TWI795802B - Transmission power reduction - Google Patents

Abstract

In one example in accordance with the present disclosure, an electronic device is described. An example electronic device includes a first antenna to transmit a radio frequency (RF) signal and a second antenna to receive the RF signal. The example electronic device also includes a controller. The example controller 1) determines an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal and 2) reduces a transmission power of the first antenna based on the antenna-to isolation being outside of a threshold range.

Description

Transmit Power Reduction Technology

This disclosure relates to transmit power reduction techniques.

Electronic devices include wireless antennas for transmitting information between electronic devices that are not physically connected to each other. The antenna communicates wirelessly with other antennas through a wireless network. Different wireless networks include different communication protocols, and antennas that are part of a wireless network communicate according to these protocols. One example of a wireless network is a Wi-Fi network. Another example of a wireless network is a Long Term Evolution (LTE) network. An electronic device includes a corresponding antenna for each wireless network through which the electronic device communicates. For example, an electronic device with a Wi-Fi antenna can transmit and receive data via a Wi-Fi network. If the electronic device includes an LTE antenna, it can also communicate via the LTE network.

According to an embodiment of the present invention, an electronic device is specially provided, which includes: a first antenna for transmitting a radio frequency (RF) signal; a second antenna for receiving the RF signal; and a controller that: determines an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal; and reduces the first antenna-to-antenna isolation based on the antenna-to-antenna isolation being outside a threshold range One of the antennas transmits power.

100: Electronic device

102-1, 102-2: Antenna

104: Controller

206: user

208: Database

310-1, 310-2: radio

312-1, 312-2: Wireless Network Chipset

400: method

401~406: steps

514: Non-transitory machine-readable storage medium

516~522: instruction

The accompanying drawings illustrate various examples of the principles described herein and are a part of this specification. The examples shown are for illustrative purposes only and do not limit the scope of the claims.

FIG. 1 is a block diagram of an electronic device for reducing antenna transmission power according to an example.

FIG. 2 shows an electronic device for reducing antenna transmission power according to an example.

FIG. 3 is a block diagram of an electronic device for reducing antenna transmission power according to an example.

FIG. 4 is a flowchart of a method for reducing antenna transmit power, according to an example.

FIG. 5 illustrates a non-transitory machine-readable storage medium for reducing antenna transmit power, according to an example.

Throughout the drawings, like reference numerals designate similar, but not necessarily identical, elements. The drawings are not necessarily to scale and the dimensions of some of the components may have been exaggerated to more clearly illustrate the examples shown. In addition, these drawings provide examples and/or implementations consistent with this description; however, this description is not limited to the examples and/or implementations provided in these drawings.

Electronic devices include any number of antennas to facilitate wireless communications. For example, an electronic device may include a Wi-Fi antenna that allows the electronic device to transmit and receive information over a Wi-Fi network. As another example, the electronic device may include an LTE antenna that allows the electronic device to transmit and receive information over an LTE network. Each of these different networks incorporates a different protocol. Since different wireless networks have different operating parameters and communication protocols, each can be specially adapted to a specific environment. Thus, an electronic device with many different antennas can wirelessly transmit and receive information in a number of different situations.

Although wireless communication has undoubtedly shaped the way societies communicate with each other, some properties still limit its fuller implementation. For example, objects in a user's environment can affect radio frequency (RF) signals through which information is transmitted.

In some examples, RF waves can be absorbed by the human body. The absorption of RF waves by the human body can cause personal injury. Therefore, some entities, such as the government, by imposing A limit regulates the communication devices so as to limit the amount of RF energy absorbed by a user. This limit may be referred to as a specific absorption rate (SAR) threshold. The effect of RF waves on the human body can be reduced by reducing the RF transmission power. Human bodies and other objects can also reflect RF signals. That is, a human body close to one of the antennas can cause the RF signal to be higher or lower due to the body blocking or reflecting the RF signal.

