CN107994956B - Terminal, radio frequency front-end device and electromagnetic wave absorption ratio adjusting method and system thereof - Google Patents

Terminal, radio frequency front-end device and electromagnetic wave absorption ratio adjusting method and system thereof Download PDF

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CN107994956B
CN107994956B CN201711224202.4A CN201711224202A CN107994956B CN 107994956 B CN107994956 B CN 107994956B CN 201711224202 A CN201711224202 A CN 201711224202A CN 107994956 B CN107994956 B CN 107994956B
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radio frequency
antenna
power
impedance
scene
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CN107994956A (en
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李伟
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Xian Yep Telecommunication Technology Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/101—Monitoring; Testing of transmitters for measurement of specific parameters of the transmitter or components thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/20—Monitoring; Testing of receivers

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
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Abstract

The invention discloses a terminal, a radio frequency front-end device and an electromagnetic wave absorption ratio adjusting method and system thereof. The radio frequency front-end device comprises at least one antenna, and the electromagnetic wave absorption ratio adjusting method comprises the following steps: detecting the impedance of an antenna in a working state in the at least one antenna; determining a UI scene where the radio frequency front-end device is located according to the detected impedance; acquiring the maximum radio frequency transmitting power of the antenna in the working state in the UI scene, wherein the maximum radio frequency transmitting power accords with the electromagnetic wave absorption ratio index; and reducing the radio frequency transmission power of the antenna in the working state below the corresponding maximum radio frequency transmission power. The invention realizes the control of the radio frequency emission power of the antenna under different UI scenes through the real-time detection of the impedance of the antenna so as to meet the SAR adjustment requirement and accord with the SAR index.

Description

Terminal, radio frequency front-end device and electromagnetic wave absorption ratio adjusting method and system thereof
Technical Field
The invention belongs to the technical field of radio frequency, and particularly relates to a terminal, a radio frequency front-end device, and an electromagnetic wave absorption ratio adjusting method and system thereof.
Background
The electromagnetic wave absorption ratio is an important index for measuring the radiation of wireless terminal products such as mobile phones and the like to human bodies. The electromagnetic wave Absorption ratio (SAR) is the electromagnetic power absorbed or consumed by a unit mass of human tissue, in W/kg, and represents the influence of radiation on the human body, the lower the SAR value, the less radiation is absorbed.
For the SAR standard, CE certification (european union) and FCC (federal communications commission) have established different limits and test methods, respectively, and most of other countries or regions use the two main standards for reference. The FCC standard is relatively more stringent, with the adopted countries being the united states, canada, mexico, india, etc., and the adopted limit being 1.6W/kg calculated as 19 small cubes; the CE standard is relatively widely adopted in countries and regions such as european union, china, thailand, japan, and southeast asia, and the adopted limit value is 2.OW/kg calculated in 109 small cubic blocks. The two limits are different from each other in size and calculation method, and the radiation size possibly causing harm is considered when the radiation limit is determined, so that the radiation risk is within a controllable range no matter which test and authentication is carried out.
With the evolution of wireless communication technology, the SAR of the antenna is required to be higher and higher while the performance of the antenna is considered. In the conventional technology, an SAR sensor or other sensor for detecting the approach of a human body is usually added to track the environment around the antenna, so as to adjust the radio frequency transmission power of the antenna to reduce SAR. However, there are still many limitations in the solutions, and a phenomenon that is not in accordance with actual expectations occurs in many scenarios, for example, specifications require SAR of six surfaces of a test terminal, it is difficult to determine which surface is close to a human body through an existing sensor, and it is difficult to accurately detect and control a conventional SAR reduction scheme in a multi-antenna transmission state such as MIMO (Multiple-Input Multiple-Output).
Disclosure of Invention
The invention provides a terminal, a radio frequency front-end device and an electromagnetic wave absorption ratio adjusting method and system thereof, aiming at overcoming the defect that accurate detection and control of SAR are difficult to realize due to the fact that an SAR sensor or other sensors for detecting the approach of a human body are adopted to track the environment around an antenna in the prior art.
The invention solves the technical problems through the following technical scheme:
the invention provides an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device, wherein the radio frequency front end device comprises at least one antenna, and the electromagnetic wave absorption ratio adjusting method comprises the following steps:
detecting the impedance of an antenna in a working state in the at least one antenna;
determining a UI scene where the radio frequency front-end device is located according to the detected impedance;
acquiring the maximum radio frequency transmitting power of the antenna in the working state in the UI scene, wherein the maximum radio frequency transmitting power accords with the electromagnetic wave absorption ratio index;
and reducing the radio frequency transmission power of the antenna in the working state below the corresponding maximum radio frequency transmission power.
Preferably, determining the UI scene where the radio frequency front end device is located according to the detected impedance includes:
searching a pre-stored table, wherein the pre-stored table comprises impedance of each antenna in the at least one antenna in a working state under at least one preset UI scene;
and finding out the UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table.
Preferably, the pre-stored table further comprises: maximum radio frequency transmitting power corresponding to the UI scenes one by one;
acquiring the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index under the UI scene, wherein the maximum radio frequency transmitting power comprises the following steps:
and finding out the maximum radio frequency transmitting power of the antenna in the working state according with the electromagnetic wave absorption ratio index from the pre-stored table according to the determined UI scene.
Preferably, the pre-stored table further includes a radio frequency power back-off amount of each antenna in the at least one antenna in at least one preset UI scenario, where the radio frequency power back-off amount is not less than a radio frequency power minimum back-off amount;
the minimum back-off Δ P of the radio frequency power is P-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxThe maximum radio frequency transmitting power is the maximum radio frequency transmitting power which is in accordance with the electromagnetic wave absorption ratio index when the antenna is in a working state under the UI scene, and the maximum transmitting power is the maximum radio frequency transmitting power which is pre-stored in a pre-stored table and corresponds to the UI scene one by one;
the method for adjusting the electromagnetic wave absorption ratio further comprises the steps of obtaining the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index in the UI scene and reducing the actual radio frequency transmitting power of the antenna in the working state to be below the corresponding maximum radio frequency transmitting power, and replacing the steps with the steps of:
and searching the pre-stored table, and reducing the radio frequency transmitting power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene.
