WO2022086488A1

WO2022086488A1 - Transmission power reduction

Info

Publication number: WO2022086488A1
Application number: PCT/US2020/056311
Authority: WO
Inventors: Chin-Hung Ma; Chih-Hung Chien; Hsin-Chih Lin
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2022-04-28
Also published as: TW202218358A; TWI795802B

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

TRANSMISSION POWER REDUCTION

BACKGROUND

[0001] Electronic devices include wireless antennas to transmit information between electronic devices that are not physically connected to one another. Antennas wirelessly communicate with other antennas through a wireless network. Different wireless networks include different communication protocols and the antennas that are a part of a wireless network communicate in compliance with those 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 respective antenna for each wireless network through which it communicates. For example, an electronic device with a Wi-Fi antenna may transmit and receive data via the Wi-Fi network. If the electronic device includes an LTE antenna it may also communicate via the LTE network.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The accompanying drawings illustrate various examples of the principles described herein and are part of the specification. The illustrated examples are given merely for illustration, and do not limit the scope of the claims.

[0003] Fig. 1 is a block diagram of an electronic device to reduce antenna transmission power, according to an example.

[0004] Fig. 2 depicts the electronic device to reduce antenna transmission power, according to an example. [0005] Fig. 3 is a block diagram of an electronic device to reduce antenna transmission power, according to an example.

[0006] Fig. 4 is a flowchart of a method for reducing antenna transmission power, according to an example.

[0007] Fig. 5 depicts a non-transitory machine-readable storage medium for reducing antenna transmission power, according to an example.

[0008] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

DETAILED DESCRIPTION

[0009] Electronic devices include any number of antennas to facilitate wireless communication. For example, an electronic device may include a Wi-Fi antenna which allows the electronic device to transmit and receive information via 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 via an LTE network. Each of these different networks incorporate different communication protocols. As the different wireless networks have different operating parameters and communication protocols, each may be particularly tailored to a particular environment. Accordingly, an electronic device with multiple different antennas may transmit and receive information wirelessly under a number of different circumstances.

[0010] While wireless communication has undoubtedly shaped the way in which society communicates with one another, some characteristics limit their more thorough implementation. For example, in a user environment, objects may influence the radio frequency (RF) signals through which the information is transmitted. [0011] In some examples, the RF waves may be absorbed by the human body. The absorption of the RF waves by the human body may cause harm to the individual. Accordingly, some entities such as governments regulate communications devices by imposing a restriction on how much RF energy they may emit so as to limit the amount of RF energy a user absorbs. This restriction may be referred to as a specific absorption rate (SAR) threshold. The effect of the RF waves on the human body may be reduced by reducing the RF transmission power. Human bodies and other objects may also reflect the RF signals. That is, a human body close to the antenna may result in RF signals that are higher or lower due to the human body blocking or reflecting the RF signals.

[0012] Accordingly, the present specification describes electronic devices and non-transitory machine-readable storage medium that reduce the RF transmission power when a human is detected nearby. More specifically, a human near a transmitting antenna may impact the rate at which RF signal power dissipates between a transmitting and receiving antenna. An antenna-to- antenna isolation may be determined to determine blockage of RF transmission. The antenna-to-antenna isolation being outside of a threshold range is indicative that some object, such as a human body, is blocking the RF signal. The transmission power may then be altered to reduce the effect of the RF waves on the user. In an example, the present specification describes electronic devices that reduce antenna transmission power to meet a particular SAR threshold.

[0013] Specifically, the present 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 the RF signal, a controller uses a second antenna to receive the RF signal transmitted from the first antenna. The controller monitors the power at both the transmitting and receiving antenna to determine if the antenna-to-antenna isolation varies to greater than a threshold degree. 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 the transmit power based on the antenna isolation value. In one particular example, the variation may indicate that a human body might be close enough to the antenna that the transmission power of the antenna should be reduced to reduce the SAR level.

[0014] Specifically, the present specification describes an electronic device. The electronic device includes a first antenna to transmit a radio frequency (RF) signal and a second antenna to receive 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 transmission power of the first antenna based on the antenna-to isolation being outside of a threshold range.