Accordingly, this specification describes electronic devices and non-transitory machine-readable storage media that reduce RF transmission power when a human being is detected nearby. More specifically, a human being in the vicinity of a transmit antenna can affect the rate at which RF signal power is dissipated between a transmit antenna and a receive antenna. Antenna-to-antenna isolation can be determined to determine blocking of RF emissions. Antenna-to-antenna isolation outside a threshold range indicates that something such as a human body is blocking RF signals. The transmit power can then be varied to reduce the effect of the RF waves on the user. In one example, the specification describes electronic devices that reduce antenna transmit power to meet a specific SAR threshold.

Specifically, this specification implements two antennas, which may or may not be on the same wireless network. One of the antennas generates a radio frequency signal. When the first antenna is transmitting RF signals, a controller uses a second antenna to receive RF signals transmitted from the first antenna. The controller monitors the power of both the transmit and receive antennas at the location to determine if the antenna-to-antenna isolation has changed by more than a threshold level. The controller determines an antenna-to-antenna isolation value by subtracting the received signal power from the signal strength of the transmitted signal. The controller then adjusts transmit power based on the antenna isolation value. In one specific example, the change may indicate that a human body may be close enough to the antenna that the transmit power of the antenna should be reduced to reduce the SAR level.

Specifically, this specification describes an electronic device. The electronic device includes a first antenna for transmitting a radio frequency (RF) signal and a second antenna for receiving the RF signal. The electronic device also includes a controller. The controller 1) determines an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal, and 2) reduces a transmit power of a first antenna based on the antenna-to-antenna isolation being outside a threshold range .

In another example, an electronic device includes a first radio having a first antenna for transmitting a radio frequency (RF) signal. A second radio has a radio for receiving RF signals A second antenna. In this example, the first radio and the second radio operate in different frequency bands. The electronic device also includes a controller for 1) determining an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal, and 2) responding to the antenna-to-antenna isolation being at a threshold Out of range, reduce the transmit power of one of the first antennas.

The specification also describes a non-transitory machine-readable storage medium comprising instructions that, when executed by a processor of an electronic device, cause the processor to determine a day based on a specific absorption rate (SAR) threshold Line-to-antenna isolation threshold. The machine-readable storage medium also includes instructions that, when executed by the processor, cause the processor to transmit a radio frequency (RF) signal from a first antenna of an electronic device, and based on a transmitted RF signal and Antenna-to-antenna isolation is determined as a difference between the RF signals received by a second antenna of the electronic device. The machine-readable storage medium also includes instructions that, when executed by the processor, cause the processor to cause one of the first antennas to transmit in response to a determination that the antenna-to-antenna isolation is outside a threshold range Reduced power.

The term "controller" as used in this specification and the accompanying claims may be a processor, an application specific integrated circuit (ASIC), a semiconductor-based microprocessor, a central processing unit (CPU) , and Field Programmable Gate Array (FPGA), and/or other hardware devices.

Memory may include a computer-readable storage medium that may contain or store computer-usable program code for use by or in conjunction with an instruction execution system, apparatus, or device. The memory can take the form of many types of memory, including volatile and non-volatile memory. Memory may include, for example, random access memory (RAM), read only memory (ROM), optical memory disk, and magnetic disk, among other media. The executable code, when executed by the corresponding component, causes the component to perform at least the functions described herein.

Furthermore, the term "antenna-to-antenna isolation" as used in this specification and the accompanying claims means a difference between a transmitted signal strength and a received signal strength. For example, antenna-to-antenna isolation can mean that the percentage of the transmitted signal received can be defined as antenna-to-antenna isolation. Antenna-to-antenna isolation values may have a unit of measurement in decibels (dB).