Preferably, when the number of antennas in the active state is detected to be m and m > 1, the minimum back-off Δ P of the radio frequency power is equal toP-Pmax-Δs，Δs＝-5*log(1/m)。
Preferably, the pre-stored table further includes an execution code to be invoked for reducing a corresponding radio frequency power back-off of each antenna of the at least one antenna in at least one preset UI scenario;
and reducing the radio frequency transmission power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene, and calling and executing the corresponding execution code.
Preferably, the method for adjusting an electromagnetic wave absorption ratio further includes:
monitoring the radio frequency transmission power of the antenna in the working state in the at least one antenna, and triggering and continuously detecting the impedance of the antenna in the working state in the at least one antenna when the starting condition is met;
the starting condition is that the monitored radio frequency transmitting power is larger than a preset high-power threshold, wherein the high-power threshold is smaller than or equal to the minimum value of the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under all UI scenes.
Preferably, the step of detecting the impedance of the antenna in the working state in the at least one antenna is stopped when the termination condition is satisfied;
the termination condition is that the monitored radio frequency transmission power is smaller than a preset small power threshold, wherein the small power threshold is smaller than the high power threshold.
Preferably, the pre-stored table includes an impedance area when each antenna of the at least one antenna is in a working state in at least one preset UI scene, where the impedance area is a set of positions of actually measured impedance of the antenna on a Smith chart in the UI scene;
detecting an impedance of an active antenna of the at least one antenna, comprising: detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart;
finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table, wherein the UI scene comprises the following steps: and determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area.
The Smith chart is a calculated graph in which a family of iso-circles of normalized input impedance (or admittance) is plotted on a scattering plane of the reflection system. The impedance matching chart is a chart used for motor and electronic engineering and is mainly used for impedance matching of transmission lines.
Preferably, in the pre-stored table, if the impedance regions corresponding to different UI scenes overlap or have a distance smaller than a preset distance threshold, the different UI scenes are combined into one UI scene, and the impedance region corresponding to the combined UI scene covers the sum of the impedance regions corresponding to the different UI scenes.
The present invention also provides an electromagnetic wave absorption ratio adjustment system for a radio frequency front end device, the radio frequency front end device including at least one antenna, the electromagnetic wave absorption ratio adjustment system including:
the impedance detection unit is used for detecting the impedance of the antenna in a working state in the at least one antenna;
the control processing unit is used for determining a UI scene where the radio frequency front-end device is located according to the detected impedance and acquiring the maximum radio frequency transmitting power of the antenna in a working state meeting the electromagnetic wave absorption ratio index under the UI scene;
and the power adjusting unit is used for reducing the radio frequency transmitting power of the antenna in the working state to be lower than the corresponding maximum radio frequency transmitting power.
Preferably, the electromagnetic wave absorption ratio adjusting system further comprises a pre-stored table storage unit;
the pre-stored table storage unit is used for storing a pre-stored table, and the pre-stored table comprises impedance of each antenna in the at least one antenna in a working state under at least one preset UI scene;
determining the UI scene where the radio frequency front-end device is located through the detected impedance, wherein the UI scene comprises the following steps:
and searching a pre-stored table, and finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table.
Preferably, the pre-stored table further comprises: maximum radio frequency transmitting power corresponding to the UI scenes one by one;
acquiring the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index under the UI scene, wherein the maximum radio frequency transmitting power comprises the following steps:
and finding out the maximum radio frequency transmitting power of the antenna in the working state according with the electromagnetic wave absorption ratio index from the pre-stored table according to the determined UI scene.
Preferably, the pre-stored table further includes a radio frequency power back-off amount of each antenna in the at least one antenna in at least one preset UI scenario, where the radio frequency power back-off amount is not less than a radio frequency power minimum back-off amount;
the minimum back-off Δ P of the radio frequency power is P-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxThe maximum radio frequency transmitting power is the maximum radio frequency transmitting power which is in accordance with the electromagnetic wave absorption ratio index when the antenna is in a working state under the UI scene, and the maximum transmitting power is the maximum radio frequency transmitting power which is pre-stored in a pre-stored table and corresponds to the UI scene one by one;
the control processing unit is further configured to obtain a radio frequency power back-off quantity of the antenna in a working state in the UI scene by searching the pre-stored table;
the power adjusting unit is further configured to reduce the radio frequency transmission power of the antenna in the working state by the obtained radio frequency power back-off amount.
Preferably, when the control processing unit detects that the number of antennas in the operating state is m and m > 1, the minimum back-off Δ P of the radio frequency power is P-Pmax-Δs，Δs＝-5*log(1/。
Preferably, the pre-stored table further includes an execution code to be invoked for reducing a corresponding radio frequency power back-off of each antenna of the at least one antenna in at least one preset UI scenario;
and the power adjusting unit reduces the radio frequency transmitting power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene by calling and executing the corresponding execution code.
Preferably, the electromagnetic wave absorption ratio adjusting system further comprises a power monitoring unit;
the power monitoring unit is used for monitoring the radio frequency transmission power of an antenna in a working state in the at least one antenna, and triggering the impedance detection unit to continuously detect the impedance of the antenna in the working state in the at least one antenna when an initial condition is met;
the starting condition is that the monitored radio frequency transmitting power is larger than a preset high-power threshold, wherein the high-power threshold is smaller than or equal to the minimum value of the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under all UI scenes.