[0015] In another example, the electronic device includes a first radio having a first antenna to transmit a radio frequency (RF) signal. A second radio has a second antenna to receive the RF signal. In this example, the first radio and second radio operate in different frequency bands. The electronic device also includes a controller to 1 ) determine an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal and 2) responsive to the antenna-to-antenna isolation being outside of a threshold range, reduce a transmission power of the first antenna.

[0016] The present specification also describes a non-transitory machine- readable storage medium comprising instructions, when executed by a processor of an electronic device, that cause the processor to determine an antenna-to-antenna isolation threshold based on a specific absorption rate (SAR) threshold. The machine-readable storage medium also includes instructions to, when executed by the processor, cause the processor to transmit a radio frequency (RF) signal from the first antenna of an electronic device and determine an antenna-to-antenna isolation based on a difference between a transmitted RF signal and the RF signal as received by a second antenna of the electronic device. The machine-readable storage medium includes, when executed by the processor, to cause the processor to, responsive to a determination that the antenna-to-antenna isolation is outside a threshold range, reduce a transmission power of the first antenna. [0017] As used in the present specification and in the appended claims, the term, “controller” may be a processor, an application-specific integrated circuit (ASIC), a semiconductor-based microprocessor, a central processing unit (CPU), and a field-programmable gate array (FPGA), and/or other hardware device.

[0018] The memory may include a computer-readable storage medium, which computer-readable storage medium may contain, or store computer- usable program code for use by or in connection with an instruction execution system, apparatus, or device. The memory may take many types of memory including volatile and non-volatile memory. For example, the memory may include Random Access Memory (RAM), Read Only Memory (ROM), optical memory disks, and magnetic disks, among others. The executable code may, when executed by the respective component, cause the component to implement at least the functionality described herein.

[0019] Further, as used in the present specification and in the appended claims, the term “antenna-to-antenna isolation” refers to a difference between a transmitted signal strength and a received signal strength. For example, the antenna-to-antenna isolation may refer to the percentage of the transmission signal that is received may be defined as the antenna-to-antenna isolation. The antenna-to-antenna isolation value may have a unit of measurement of decibels (dB).

[0020] Turning now to the figures, Fig. 1 is a block diagram of an electronic device 100 to reduce antenna 102 transmission power, according to an example. As described above, the electronic device 100 controls RF transmitting power. Specifically, this is done by detecting antenna-to-antenna isolation. Detecting antenna-to-antenna isolation may be used to determine whether a human is close to the electronic device 100 or not. That is, compared with air, the human body has low impedance such that the human body being close to the electronic device 100 may change the antenna-to-antenna isolation. In such a situation, the RF transmission power may be reduced to ensure that the electronic device 100 does not emit too much RF energy when a human is nearby. That is, the RF transmission power may be reduced to comply with a specific absorption rate (SAR) threshold which is deemed safe for humans. [0021] The electronic device 100 may be of a variety of types including a desktop computer, a laptop computer, a tablet, a smart phone, or any other electronic device 100 or any other electronic device 100 that includes wireless antennas 102.

[0022] The electronic device 100 includes a first antenna 102-1 to transmit a RF signal and a second antenna 102-2 to receive the RF signal. As described above, via these antennas 102, the electronic device 100 may wirelessly transmit and receive information. In the present electronic device 100, these antennas 102 may be used to determine an antenna-to-antenna isolation, which antenna-to-antenna isolation value may be used to 1 ) determine a material blocking an RF signal and 2) determine whether or not to reduce the RF transmission power. The antennas 102 may pertain to different wireless networks. Examples of wireless networks include a Wi-Fi network and an LTE network.

[0023] The electronic device 100 also includes a controller 104. As described above, “controller” refers to various hardware components, which include a processor and memory. The processor includes the circuitry to retrieve executable code from the 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 circumstance, there may be a difference between a transmitted RF signal and a received RF signal. The percentage of the transmission signal that is received may be defined as the antenna-to-antenna isolation. In other words, the antenna-to-antenna isolation refers to a difference between a transmission signal power and a received signal power. The power of a signal may have a unit of measurement of decibel-milliwatts (dBm) and a difference between a transmitted and received signal may have a unit of measurement of decibels (dB). A specific numeric example is now provided. In this example, the first antenna 102-1 may be transmitting at a strength of 1000 milliwatts (mW) which may also be described as 30 dBm. The second antenna 102-2 may receive the signal at a strength of 100 mW or 20 dBm. Accordingly, the antenna-to-antenna isolation for this configuration may be 10 dB.