Referring now to the drawings, FIG. 1 is a block diagram of an electronic device 100 for reducing the transmission power of an antenna 102 according to an example. As mentioned above, the electronic device 100 controls the RF transmission power. Specifically, this is accomplished by detecting antenna-to-antenna isolation. Detecting antenna-to-antenna isolation can be used to determine whether a human is approaching the electronic device 100 . That is, the human body has low impedance compared to air, so that the human body close to the electronic device 100 can change the antenna-to-antenna isolation. In this case, the RF transmit power can be reduced to ensure that the electronic device 100 does not transmit too much RF energy when there is a human being nearby. That is, the RF transmit power can be reduced to meet a specific absorption rate (SAR) threshold that is considered safe for humans.

The electronic device 100 can be of various types including a desktop computer, a laptop computer, a tablet computer, a smartphone, or any other electronic device 100 or any other electronic device 100 including the wireless antenna 102 .

The electronic device 100 includes a first antenna 102-1 for transmitting an RF signal and a second antenna 102-2 for receiving an RF signal. As mentioned above, through these antennas 102 , the electronic device 100 can transmit and receive information wirelessly. In the electronic device 100, the antennas 102 can be used to determine an antenna-to-antenna isolation whose antenna-to-antenna isolation value can be used to 1) determine a material that blocks an RF signal, and 2) determine whether to reduce RF transmit power. The antenna 102 can belong to different wireless networks. Examples of wireless networks include a Wi-Fi network and LTE networks using wireless methods.

The electronic device 100 also includes a controller 104 . As mentioned above, "controller" refers to various hardware components, including a processor and memory. Processors include circuitry to retrieve executable code from memory and execute the executable code. The controller 104 is to determine an antenna-to-antenna isolation based on a difference between a transmitted RF signal and a received RF signal. That is, in any given situation, there may be a difference between a transmitted RF signal and a received RF signal. The percentage of transmitted signal received can be defined as antenna-to-antenna isolation. In other words, antenna-to-antenna isolation means a difference between a transmitted signal power and a received signal power. The power of a signal can be measured in decibels per milliwatt (dBm) bits, and a difference between a transmitted and received signal may have a unit of measurement in decibels (dB). A specific numerical example is now provided. In this example, the first antenna 102-1 may transmit at an intensity of 1000 milliwatts (mW), which may also be described as 30 dBm. The second antenna 102-2 can receive signals at one strength of 100 mW or 20 dBm. Therefore, the antenna-to-antenna isolation for this configuration may be 10 dB.

The antenna-to-antenna isolation between the two antennas 102 on the electronic device 100 may vary to a certain extent throughout use. That is, for a desired antenna-to-antenna isolation of X, a tolerance variation may be ±Y such that an acceptable antenna-to-antenna isolation threshold range is X±Y. That is, network traffic is adapted by measuring a threshold range of measured antenna-to-antenna isolation values. A measured antenna-to-antenna isolation outside this range can indicate that a material or object is blocking the RF transmit path. If the measured antenna-to-antenna isolation differs sufficiently from the acceptable range, it may indicate that the transmit power should be reduced, for example, to prevent excessive absorption of RF energy by a nearby human.

Therefore, when the electronic device 100 is connected to an access point or a base station, the first antenna 102-1 is transmitting signals. Controller 104 monitors transmit power. The controller 104 monitors the received power at the second antenna 102-2. The controller 104 may then subtract the received power from the transmitted power to obtain an antenna-to-antenna isolation. The measurement of received signal power may be continuous or may be periodic. For example, the controller 104 may sample the RF received signal strength every two seconds.

When the environment is stable, the received power should be within the range of X±Y. In these cases, the first antenna 102-1 maintains a full transmit power. In contrast, when the antenna-to-antenna isolation is outside the threshold range, the controller 104 may reduce the transmit power of one of the first antennas 102-1.

In other words, the controller 104 determines whether the antenna-to-antenna isolation is outside a threshold range X±Y, and reduces the transmit power of the first antenna 102-1 when the antenna-to-antenna isolation is outside the range.