Preferably, the power monitoring unit is further configured to control the impedance detection unit to stop detecting the impedance of the antenna in the working state in the at least one antenna when a termination condition is met;
the termination condition is that the monitored radio frequency transmission power is smaller than a preset small power threshold, wherein the small power threshold is smaller than the high power threshold.
Preferably, the pre-stored table includes an impedance area when each antenna of the at least one antenna is in a working state in at least one preset UI scene, where the impedance area is a set of positions of actually measured impedance of the antenna on a Smith chart in the UI scene;
detecting an impedance of an active antenna of the at least one antenna, comprising: detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart;
finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table, wherein the UI scene comprises the following steps: and determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area.
Preferably, in the pre-stored table, if the impedance regions corresponding to different UI scenes overlap or have a distance smaller than a preset distance threshold, the different UI scenes are combined into one UI scene, and the impedance region corresponding to the combined UI scene covers the sum of the impedance regions corresponding to the different UI scenes.
The invention also provides a radio frequency front-end device, which comprises at least one antenna and an electromagnetic wave absorption ratio adjusting system with any combination of the above preferable conditions.
The invention also provides a terminal which comprises the radio frequency front-end device.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The positive progress effects of the invention are as follows: the invention realizes the control of the radio frequency emission power of the antenna under different UI scenes through the real-time detection of the impedance of the antenna so as to meet the SAR adjustment requirement and accord with the SAR index.
Drawings
Fig. 1 is a flowchart of an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device according to embodiment 1 of the present invention;
fig. 2 is a flowchart of an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device according to embodiment 2 of the present invention;
fig. 3 is a flow chart of a further optimized method for adjusting an electromagnetic wave absorption ratio of a radio frequency front end device according to embodiment 2 of the present invention;
FIG. 4 is a schematic diagram of a high power threshold and a low power threshold;
fig. 5 is a flowchart of an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device according to embodiment 3 of the present invention;
FIG. 6 is a schematic diagram of the impedance region of the antenna under n UI scenes;
fig. 7 is a flowchart of an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device according to embodiment 4 of the present invention;
fig. 8 is a flowchart of an electromagnetic wave absorption ratio adjusting method of a radio frequency front end device according to embodiment 5 of the present invention;
fig. 9 is a system block diagram of an electromagnetic wave absorption ratio adjustment system of a radio frequency front end device according to embodiment 6 of the present invention;
fig. 10 is a system block diagram of an electromagnetic wave absorption ratio adjustment system of a radio frequency front end device according to embodiment 7 of the present invention;
fig. 11 is a system block diagram of an electromagnetic wave absorption ratio adjustment system of a radio frequency front end device according to embodiment 8 of the present invention;
fig. 12 is a schematic block diagram of detecting the impedance of the antenna according to embodiment 10 of the present invention;
fig. 13 is a schematic block diagram of a bidirectional coupler according to embodiment 10 of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
Fig. 1 shows an electromagnetic wave absorption ratio adjustment method of the rf front-end device of the present embodiment. The radio frequency front-end device comprises at least one antenna, and the electromagnetic wave absorption ratio adjusting method comprises the following steps:
step 101, detecting the impedance of the antenna in the working state in the at least one antenna.
And step 102, determining the UI scene where the radio frequency front-end device is located according to the detected impedance.
And 103, acquiring the maximum radio frequency transmitting power of the antenna in the working state in the UI scene, wherein the maximum radio frequency transmitting power meets the electromagnetic wave absorption ratio index.
And 104, reducing the radio frequency transmitting power of the antenna in the working state to be lower than the corresponding maximum radio frequency transmitting power.
The UI scene represents a use scene of a user, for example, the user holds the radio frequency front end device or a terminal equipped with the radio frequency front end device by the left hand, holds the radio frequency front end device by the right hand, or a terminal equipped with the radio frequency front end device by the right hand, and the like, and impedance of an antenna in the radio frequency front end device changes with different UI scenes; the electromagnetic wave absorption ratio index (hereinafter referred to as SAR index) may be an SAR limit that meets CE certification standards, may also be an SAR limit that meets FCC standards, or may be an SAR value that meets other standards or is set according to a certain specific requirement, which is not specifically limited in the present invention.
When the radio frequency transmission power of the antenna in the working state is reduced to be lower than the corresponding maximum radio frequency transmission power, the SAR of the radio frequency front-end device is reduced and accords with the SAR index corresponding to the current UI scene. The electromagnetic wave absorption ratio adjusting method of this embodiment determines the current UI scene through the impedance of the antenna, and further determines the maximum radio frequency transmission power corresponding to the current UI scene, and then reduces the SAR by reducing the radio frequency transmission power of the antenna, so that the current SAR of the radio frequency front-end device conforms to the SAR index.
Example 2
This example is a further explanation of the electromagnetic wave absorption ratio adjusting method of the present invention based on example 1.
In the actual use process of the radio frequency front end device, the radio frequency transmission power of the antenna usually fluctuates, and the SAR does not always exceed the SAR index continuously, so that the steps 101 to 104 do not need to be continuously executed in order to avoid the repeated adjustment of the radio frequency transmission power and occupy excessive system resources, and the steps 101 to 104 only need to be executed when the radio frequency transmission power is too large and the SAR exceeds the SAR index.
In this embodiment, the electromagnetic wave absorption ratio adjustment method presets the high-power threshold Pht, and the monitored radio frequency transmission power of the antenna is greater than the high-power threshold Pht as the initial condition of the triggering step 101. Since the maximum rf transmit power of the antenna may be different in various UI scenarios, in order to ensure the consistency of adjustment, the high-power threshold Pht is preferably set to be less than or equal to the minimum value of the maximum rf transmit power that meets the electromagnetic wave absorption ratio index when the antenna is in the operating state in all UI scenarios. For example, set the high power threshold Pht min { P ═max1，Pmax2，……，Pmaxn } -0.5 (dB). Wherein n is the total number of the preset UI scenes; pmaxAnd i is the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under the ith UI scene. Of course, the present invention is not limited to this, and the high power threshold Pht may be set to other values according to actual requirements.