[0024] Throughout the course of use, the antenna-to-antenna isolation between two antennas 102 on the electronic device 100 may vary to a particular degree. That is, for an expected antenna-to-antenna isolation of X, a tolerated variance may be ±Y, such that the threshold range for an acceptable antenna- to-antenna isolation is X± Y. That is, the threshold range against which a measured antenna-to-antenna isolation value is measured accommodates for network traffic. If a measured antenna-to-antenna isolation is outside of this range, it may indicate that some material or object is blocking the RF transmission path. If the measured antenna-to-antenna isolation is different enough from the acceptable range, it may indicate that the transmission power should be reduced, for example to prevent undue RF energy absorption by a nearby human.

[0025] Accordingly, when the electronic device 100 is connected to an access point or a base station, the first antenna 102-1 is transmitting signals. The controller 104 monitors the transmission 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 transmission power to obtain an antenna-to-antenna isolation. The measurement of the receive signal power may be continuous or may be periodic. For example, the controller 104 may sample the RF received signal strength every two seconds.

[0026] When the environment is stable, the received power should be within the range X± Y. Under these circumstances, a full transmission power is maintained for the first antenna 102-1 . By comparison, when the antenna-to- antenna isolation is outside this threshold range, the controller 104 may reduce a transmission power of the first antenna 102-1 .

[0027] In other words, the controller 104 determines whether the antenna-to- antenna isolation is outside of a threshold range, X± Y, and reduces the transmission power of the first antenna 102-1 when the antenna-to-antenna isolation is outside of this range. [0028] In one example, the threshold range is based on a specific absorption rate (SAR) threshold. That is, the SAR threshold may be a value indicating a safe amount of RF energy that a human may absorb. That is, the upper bound of the antenna-to-antenna isolation may map to a SAR threshold, past which there may be harmful effects to a human. Accordingly, any measured antenna- to-antenna isolation above this antenna-to-antenna isolation threshold indicates a SAR level above the SAR threshold.

[0029] The controller 104 also reduces a transmission power of the first antenna based on the antenna-to-antenna isolation being outside of a threshold range. As described above, an antenna-to-antenna isolation being outside of a threshold range may indicate that a human user is close enough to the electronic device 100 to be exposed to the RF energy of the electronic device 100.

[0030] Returning to the example where the antenna-to-antenna isolation threshold indicates a SAR threshold, when the measured antenna-to-antenna isolation value is greater than the antenna-to-antenna isolation threshold, the transmission power of the first antenna 102-1 is reduced such that the SAR levels are below the SAR threshold, and thereby safe for the user.

[0031] In some examples, the controller 104 reduces the transmission power of the first antenna 102-1 based on the wireless network to which the first antenna 102-1 pertains. As a particular example, the antenna-to-antenna isolation threshold may indicate that a threshold received power value of 15 dBm is acceptable. Accordingly, if the controller 104 measures a receive signal power of 20 dBm, then the controller 104 may reduce the transmission 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 24 dBm. Accordingly, the controller 104 may reduce the power of the first antenna 102-1 by 9 dB to comply with the antenna-to-antenna-isolation threshold.

[0032] In some example, the controller 104 determines a type of material that is blocking the RF signal based on a degree to which the antenna-to-antenna isolation is outside of the threshold range. For example, in a test, an antenna- to-antenna isolation was measured across different frequency ranges and with different materials adjacent the antennas 102. Table 1 below presents the results of that test.

Table (1)

[0033] As depicted in Table 1 , different materials have a different impact on the signal attenuation. Accordingly based on the antenna-to-antenna isolation value, the controller 104 may determine a type of material blocking the RF signal. Taking the particular case of a 5150 MHz spectrum, the controller 104 may determine that a human is within a threshold distance in front of the electronic device 100 when the measured antenna-to-antenna isolation value is between -24.9 dB and -28.4 dB.