In one example, the threshold range is based on a specific absorption rate (SAR) threshold. That is, the SAR threshold may be a value that indicates a safe amount of RF energy that a human can absorb. That is, the upper limit of antenna-to-antenna isolation can be mapped to a SAR threshold beyond which there is a risk of injury to a human. Harmful effect. Therefore, any measured antenna-to-antenna isolation above the antenna-to-antenna isolation threshold indicates a SAR level above the SAR threshold.

The controller 104 also reduces a transmit power of the first antenna based on the antenna-to-antenna isolation being outside a threshold range. As mentioned above, an antenna-to-antenna isolation outside a threshold range may indicate that a human user is close enough to the electronic device 100 to be exposed to RF energy of the electronic device 100 .

Going back to the example where the antenna-to-antenna isolation threshold represents a SAR threshold, when the measured antenna-to-antenna isolation value is greater than the antenna-to-antenna isolation threshold, the transmit power of the first antenna 102-1 is reduced so that the SAR level is lower than the SAR threshold , which is safe for users.

In some examples, the controller 104 reduces the transmit power of the first antenna 102-1 based on the wireless network to which the first antenna 102-1 belongs. As a specific example, the antenna-to-antenna isolation threshold may indicate that a 15d Bm threshold received power level is acceptable. Therefore, if the controller 104 measures a received signal power of 20 dBm, the controller 104 may reduce the transmit power of the first antenna 102-1 by 5 dB to align with the antenna-to-antenna isolation threshold. However, for a different wireless network, such as a 4G or 5G cellular network, a received signal power may be 24dBm. Therefore, the controller 104 may reduce the power of the first antenna 102-1 by 9 dB to meet the antenna-to-antenna isolation threshold.

In some examples, the controller 104 determines a material type that blocks RF signals based on a degree to which antenna-to-antenna isolation is outside a threshold range. For example, in one test, an antenna-to-antenna isolation was measured across different frequency ranges and with different materials adjacent to the antenna 102 . Table 1 below presents the results of this test.

As shown in Table 1, different materials have different effects on signal attenuation. Therefore, based on the antenna For the antenna isolation value, the controller 104 may determine a type of material that blocks RF signals. Taking a specific example of a 5150MHz spectrum, when the measured antenna-to-antenna isolation value is between -24.9dB and -28.4dB, the controller 104 can determine that a human is within a threshold distance in front of the electronic device 100 .

Therefore, the specification illustrates the electronic device 100 that reduces the transmit power of the antenna 102 when the antenna-to-antenna isolation is outside a threshold range. Rather than reducing transmit power permanently to comply with a SAR threshold or when the electronic device 100 is in a specific mode such as a tablet mode, the electronic device 100 is activated when permitted, i.e. when a human is not near the electronic device 100 , allowing full transmit power and reducing transmit power when there is a user nearby.

FIG. 2 shows an electronic device 100 for reducing the transmission power of the antenna 102 according to an example. As mentioned above, an electronic device 100 such as a laptop computer may have any number of antennas 102 to allow wireless communication with other electronic devices 100 . Antenna-to-antenna isolation can be used to determine if an object, such as a user 206, is blocking RF signals. Blocking of RF signals can affect antenna performance. Antenna-to-antenna isolation can also identify if the user 206 is absorbing RF energy, which absorption could cause harm to the user 206 .

Absorption of RF energy can be reduced by reducing the transmit power of the first, and transmit antennas 102-1 until it reaches a safety level, which can be defined as an antenna-to-antenna isolation threshold below a recommended value.

Figure 2 also shows the controller 104 and a database 208, which assist in determining antenna-to-antenna isolation and reducing the transmit power of the first antenna 102-1. The controller 104 and the database 208 are shown in dashed lines to indicate their locations within the electronic device 100 .