The electromagnetic wave absorption adjustment method of the present embodiment is a flow as shown in fig. 2, and specifically includes the following steps:
step 1001, monitoring radio frequency transmission power of an antenna in a working state in the at least one antenna.
Step 1002, determining whether the starting condition is met, that is, determining whether the monitored radio frequency transmission power is greater than a high power threshold Pht, if yes, triggering and continuously executing step 101, then sequentially executing step 102 and step 104, if not, not adjusting the radio frequency transmission power, and executing step 1001 again after waiting for a preset time interval. Wherein the preset time interval is a preset empirical value, such as 50 ms.
After step 104 is performed, the rf transmission power is monitored again by returning to step 1001.
Through the steps, the electromagnetic wave absorption adjusting method only detects the impedance of the antenna when the radio frequency transmitting power of the antenna is larger than the high-power threshold, but does not detect the impedance of the antenna when the radio frequency transmitting power of the antenna is smaller than or equal to the high-power threshold, so that the detection times of the impedance are reduced, the lower resource scheduling of the system is ensured, and the low power consumption of the system is ensured.
Further, in order to avoid that the radio frequency transmission power of the antenna swings around the high-power threshold Pht, which causes frequent triggering or closing of impedance detection, the electromagnetic wave absorption ratio adjustment method of this embodiment also presets a low-power threshold Plt, and the monitored radio frequency transmission power is smaller than the low-power threshold as a termination condition for stopping step 101. Wherein the low power threshold Plt is smaller than the high power threshold Pht, and the low power threshold Plt may be generally set to be Pht-3 (dB). Of course, the present invention is not limited to this, and the low power threshold Plt may be set to other values according to actual requirements.
The electromagnetic wave absorption adjustment method of the present embodiment may be further optimized as the flow shown in fig. 3, and specifically includes the following steps after step 104 is executed:
and 105, judging whether the termination condition is met, namely judging whether the monitored radio frequency transmission power is smaller than a small power threshold Plt, if so, stopping detecting the impedance of the antenna in the working state in the at least one antenna, then returning to the step 1001, and if not, returning to the step 101 to continuously detect the impedance of the antenna in the working state in the at least one antenna.
Fig. 4 shows a diagram of the high power threshold Pht and the low power threshold Plt. The curve in the figure is the radio frequency transmission power monitored over time, the step of detecting the impedance of the antenna in operation of said at least one antenna starting from a radio frequency transmission power greater than the high power threshold Pht and continuing until the radio frequency transmission power is less than the low power threshold Plt.
The embodiment avoids frequent switching of impedance detection and realizes smooth control of impedance detection through the combined action of the high-power threshold Pht and the low-power threshold Plt. If the rf front-end device can operate in multiple frequency bands, a high power threshold Pht and a low power threshold Plt need to be set for each operating frequency band.
Example 3
This example is a further explanation of the method for adjusting the electromagnetic wave absorption ratio according to the present invention, based on example 2.
The radio frequency front end device of this embodiment specifically includes an antenna, and the electromagnetic wave absorption ratio adjustment method further provides a pre-stored table, where the pre-stored table includes: the antenna comprises n preset UI scenes (n is more than or equal to 1), impedance of the antenna in a working state under each UI scene, and maximum radio frequency transmitting power corresponding to the UI scenes one by one. And the maximum radio frequency transmitting power in one-to-one correspondence with the UI scene is an empirical value obtained by actually measuring the radio frequency transmitting power of the antenna on the premise of meeting SAR indexes in the UI scene.
As shown in fig. 5, the method for adjusting the electromagnetic wave absorption ratio of the present embodiment specifically includes the following steps:
step 201, detecting whether the antenna is in a working state, if so, executing step 202, otherwise, executing step 201 again after waiting for a first time interval. Wherein the first time interval is a preset empirical value, such as 50 ms.
Step 202, monitoring the radio frequency transmission power of the antenna.
Step 203, judging whether the starting condition is met, namely judging whether the monitored radio frequency transmitting power is greater than a high-power threshold Pht, if so, triggering and continuously executing step 204, otherwise, not adjusting the radio frequency transmitting power, and executing step 201 again after waiting for a second time interval. Wherein the high-power threshold is less than or equal to a minimum value of maximum radio frequency transmission power of the antenna in all UI scenarios, and the second time interval is a preset empirical value, such as 50 ms.
And step 204, detecting the impedance of the antenna.
Step 205, querying the pre-stored table, and finding out the UI scene corresponding to the impedance of the antenna from the pre-stored table.
And step 206, finding out the maximum radio frequency emission power of the antenna according with SAR indexes from the pre-stored table according to the determined UI scene.
And step 207, reducing the radio frequency transmission power of the antenna to be lower than the corresponding maximum radio frequency transmission power.
In the embodiment, the mapping relation between the UI scene, the impedance of the antenna and the maximum radio frequency transmission power is stored by using the pre-stored table, so that the determination from the impedance of the antenna to the UI scene and then from the UI scene to the maximum radio frequency transmission power is realized, and the adjustment of the SAR for the random switching among various UI scenes can be possible in time.
Further, monitoring the radio frequency transmission power of the antenna in step 202 may be achieved by monitoring RGI (radio frequency Gain Index). This is because the radio frequency transmission power, which has a one-to-one correspondence with the RGI, needs to be calibrated by the power of the system. Namely, the system can obtain the expected radio frequency emission power by issuing the RGI command, and then the system can be realized by only monitoring the RGI when monitoring the radio frequency emission power.