[0034] Accordingly, the present specification describes an electronic device 100 that reduces antenna 102 transmission power when the antenna-to- antenna isolation is outside of a threshold range. Rather than permanently reducing transmission power to comply with a SAR threshold or reducing transmission power when the electronic device 100 is in a particular mode such as a tablet mode, the present electronic device 100 allows full transmission power when permitted, i.e., a human is not close to the electronic device 100, and reduces the transmission power just when a user is nearby.

[0035] Fig. 2 depicts the electronic device 100 to reduce antenna 102 transmission power, according to an example. As described above, an electronic device 100, such as a laptop computer, may have any number of antennas 102 to allow for wireless communication with other electronic devices 100. Antenna-to-antenna isolation may be used to determine whether an object, such as a user 206 is blocking the RF signals. Blockage of RF signals may impact antenna performance. The antenna-to-antenna isolation may also identify whether RF energy is being absorbed by the user 206, which absorption may be harmful to the user 206.

[0036] The absorption of the RF energy may be reduced by reducing the transmission power of the first, and transmitting, antenna 102-1 until it reaches a safe level, which safe level may be defined as an antenna-to-antenna isolation threshold below a recommended value.

[0037] Fig. 2 also depicts the controller 104 and a database 208 that aid in the determination of the antenna-to-antenna isolation and the reduction of the transmission power of the first antenna 102-1 . The controller 104 and database 208 are depicted in dashed lines to indicate their position internal to the electronic device 100.

[0038] As described above, the controller 104 may determine which material is blocking the RF signal based on the antenna-to-antenna isolation value. Accordingly, the electronic device 100 may include a database 208 to map antenna-to-antenna isolation values to materials that may be blocking the RF signal. For example, the database 208 may include a lookup table such as Table (1 ) to identify, for a frequency band of the transmission signal, what material a particular measured antenna-to-antenna isolation value indicates. [0039] As a first example, when taken in a 5825 MHz regime, a measured antenna-to-antenna isolation value may be -35 dB, thus indicating a human body is blocking the RF signal. By comparison, a measured antenna-to- antenna isolation value of -18 dB may indicate that a metal material, or metal object, is blocking the RF signal.

[0040] A specific example is now provided where the antennas 102 are wireless local area network (WLAN) antennas, with a transmitting signal power of 20 dBm (100 milliwatts) for the 5-6 Gigahertz (GHz) channels. In this example, the antenna-to-antenna isolation threshold may correspond to a SAR threshold of 1 .6 milliwatt per gram (mW/g). In this example, the controller 104 determines that at an antenna-to-antenna isolation for the electronic device 100 is -25.4 dB. From this antenna-to-antenna isolation, it is determined that the SAR for this electronic device 100 and antenna power setup is 1 .75 mW/g, which is greater than the SAR threshold. [0041] Accordingly, the controller 104 may reduce the transmission power for the first antenna 102-1 and may test the antenna-to-antenna isolation again. In this example, the controller 104 may reduce the transmission power of the first antenna to 18.5 dBm, which may map to a SAR level of 1 .25 mW/g and thus comply with the SAR threshold. The controller 104 may then re-evaluate the antenna-to-antenna isolation to verify it has a value within the threshold range. Note that this particular example provides a mapping between a maximum transmitting power and SAR levels. Such a value may be dependent upon a variety of characteristics including the electronic device 100. Accordingly, each electronic device may be associated with a mapping between antenna-to- antenna isolation values, transmission power values, and SAR thresholds.

[0042] In some examples, the controller 104 reduces the transmission power of the first antenna 102-1 based on a degree to which the antenna-to-antenna isolation is outside the threshold range. Accordingly, the database 208 may map antenna-to-antenna isolation values with an amount by which to reduce the transmission power. For example, if the antenna-to-antenna isolation value is measured to be -28.4 dB, the controller 104 may, relying on an entry in the database 208, reduce the transmission power by a first amount. By comparison, if the antenna-to-antenna isolation value is measured to be -24.9 dB, the controller 104 may, again relying on an entry in the database 208, reduce the transmission power by a second amount, which second amount may be less than the first amount.

[0043] In another example, the controller 104 reduces the transmission power of the first antenna 102-1 by a set amount, and tests the isolation again to determine if it is still outside of the threshold range. That is, the controller 104 may iteratively determine an antenna-to-antenna isolation and incrementally reduce the transmission power until the antenna-to-antenna isolation is within the threshold range.