As described above, the controller 104 may determine which material is blocking RF signals based on the antenna-to-antenna isolation value. Accordingly, the electronic device 100 may include a database 208 for mapping antenna-to-antenna isolation values to materials that may be blocking RF signals. For example, database 208 may include a look-up table, such as table (1), for identifying, for a frequency band of the transmitted signal, what material a particular measured antenna-to-antenna isolation value refers to.

As a first example, a measured antenna-to-antenna isolation value may be -35 dB when used in a 5825 MHz regime, indicating that a human body is blocking RF signals. In contrast, a measured antenna-to-antenna isolation value of -18dB may indicate that a metallic material, or metallic object, is blocking RF signals.

A specific example is now provided where antenna 102 is a wireless area network (WLAN) antenna with a transmit signal power of 20 dBm (100 milliwatts) for a 5-6 gigahertz (GHz) channel. In this example, the antenna-to-antenna isolation threshold may correspond to a SAR threshold of 1.6 milliwatts per gram (mW/g). In this example, the controller 104 determines that an antenna-to-antenna isolation of the electronic device 100 is -25.4 dB. From the perspective of antenna-to-antenna isolation, it is determined that the SAR of the electronic device 100 and the antenna power setting is 1.75 mW/g, which is greater than the SAR threshold.

Therefore, the controller 104 can reduce the transmit power of the first antenna 102-1, and can test the antenna-to-antenna isolation again. In this example, the controller 104 may reduce the transmit power of the first antenna to 18.5 dBm, which may map to a SAR level of 1.25 mW/g, and thus meet the SAR threshold. The controller 104 may then re-evaluate the antenna-to-antenna isolation to verify that it has a value within the threshold range. Note that this particular example provides a mapping between a maximum transmit power and SAR level. This value may depend on various characteristics including the electronic device 100 . Therefore, each electronic device can be associated with a mapping between the antenna-to-antenna isolation value, the transmit power value, and the SAR threshold.

In some examples, the controller 104 reduces the transmit power of the first antenna 102-1 based on the extent to which antenna-to-antenna isolation is outside a threshold range. Accordingly, the database 208 may map the antenna-to-antenna isolation value to a reduction in transmit power. For example, if the antenna-to-antenna isolation value is measured as -28.4 dB, the controller 104 may rely on entries in the database 208 to reduce the transmit power by a first amount. In contrast, if the antenna-to-antenna isolation value is measured as -24.9 dB, then the controller 104 may again rely on entries in the database 208 to reduce the transmit power by a second amount that is comparable to the first amount smaller.

In another example, the controller 104 reduces the transmission power of the first antenna 102-1 by a setting Quantify, and test the isolate again to see if it is still outside the threshold. That is, the controller 104 can repeatedly determine an antenna-to-antenna isolation, and reduce the transmit power incrementally until the antenna-to-antenna isolation is within the threshold range.

FIG. 3 is a block diagram of an electronic device 102 for reducing the transmission power of the antenna 102 according to an example. In the example shown in FIG. 3 , the electronic device 100 includes a first antenna 102-1 of a first radio 310-1, and a second antenna 102-2 of a second radio 310-2. That is to say, the first radio 310-1 and the second radio 310-2 may belong to different wireless networks.

That is, in some examples, the electronic device 100 has multiple radios 310 with overlapping frequency signals. In this example, a first antenna 102-1 of the first radio 310-1 may be used for transmission and a second radio 310-2 may be used for capturing radio signals through the second antenna 102-2. As a specific example, both an LTE and Wi-Fi antenna can operate in the 5GHz frequency range. In this example, the first antenna 102-1 may be part of a Wi-Fi radio to transmit signals, and the second antenna 102-2 may be part of an LTE radio to receive signals. Similar to the above, the controller 104 may determine the antenna-to-antenna isolation between the two antennas 102-1, 102-2 to determine whether to trigger a transmit power reduction and determine a transmit power reduction amount. Using antennas 102 from different radios 310 may be based on the sensitivity of the radios 310 to power fluctuations. For example, the second radio 310-2 may be more sensitive to power variations, so antenna-to-antenna isolation measurements may be more accurate and/or reliable.