Further, the impedance of the antenna in this embodiment may be specifically represented by the position of the impedance of the antenna on the Smith chart. The impedance area of the antenna in the working state under each UI scene is stored in the pre-stored table, and the impedance area is a set of positions of the actually measured impedance of the antenna on the Smith chart under the UI scene. Fig. 6 schematically shows an impedance region Ai (i e [1, n ]) of the antenna in n UI scenarios. Any point within the impedance region Ai corresponds to the i-th UI scenario. Each impedance area shown in the figure is circular, the corresponding area radius is Ri, the area radius of each impedance area may be the same or different, and the adjustment may be made according to different area sizes. By adjusting the size of the area radius, the sensitivity of the impedance of the antenna can be adjusted, namely, the smaller the area radius is, the higher the sensitivity is, and the larger the area radius is, the lower the sensitivity is; the setting of the specific area radius needs to be combined with actual antenna debugging, and in this embodiment, it is default that the area radius of each impedance area is equal to 3 dB.
In this embodiment, each impedance region should be distinguished to ensure one-to-one correspondence between the impedance and the UI scene. However, in the actual impedance region boundary, there may be a case where impedance regions corresponding to different UI scenes overlap or are less than a preset distance threshold apart, which results in that it is difficult to distinguish which UI scene corresponds to at present when the position of the antenna impedance falls between the overlapping region or two close regions. In order to avoid this, when the pre-stored table is established, if it is found that impedance regions corresponding to different UI scenes overlap or have a distance smaller than a preset distance threshold, the different UI scenes may be merged into one UI scene, and the impedance region corresponding to the merged UI scene covers the sum of the impedance regions corresponding to the different UI scenes.
Table 1 shows schematically a pre-stored table of the present embodiment for reference:
TABLE 1
Figure BDA0001486944380000121
Figure BDA0001486944380000131
The meaning represented by the above-described part of the exemplary UI scenario is briefly explained below:
the free space refers to the radio frequency front-end device or the radio frequency front-end device installed far away from the human body;
the left head is 15 degrees, namely the included angle between the head of the left side of the user and the radio frequency front end device or the radio frequency front end device is arranged;
the left head is tightly attached, namely the left head of the user is tightly attached to the radio frequency front end device or the radio frequency front end device is installed;
the top surface body means that the radio frequency front end device or the top surface provided with the radio frequency front end device is close to the human body.
Of course, the present invention is not limited to the UI scenario in table 1, and the technician may set the UI scenario and perform corresponding measurement according to the measurement or adjustment requirement.
On the basis of the pre-stored table, step 204 specifically includes: and detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart. Thereby realizing the detection of the antenna impedance.
Step 205 specifically includes: and searching the pre-stored table, determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area. Therefore, the current UI scene is found from the pre-stored table, and the subsequent radio frequency transmission power is adjusted.
Example 4
This example is a further explanation of the electromagnetic wave absorption ratio adjusting method of the present invention based on example 3.
The rf front-end device of the present embodiment also includes an antenna, and the method for adjusting the electromagnetic wave absorption ratio also provides a pre-stored table. The pre-stored table of this embodiment is substantially the same as the pre-stored table of embodiment 3, except that the pre-stored table of this embodiment further includes: and under preset n UI scenes, the radio frequency power back-off quantity of the antenna is not less than the minimum back-off quantity of the radio frequency power.
Wherein the minimum back-off Δ P of the RF power is P-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxAnd the maximum transmitting power is the maximum radio frequency transmitting power which is prestored in a prestored table and corresponds to the UI scene one by one and accords with the electromagnetic wave absorption ratio index when the antenna is in the working state under the UI scene.
Table 2 shows schematically a pre-stored table of the present embodiment for reference:
TABLE 2
Figure BDA0001486944380000141
In table 2, the radio frequency power back-off Δ P is the minimum radio frequency power back-off Δ P — Pmax。
On the basis of the pre-stored table of the present embodiment, as shown in fig. 7, the electromagnetic wave absorption ratio adjustment method of the present embodiment is different from the electromagnetic wave absorption ratio adjustment method of embodiment 3 in that step 206 and step 207 of embodiment 3 are replaced with:
and step 206', searching the pre-stored table, and reducing the radio frequency transmission power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene.
In this embodiment, the pre-stored table directly records the radio frequency power back-off under different UI scenarios, and after the radio frequency transmission power of the antenna is reduced according to the radio frequency power back-off recorded in the table, the radio frequency transmission power is naturally reduced below the maximum transmission power, which meets the SAR index.
In order to further accelerate the speed and accuracy of the whole SAR adjustment, the pre-stored table of this embodiment may be further optimized to include an execution code that needs to be invoked by the antenna to reduce the corresponding radio frequency power back-off in each UI scenario.
Table 3 gives, schematically, for reference, a further optimized pre-stored table:
TABLE 3
Figure BDA0001486944380000151
On the basis of the pre-stored table, step 206' is implemented by calling and executing the corresponding execution code of the antenna in the UI scene.
Example 5
This example is a further explanation of the electromagnetic wave absorption ratio adjusting method of the present invention based on example 1.
The radio frequency front-end device of the embodiment specifically comprises m antennas, wherein m is greater than or equal to 2, the electromagnetic wave absorption ratio adjusting method further provides a pre-stored table, and the pre-stored table comprises: the method comprises the following steps of presetting n UI scenes (n is more than or equal to 1), an impedance area when each antenna in the m antennas is in a working state under each UI scene, and the radio frequency power back-off quantity of each antenna in the m antennas under each UI scene.
Table 4 shows schematically a pre-stored table of the present embodiment for reference:
TABLE 4
Figure BDA0001486944380000161
If a plurality of antennas are in a working state at the same time, in order to avoid exceeding SAR, Δ s is further introduced to compensate the radio frequency power back-off.
Specifically, when the number of antennas in the operating state is m and m > 1, the compensated rf power back-off is equal to the original Δ P- Δ s, Δ s is equal to-5 × log (1/. i.e., as shown in table 5:
TABLE 5
Figure BDA0001486944380000171
As shown in fig. 8, the method for adjusting the electromagnetic wave absorption ratio of the present embodiment specifically includes the following steps:
and 301, detecting the number of the antennas in the working state in the m antennas.