[0044] Fig. 3 is a block diagram of an electronic device 100 to reduce antenna 102 transmission power, according to an example. In the example depicted 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, the first radio 310-1 and the second radio 310-2 may pertain to different wireless networks.

[0045] That is, in some examples, the electronic device 100 has multiple radios 310 that have overlapping frequency signals. In this example, a first antenna 102-1 of the first radio 310-1 may be used to transmit and a second radio 310-2 may be used to capture the radio signal through the second antenna 102-2. As a particular example, an LTE and Wi-Fi antenna may both operate within the 5 GHz frequency range. In this example, the first antenna 102-1 may be part of a Wi-Fi radio to transmit the signal and the second antenna 102-2 may be part of the LTE radio to receive the signal. Similar to as described above, the controller 104 may determine the antenna-to-antenna isolation between these two antennas 102-1 , 102-2 to determine whether, and an amount of transmission power reduction to trigger. Using antennas 102 from different radios 310 may be based on the sensitivity of the radio 310 to power fluctuations. For example, the second radio 310-2 radio may be more sensitive to power changes thus the antenna-to-antenna isolation measurement may be more precise and/or reliable.

[0046] In this example, the controller 104 receives information associated with the transmitted RF signal power from a first wireless network chipset 312-1 and receives information associated with the received RF signal power from a second wireless network chipset 312-2. When the transmitted and received RF signal are in the same radio, or pertain to the same wireless network as depicted in Fig. 1 , the controller 104 may directly communicate with the antennas 102. However, when the transmitted and received RF signals are from different radios 310, or pertain to different wireless networks, the controller 104 may rely on intermediary chipsets 312 to collect the information regarding signal power. In this example, the controller 104 may then determine the antenna-to-antenna isolation and reduce the transmission power as described above.

[0047] Fig. 4 is a flowchart of a method 400 for reducing antenna 102 transmission power, according to an example. The method 400 includes determining 401 an antenna-to-antenna isolation threshold. As described above, the antenna-to-antenna isolation threshold may be based on a SAR threshold. That is, an entity, such as a government, may dictate an allowable amount of RF energy that may be absorbed by a human, which allowable amount of energy is defined as the SAR threshold. Accordingly, this SAR threshold is mapped to an antenna-to-antenna isolation threshold against which measured values are compared. The controller 104 then instructs the first antenna 102-1 to transmit 402 an RF signal. A second antenna 102-2, which may be on the same radio 310 or wireless network or on a different radio/wireless network receives the RF signal.

[0048] In some examples, the RF signal is transmitted as part of a pilot packet. That is, in some examples, the controller 104 operates the transmission and receiving antennas 102 simultaneously. However, in some examples, this may not be the case. For example, in a time-division duplex (TDD) radio system, the first antenna 102-1 may transmit the signal and the second antenna 102-2 may receive the signal in a different time slot, and therefore not simultaneously. In this example, the controller 104 monitors the status when the first antenna 102-1 transmits the signals and use the pilot packet to instruct the second antenna 102-2 to start receiving the signal. In one particular example, the determination of the antenna-to-antenna isolation value is done within a test mode. Accordingly, the controller 104 may place the electronic device 100 in a test mode to determine the antenna-to-antenna isolation.

[0049] The controller 104 determines 403 an antenna-to-antenna isolation by, as described above, subtracting the received signal power from the transmission signal power to determine a delta. This delta, which may have a unit of measurement of dB, is referred to as the antenna-to-antenna isolation. If the antenna-to-antenna isolation is greater than a threshold, 404 determination YES, the controller 104 may reduce 405 a transmission power of the first antenna 102-1. The measured value being greater than the threshold may indicate that a recommended SAR threshold has been surpassed and RF transmission power should be reduced to reduce the amount of RF energy absorbed by a nearby user 208. [0050] If the antenna-to-antenna isolation is not greater than a threshold, 404 determination NO, the controller 104 may maintain 406 a transmission power of the first antenna 102-1 . Doing so allows for more transmission power to be used in circumstances where appropriate, i.e., there is no human user 208 nearby.

