after adding the tissue fluid is measured as shown in Figure 5 . The electric field intensity of the rectangular waveguide is measured as shown in Figure 5The reflection coefficient of the waveguide port is -14.88 dB at 600 MHz, and the net input power of the rectangular waveguide is 30.38 dBm. The input power of the port is monitored in real time by using a directional coupler. The SAR values at different depths from 2 mm to 10 mm are measured with the center of the rectangle as x=0, y=0, and the bottom surface of the tissue liquid cavity as z=0, with a step of 1 mm. Considering the influence of environmental factors, 5 groups of data are compared. The deviation between the simulation and the actual measured SAR value is within ±15%, which proves that the design achieves a good computable SAR value standard waveguide. The deviation between the simulation (modeled and simulated using HFSS (High Frequency Structure Simulator)) and the actual test is shown in Table 1,
[0041]
[0042] Table 1
[0043] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.
[0044] The above-described embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent conversion or modification made in the spirit and essence of the present application should be covered within the protection scope of the present application.
Claims
1. A calibration and detection device based on a rectangular waveguide, used for testing at a center frequency of 600MHz, characterized in that, include: A rectangular hollow chamber has a dielectric substrate disposed at one end of the chamber and a rectangular waveguide disposed on the side of the dielectric substrate away from the chamber. The rectangular waveguide includes a housing, which is filled with tissue fluid. One side of the housing has an opening, which is connected to the dielectric substrate. One side of the chamber has a connection end, which is used to connect to a signal source. The rectangular waveguide is impedance matched by the dielectric substrate.
2. The detection device as described in claim 1, characterized in that, The connection end includes an SMA connector for connecting to a signal transmission source.
3. The detection device as described in claim 2, characterized in that, The connection terminal is connected to a stabilizing circuit, and the stabilizing circuit is electrically connected to a power meter.
4. The detection device as described in claim 1, characterized in that, The dielectric substrate is made of polytetrafluoroethylene fiberglass cloth ceramic filler plate material.
5. The detection device as described in claim 4, characterized in that, The relative permittivity of the dielectric substrate is between 6 and 7.
6. The detection device as described in claim 4, characterized in that, The thickness of the dielectric substrate is between 45-47 mm.
7. The detection device as described in claim 1, characterized in that, The rectangular waveguide includes an aluminum alloy housing with a thickness of 3-5 mm.
8. The detection device as described in claim 1, characterized in that, A power supply circuit is provided on the side of the dielectric substrate away from the rectangular waveguide.