Step 302, determining whether the number is greater than 1, if so, executing step 303, and if not, executing step 304.
Step 303, performing radio frequency power back-off for each antenna in the working state one by one. Specifically, radio frequency power backoff may be performed on each antenna in a working state according to a pre-stored table shown in table 5, and the specific backoff process may be implemented by referring to the adjustment method in embodiment 3 or 4, which is not described herein again.
And step 304, performing radio frequency transmission power backoff on the only antenna in the working state. In this case, it can be regarded that the radio frequency front end device only includes one antenna, and specifically, radio frequency transmission power backoff may be performed on the only antenna in the working state according to the pre-stored table in table 4, and the specific backoff process may be implemented with reference to the adjustment method in embodiment 3 or 4, which is not described herein again.
Example 6
An electromagnetic wave absorption ratio adjustment system of a radio frequency front end device, the radio frequency front end device including at least one antenna, as shown in fig. 9, the electromagnetic wave absorption ratio adjustment system comprising:
an impedance detection unit 401, configured to detect an impedance of an antenna in an operating state in the at least one antenna;
the control processing unit 402 is configured to determine a UI scene where the radio frequency front-end device is located according to the detected impedance, and acquire maximum radio frequency transmission power of an antenna in a working state meeting an electromagnetic wave absorption ratio index in the UI scene;
a power adjusting unit 403, configured to reduce the radio frequency transmission power of the antenna in the working state to be lower than the corresponding maximum radio frequency transmission power.
The electromagnetic wave absorption ratio adjusting system of the embodiment can reduce the radio frequency emission power of the antenna according to the current UI scene, so as to reduce the SAR, thereby conforming to the SAR index.
Example 7
This example is a further explanation of the electromagnetic wave absorption ratio adjustment system of the present invention based on example 6.
In order to avoid the repeated adjustment of the rf transmitting power and occupy too much system resources, as shown in fig. 10, the system for adjusting the absorption ratio of electromagnetic waves of this embodiment further includes a power monitoring unit 404.
The power monitoring unit 404 is configured to monitor radio frequency transmission power of an antenna in an operating state in the at least one antenna, and when an initial condition is met, trigger the impedance detecting unit 401 to continuously detect impedance of the antenna in the operating state in the at least one antenna;
the starting condition is that the monitored radio frequency transmitting power is larger than a preset high-power threshold, wherein the high-power threshold is smaller than or equal to the minimum value of the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under all UI scenes.
Further, in order to avoid that the radio frequency transmission power of the antenna swings around the high-power threshold Pht, which causes frequent triggering or turning off of impedance detection, the power monitoring unit is further configured to control the impedance detection unit 401 to stop detecting the impedance of the antenna in the working state in the at least one antenna when a termination condition is met;
the termination condition is that the monitored radio frequency transmission power is smaller than a preset small power threshold, wherein the small power threshold is smaller than the high power threshold.
Example 8
This example is a further explanation of the electromagnetic wave absorption ratio adjusting system of the present invention based on example 7.
As shown in fig. 11, the electromagnetic wave absorption ratio adjustment system of the present embodiment further includes a pre-stored table storage unit 405.
The pre-stored table storage unit 405 is configured to store a pre-stored table, where the pre-stored table includes n preset UI scenes (n is greater than or equal to 1), impedance of each antenna in the at least one antenna in a working state in each UI scene, and maximum radio frequency transmission power corresponding to the UI scenes one to one.
The determining, by the control processing unit 402, the UI scene where the radio frequency front-end device is located according to the detected impedance specifically includes:
and searching a pre-stored table, and finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table.
The acquiring, by the control processing unit 402, the maximum radio frequency transmission power of the antenna in the working state in the UI scene, which meets the electromagnetic wave absorption ratio index, specifically includes:
and finding out the maximum radio frequency transmitting power of the antenna in the working state according with the electromagnetic wave absorption ratio index from the pre-stored table according to the determined UI scene.
Further, the power monitoring unit 404 may monitor the radio frequency transmission power of each antenna in the at least one antenna in an active state by monitoring an RGI (radio frequency Gain Index). The radio frequency transmission power has a one-to-one correspondence with the RGI.
Further, the impedance of the antenna in this embodiment may be specifically represented by the position of the impedance of the antenna on the Smith chart. The pre-stored table stores an impedance area of each antenna in the at least one antenna in a working state under each UI scene, and the impedance area is a set of positions of actually measured impedance of the antenna on the Smith chart under the UI scene.
In the pre-stored table, if the impedance areas corresponding to different UI scenes overlap or the distance between the impedance areas is smaller than a preset distance threshold, combining the different UI scenes into one UI scene, wherein the impedance area corresponding to the combined UI scene covers the sum of the impedance areas corresponding to the different UI scenes.
The detecting unit 401 detects an impedance of an antenna in a working state in the at least one antenna, and specifically includes: detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart;
the control processing unit 402 finds out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table, and specifically includes: and determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area.
Example 9
This example is a further explanation of the electromagnetic wave absorption ratio adjustment system of the present invention based on example 8.
The pre-stored table of this embodiment is substantially the same as the pre-stored table of embodiment 8, except that the pre-stored table of this embodiment further includes: the radio frequency power back-off quantity of each antenna in the at least one antenna under at least one preset UI scene is not less than the minimum radio frequency power back-off quantity;
wherein the minimum back-off Δ P of the RF power is P-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxAnd the maximum transmitting power is the maximum radio frequency transmitting power which is prestored in a prestored table and corresponds to the UI scene one by one and accords with the electromagnetic wave absorption ratio index when the antenna is in the working state under the UI scene.