[0051] Fig. 5 depicts a non-transitory machine-readable storage medium 514 for reducing antenna 102 transmission power based on an antenna-to-antenna isolation, according to an example. To achieve its desired functionality, an electronic device 100 includes various hardware components. Specifically, an electronic device 100 includes a processor and a machine-readable storage medium 514. The machine-readable storage medium 514is communicatively coupled to the processor. The machine-readable storage medium 514includes a number of instructions 516, 518, 520, 522 for performing a designated function. The machine-readable storage medium 514 causes the processor to execute the designated function of the instructions 516, 518, 520, 522. The machine-readable storage medium 514 can store data, programs, instructions, or any other machine-readable data that can be utilized to operate the electronic device 100. Machine-readable storage medium 514 can store computer readable instructions that the processor of the electronic device 100 can process, or execute. The machine-readable storage medium 514 can be an electronic, magnetic, optical, or other physical storage device that contains or stores executable instructions. Machine-readable storage medium 514 may be, for example, Random Access Memory (RAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a storage device, an optical disc, etc. The machine-readable storage medium 514 may be a non-transitory machine-readable storage medium 514, where the term “non-transitory” does not encompass transitory propagating signals.

[0052] Referring to Fig. 5, 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. RF signal transmit instructions 518, when executed by the processor, may cause the processor to, transmit an RF signal from a first antenna 102-1 of an electronic device 100. Isolation determination instructions 520, when executed by the processor, may cause the processor to, determine an antenna-to- antenna isolation based on a difference between the transmitted RF signal and the RF signal as received by a second antenna 102-2 of the electronic device 100. Transmission reduction instructions 522, when executed by the processor, may cause the processor to, responsive to a determination that the antenna-to- antenna isolation is outside a threshold range, reduce a transmission power of the first antenna 102-1 .

Claims

CLAIMS What is claimed is:

1 . An electronic device, comprising: a first antenna to transmit a radio frequency (RF) signal; a second antenna to receive the RF signal; and a controller to: determine an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal; and reduce a transmission power of the first antenna based on the antenna-to-antenna isolation being outside of a threshold range.

2. The electronic device of claim 1 , wherein the threshold range is based on a specific absorption rate (SAR) threshold.

3. The electronic device of claim 1 , wherein the first antenna and the second antenna pertain to different wireless networks.

4. 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 associated with a power of the received RF signal from a second wireless network chipset.

5. The electronic device of claim 1 , wherein the controller is to determine a type of material blocking the RF signal based on a value of the antenna-to- antenna isolation.

6. The electronic device of claim 1 , wherein the threshold range accommodates for network traffic.

7. The electronic device of claim 1 , wherein the controller iteratively determines an antenna-to-antenna isolation and reduces the transmission power until the antenna-to-antenna isolation is within the threshold range.

8. The electronic device of claim 1 , wherein the controller is to reduce the transmission power of the first antenna based on a degree to which the antenna-to-antenna isolation is outside of the threshold range.

9. The electronic device of claim 8, further comprising a database to map antenna-to-antenna isolation values with an amount by which to reduce the transmission power.

10. An electronic device, comprising: a first radio having a first antenna to transmit a radio frequency (RF) signal; a second radio having a second antenna to receive the RF signal, wherein the first radio and the second radio operate in different frequency bands; and a controller to: determine an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the received RF signal; and responsive to the antenna-to-antenna isolation being outside of a threshold range, reduce a transmission power of the first antenna.

11 . The electronic device of claim 10, wherein the RF signal is transmitted as part of a pilot packet.

12. The electronic device of claim 10, further comprising a database to map antenna-to-antenna isolation values to materials which block the RF signal.

13. The electronic device of claim 10, wherein the controller reduces the transmission power of the first antenna based on the first radio.

14. A non-transitory machine-readable storage medium comprising instructions, when executed by a processor of an electronic device, cause the processor to: determine an antenna-to-antenna isolation threshold based on a specific absorption rate (SAR) threshold; transmit a radio frequency (RF) signal from a first antenna of an electronic device; determine an antenna-to-antenna isolation based on a difference between the transmitted RF signal and the RF signal as received by a second antenna of the electronic device; and responsive to a determination that the antenna-to-antenna isolation is outside a threshold range, reduce a transmission power of the first antenna.

15. The non-transitory machine-readable storage medium of claim 14, 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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