In this example, the controller 104 receives information associated with the power of the transmitted RF signal from a first wireless network chipset 312-1, and from a second wireless network chipset 312-2. Information related to RF signal power. The controller 104 can communicate directly with the antenna 102 when the transmitted and received RF signals are on the same radio, or belong to the same wireless network as shown in FIG. 1 . However, when the transmitted and received RF signals are from different radios 310, or belong to different wireless networks, the controller 104 may rely on the intermediate chipset 312 to gather information about the signal power. In this example, the controller 104 may then determine antenna-to-antenna isolation and reduce transmit power as described above.

FIG. 4 is a flowchart of a method 400 for reducing the transmit power of the antenna 102, according to an example. Method 400 includes determining 401 an antenna-to-antenna isolation threshold. As noted above, the antenna-to-antenna isolation threshold may be based on a SAR threshold. That is, an entity such as a government may specify an allowable amount of RF energy that a human being can absorb, which is defined as the SAR threshold. Therefore, this SAR threshold is mapped to an antenna-to-antenna isolation threshold, which is compared with the measured value. The controller 104 then instructs the first antenna 102-1 to transmit 402 an RF signal. A second antenna 102-2 may be located on the same radio 310 or wireless network or a different radio/wireless network to receive RF signals.

In some examples, the RF signal is transmitted as part of a pilot packet. That is, in some examples, controller 104 operates transmit antenna 102 and receive antenna 102 simultaneously. However, in some instances, this may not be the case. For example, in a time division duplex (TDD) radio system, the first antenna 102-1 may transmit signals and the second antenna 102-2 may receive signals in a different time slot, and thus not simultaneously. In this example, the controller 104 monitors the status of the first antenna 102-1 when transmitting signals, and uses the pilot packet to instruct the second antenna 102-2 to start receiving signals. In a specific example, the determination of the antenna-to-antenna isolation value is done in a test mode. Therefore, the controller 104 can put the electronic device 100 into a test mode to determine the antenna-to-antenna isolation.

As described above, the controller 104 determines 403 an antenna-to-antenna isolation by subtracting the received signal power from the transmitted signal power to determine a delta. This difference is called antenna-to-antenna isolation and may have a unit of measurement in dB. If the antenna-to-antenna isolation is greater than a threshold, 404 judges yes, then the controller 104 may reduce 405 the transmit power of one of the first antennas 102-1. Measured values greater than the threshold may indicate that a recommended SAR threshold has been exceeded and that the RF transmit power should be reduced to reduce the amount of RF energy absorbed by a nearby user 208 .

If the antenna-to-antenna isolation is not greater than a threshold, 404 judges no, the controller 104 may maintain 406 a transmit power of the first antenna 102-1. Doing so allows more transmit power to be used in appropriate situations, ie when there are no human users 208 nearby.

5 illustrates a non-transitory machine-readable storage medium 514 for reducing the transmit power of the antenna 102 based on antenna-to-antenna isolation, according to an example. In order to realize its intended functions, an electronic device 100 includes various hardware components. Specifically, the electronic device 100 includes a processor and a machine-readable storage medium 514 . A machine-readable storage medium 514 is communicatively coupled to the processor. The machine-readable storage medium 514 includes a number of instructions 516, 518, 520, 522 for performing a specified function. The machine-readable storage medium 514 causes the processor to perform the specified functions of the instructions 516 , 518 , 520 , 522 . The machine-readable storage medium 514 can store data, programs, instructions, or any other machine-readable information that can be used to operate the electronic device 100 . The machine-readable storage medium 514 can store computer-readable instructions that can be processed or executed by the processor of the electronic device 100 . The machine-readable storage medium 514 may be an electronic, magnetic, optical, or other physical storage device containing or storing executable instructions. The machine-readable storage medium 514 can be, for example, random access memory (RAM), an electrically erasable programmable read-only memory (EEPROM), a storage device, an optical disc, and the like. The machine-readable storage medium 514 may be a non-transitory storage medium 514, where the term "non-transitory" does not include transitory propagation signals.