When the number of the antennas in the working state is m and m is more than 1, the minimum back-off amount of the radio frequency power is further optimized as follows: Δ P ═ P-Pmax-Δs，Δs＝-5*log(1/。
The control processing unit 402 is further configured to obtain a radio frequency power back-off of the antenna in the working state in the UI scene by searching the pre-stored table;
the power adjustment unit 403 is further configured to reduce the radio frequency transmission power of the antenna in the working state by the obtained radio frequency power back-off amount.
In order to further accelerate the speed and accuracy of the whole SAR adjustment, the pre-stored table further comprises an execution code which needs to be called when each antenna in the at least one antenna reduces the corresponding radio frequency power back-off under at least one preset UI scene;
the power adjustment unit 403 reduces the rf transmit power of the antenna in the working state by the corresponding rf power back-off in the UI scenario by calling and executing the corresponding execution code.
Example 10
A radio frequency front end device, comprising at least one antenna and the electromagnetic wave absorption ratio adjustment system according to any one of embodiments 6 to 9.
When the radio frequency front-end device or a terminal provided with the radio frequency front-end device is used, the impedance of the antenna changes due to different surrounding environments, and therefore the performance of the antenna changes according to the change of an actual use scene. The electromagnetic wave absorption ratio adjusting system determines the current UI scene by using the corresponding relation between the impedance of the antenna and the use scene, thereby realizing the adjustment of the radio frequency transmitting power.
The following describes a specific principle of the present embodiment for detecting the impedance of the antenna with reference to fig. 12:
fig. 12 shows an antenna ANT, a radio frequency integrated circuit RFIC, a power amplifier PA, a duplexer DPX, a bidirectional Coupler with a switching function, and a Balun. The multiband transmitting band TX and the multiband receiving band RX of the RFIC are characterized in that Incident waves (Incident Wave) and transmitted waves (reflected Wave) at an antenna end are sampled and detected through a bidirectional Coupler, the Incident waves and the transmitted waves are converted into differential signals through a Balun and input to the RFIC, and the differential FB _ I and FB _ Q can be subjected to Binary Phase Shift Keying (BPSK) modulation to realize sampling detection of the amplitude and the Phase of the sampled signals. The impedance change of the antenna can be tracked in real time according to the sampling feedback of the Coupler.
Fig. 13 is a schematic diagram of the bidirectional Coupler. The Coupler is provided with a DPDT (double-pole double-throw) switch, and is used for sampling incident waves and reflected waves at an antenna end based on a bidirectionally detected Coupler, calculating S11, S12, S21 and S22 through an S parameter network, and acquiring the impedance of the antenna according to the S parameter network.
Example 11
A terminal comprising the radio frequency front end apparatus of embodiment 10. The terminal can be a mobile phone, a tablet computer and the like.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.

Claims (18)

1. An electromagnetic wave absorption ratio adjusting method of a radio frequency front end device, the radio frequency front end device including at least one antenna, the electromagnetic wave absorption ratio adjusting method comprising:
detecting an impedance of an active antenna of the at least one antenna, comprising: detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart;
searching a pre-stored table, and finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table, wherein the UI scene comprises the following steps: determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area;
the pre-stored table comprises impedance areas when each antenna in the at least one antenna is in a working state in at least one preset UI scene, and the impedance areas are a set of positions of actually measured impedance of the antenna on a Smith chart in the UI scene;
acquiring the maximum radio frequency transmitting power of the antenna in the working state in the UI scene, wherein the maximum radio frequency transmitting power accords with the electromagnetic wave absorption ratio index;
and reducing the radio frequency transmission power of the antenna in the working state below the corresponding maximum radio frequency transmission power.
2. The electromagnetic wave absorption ratio adjustment method according to claim 1, wherein the pre-stored table further includes: maximum radio frequency transmitting power corresponding to the UI scenes one by one;
acquiring the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index under the UI scene, wherein the maximum radio frequency transmitting power comprises the following steps:
and finding out the maximum radio frequency transmitting power of the antenna in the working state according with the electromagnetic wave absorption ratio index from the pre-stored table according to the determined UI scene.
3. The method for adjusting an absorption ratio of electromagnetic waves according to claim 1, wherein the pre-stored table further includes a radio frequency power back-off amount of each antenna of the at least one antenna in at least one preset UI scenario, the radio frequency power back-off amount being not less than a radio frequency power minimum back-off amount;
the minimum back-off Δ P of the radio frequency power is P-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxThe maximum radio frequency transmitting power is the maximum radio frequency transmitting power which is in accordance with the electromagnetic wave absorption ratio index when the antenna is in a working state under the UI scene, and the maximum transmitting power is the maximum radio frequency transmitting power which is pre-stored in a pre-stored table and corresponds to the UI scene one by one;
the method for adjusting the electromagnetic wave absorption ratio further comprises the steps of obtaining the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index in the UI scene and reducing the actual radio frequency transmitting power of the antenna in the working state to be below the corresponding maximum radio frequency transmitting power, and replacing the steps with the steps of:
and searching the pre-stored table, and reducing the radio frequency transmitting power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene.
4. The electromagnetic wave absorption ratio adjustment method according to claim 3, wherein m is the number of antennas detected to be in an operating state, and m is the number of antennas detected to be in an operating state>1, the minimum back-off Δ P of the radio frequency power is P-Pmax-Δs，Δs＝-5*log(1/m)。
5. The method for adjusting an absorption ratio of electromagnetic waves according to claim 3, wherein the pre-stored table further includes an execution code to be called for reducing a corresponding radio frequency power back-off for each of the at least one antenna in at least one preset UI scenario;
and reducing the radio frequency transmission power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene, and calling and executing the corresponding execution code.
6. The electromagnetic wave absorption ratio adjustment method according to claim 1, characterized by further comprising:
monitoring the radio frequency transmission power of the antenna in the working state in the at least one antenna, and triggering and continuously detecting the impedance of the antenna in the working state in the at least one antenna when the starting condition is met;
the starting condition is that the monitored radio frequency transmitting power is larger than a preset high-power threshold, wherein the high-power threshold is smaller than or equal to the minimum value of the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under all UI scenes.