Referring to FIG. 5, the threshold determination instructions 516, when executed by the processor, cause the processor to determine an antenna-to-antenna isolation threshold based on a specific absorption rate (SAR) threshold. When executed by the processor, the RF signal transmitting instruction 518 can cause the processor to transmit an RF signal from a first antenna 102 - 1 of an electronic device 100 . The isolation determination instructions 520, when executed by the processor, may cause the processor to determine a day based on a difference between the transmitted RF signal and the RF signal as received by the second antenna 102-2 of the electronic device 100. Wire-to-antenna isolation. The transmit reduction instructions 522, when executed by the processor, may cause the processor to reduce the transmit power of a first antenna 102-1 in response to a determination that the antenna-to-antenna isolation is outside a threshold range.

100: Electronic device

102-1, 102-2: Antenna

104: Controller

Claims (13)

An electronic device comprising: a first antenna for transmitting a radio frequency (RF) signal; a second antenna for receiving the RF signal; and a controller for performing the following actions: based on the determining an antenna-to-antenna isolation from a difference between the transmitted RF signal and the received RF signal; and reducing a transmit power of the first antenna based on the antenna-to-antenna isolation being outside a threshold range, wherein the control A filter is to determine a material type that blocks the RF signal based on a value of the antenna-to-antenna isolation. The electronic device of claim 1, wherein the threshold range is based on a specific absorption rate (SAR) threshold. The electronic device according to claim 1, wherein the first antenna and the second antenna belong to different wireless networks. The electronic device of claim 3, wherein: the controller is to receive information associated with a power of the transmitted RF signal from a first wireless network chipset; and the controller is to receive information from a second wireless The network chipset receives information associated with a power of the received RF signal. The electronic device according to claim 1, wherein the threshold range is adapted to network traffic. The electronic device of claim 1, wherein the controller repeatedly determines an antenna-to-antenna isolation and reduces the transmit power until the antenna-to-antenna isolation is within the threshold range. The electronic device of claim 1, wherein the controller reduces the transmit power of the first antenna based on a degree of antenna-to-antenna isolation outside the threshold range. The electronic device according to claim 7, further comprising a database for mapping an antenna-to-antenna isolation value and an amount of reducing the transmit power. An electronic device comprising: a first radio having a first antenna for transmitting a radio frequency (RF) signal; a second radio having a second antenna for receiving the RF signal, wherein the first radio and the second radio operate in different frequency bands; a controller that: determines an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal; and reducing transmit power of a first antenna in response to the antenna-to-antenna isolation being outside a threshold; and a database for mapping antenna-to-antenna isolation values to materials that block the RF signal. The electronic device of claim 9, wherein the RF signal is transmitted as part of a pilot packet. The electronic device according to claim 9, wherein the controller reduces the transmit power of the first antenna based on the first radio. A non-transitory machine-readable storage medium comprising instructions that, when executed by a processor of an electronic device, cause the processor to: determine an antenna-to-antenna isolation based on a specific absorption rate (SAR) threshold Threshold; transmitting a radio frequency (RF) signal from a first antenna of an electronic device; determined based on a difference between the transmitted RF signal and the RF signal as received by a second antenna of the electronic device Antenna-to-antenna isolation; Responsive to a determination that the antenna-to-antenna isolation is outside a threshold range, reducing a transmit power of the first antenna; and determining a material type that blocks the RF signal based on a value of the antenna-to-antenna isolation. The non-transitory machine-readable storage medium of claim 12, wherein the instructions, when executed by the processor, further cause the processor to place the electronic device in a test mode to determine the antenna-to-antenna isolation.

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