7. The electromagnetic wave absorption ratio adjustment method according to claim 6, wherein the step of detecting the impedance of the antenna in an operating state of the at least one antenna is stopped when a termination condition is satisfied;
the termination condition is that the monitored radio frequency transmission power is smaller than a preset small power threshold, wherein the small power threshold is smaller than the high power threshold.
8. The method for adjusting an electromagnetic wave absorption ratio according to claim 1, wherein in the pre-stored table, if there is an overlap between impedance regions corresponding to different UI scenes or the distance between the impedance regions is smaller than a preset distance threshold, the different UI scenes are merged into one UI scene, and the impedance region corresponding to the merged UI scene covers the sum of the impedance regions corresponding to the different UI scenes.
9. An electromagnetic wave absorption ratio adjustment system of a radio frequency front end device, the radio frequency front end device including at least one antenna, the electromagnetic wave absorption ratio adjustment system comprising:
the impedance detection unit is used for detecting the impedance of the antenna in a working state in the at least one antenna, and comprises: detecting the position of the impedance of the antenna in the working state in the at least one antenna on the Smith chart;
the control processing unit is used for searching a pre-stored table and finding out a UI scene corresponding to the impedance of the antenna in the working state from the pre-stored table, and comprises the following steps: determining an impedance area where the detected position falls according to the pre-stored table, and acquiring a UI scene corresponding to the falling impedance area; the pre-stored table comprises impedance areas when each antenna in the at least one antenna is in a working state in at least one preset UI scene, and the impedance areas are a set of positions of actually measured impedance of the antenna on a Smith chart in the UI scene;
the control processing unit is also used for acquiring the maximum radio frequency transmitting power of the antenna in the working state in the UI scene, wherein the antenna accords with the electromagnetic wave absorption ratio index;
and the power adjusting unit is used for reducing the radio frequency transmitting power of the antenna in the working state to be lower than the corresponding maximum radio frequency transmitting power.
10. The electromagnetic wave absorption ratio adjustment system according to claim 9, wherein the prestored table further includes: maximum radio frequency transmitting power corresponding to the UI scenes one by one;
acquiring the maximum radio frequency transmitting power of the antenna in the working state meeting the electromagnetic wave absorption ratio index under the UI scene, wherein the maximum radio frequency transmitting power comprises the following steps:
and finding out the maximum radio frequency transmitting power of the antenna in the working state according with the electromagnetic wave absorption ratio index from the pre-stored table according to the determined UI scene.
11. The electromagnetic wave absorption ratio adjustment system according to claim 9, wherein the pre-stored table further includes a radio frequency power back-off amount for each antenna of the at least one antenna in at least one preset UI scenario, the radio frequency power back-off amount being not less than a radio frequency power minimum back-off amount;
the minimum back-off Δ P of the radio frequency power is equal toP-PmaxWherein P is the actual radio frequency emission power of the antenna in the working state under the UI scene, and PmaxThe maximum radio frequency transmitting power is the maximum radio frequency transmitting power which is in accordance with the electromagnetic wave absorption ratio index when the antenna is in a working state under the UI scene, and the maximum transmitting power is the maximum radio frequency transmitting power which is pre-stored in a pre-stored table and corresponds to the UI scene one by one;
the control processing unit is further configured to obtain a radio frequency power back-off quantity of the antenna in a working state in the UI scene by searching the pre-stored table;
the power adjusting unit is further configured to reduce the radio frequency transmission power of the antenna in the working state by the obtained radio frequency power back-off amount.
12. The electromagnetic wave absorption ratio adjustment system according to claim 11, wherein the control processing unit detects that the number of antennas in operation is m and m is>1, the minimum back-off Δ P of the radio frequency power is P-Pmax-Δs，Δs＝-5*log(1/m)。
13. The electromagnetic wave absorption ratio adjustment system according to claim 11, wherein the pre-stored table further includes an execution code to be invoked for reducing a corresponding radio frequency power back-off for each of the at least one antenna in at least one preset UI scenario;
and the power adjusting unit reduces the radio frequency transmitting power of the antenna in the working state by the corresponding radio frequency power backspacing under the UI scene by calling and executing the corresponding execution code.
14. The electromagnetic wave absorption ratio adjustment system according to claim 9, further comprising a power monitoring unit;
the power monitoring unit is used for monitoring the radio frequency transmission power of an antenna in a working state in the at least one antenna, and triggering the impedance detection unit to continuously detect the impedance of the antenna in the working state in the at least one antenna when an initial condition is met;
the starting condition is that the monitored radio frequency transmitting power is larger than a preset high-power threshold, wherein the high-power threshold is smaller than or equal to the minimum value of the maximum radio frequency transmitting power which accords with the electromagnetic wave absorption ratio index when the antenna is in a working state under all UI scenes.
15. The electromagnetic wave absorption ratio adjustment system according to claim 14, wherein the power monitoring unit is further configured to control the impedance detection unit to stop detecting the impedance of the antenna in the operating state among the at least one antenna when a termination condition is satisfied;
the termination condition is that the monitored radio frequency transmission power is smaller than a preset small power threshold, wherein the small power threshold is smaller than the high power threshold.
16. The electromagnetic wave absorption ratio adjustment system according to claim 9, wherein in the pre-stored table, if there is overlap between impedance regions corresponding to different UI scenes or the distance between the impedance regions is smaller than a preset distance threshold, the different UI scenes are merged into one UI scene, and the impedance region corresponding to the merged UI scene covers the sum of the impedance regions corresponding to the different UI scenes.
17. A radio frequency front end device, comprising at least one antenna and the electromagnetic wave absorption ratio adjustment system according to any one of claims 9 to 16.
18. A terminal, characterized in that it comprises a radio frequency front end device according to claim 17.
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