IWR6843ISK-ODS: Critical radiation level when using beam collimation with lenses. (Vital-Sign-Lab use case)

Alexander Groeschel

Part Number: IWR6843ISK-ODS
Other Parts Discussed in Thread: MMWAVEICBOOST, IWR6843

Hello,

I want to use a lens to collimate the beam-path of a IWR6843ISK-ODS evaluation board in order to create a defined field of view for the use-case of the vital signs lab. Is there a critical threshold value of how much of the emitted signal energy may be focussed to a certain cross section area in to be safe of radiation damages of biological tissue (face skin, eye ball, ...)?

My ideal use case goal would be to narrow a solid angle from roughly +/-50° of the emission cone of the sender to a field of view of roughly +/-14° to illuminate a face at a distance of ca. 40cm from the emitter.

Best regards

Alexander

over 5 years ago

0 Akash Gondalia over 5 years ago

TI__Guru 50240 points

Hi Alexander

I cannot comment specifically on the effect of radar energy on human tissue. Please see this thread for more information on the subject.

Regards,

0 Alexander Groeschel over 5 years ago in reply to Akash Gondalia

Prodigy 100 points

Hello Akash,

after some research I have to come back with further questions for clarification:

As described earlier, I wonder, if the beam of a IWR6843ISK-ODS (Rev. A) antenna board may exceed radiation power levels that may be hazardous to human tissue, if a lens is used to collimate the beam. Specifically, the antenna board is planned to be used with the vital signs lab of the industrial toolbox, that utilizes only one TX-RX-pair, and the beam is planned to be directed at human tissue (e.g. a human face) at 45cm distance from the sender. I tried to estimate the compliance of the setup with the threshold values given in (IEEE Std C95.1TM-2019 and IEEE Std C95.1TM-2005) but for estimating the maximum incoming energy I would need more clarification:

1.) Where can I find the angular emmission characteristics of one TX-Antenna of the IWR6843-ODS (Rev. A) Board? (The "mmWaveICBoost and Antenna Module"-user guide provides an angular anntenna radiation pattern for the IWR6843-ODS on pp. 67-68, but in my understanding this is the combination of TX-emmission and RX-senstivity. Is this correct?)

2.) From Section 5.7 in the iwr6843 documenation (Document: SWRS219C –OCTOBER 2018–REVISED MAY 2020) the typical output power per one antenna is 12dbm which translates to 16mW. Is this the signal power used for one chirp?

3.) I would estimate the antenna surface of roughly 1 x 1 mm^2. So I would estimate the power density directly at the antenna as 16mW/mm^2. Could you confirm this?

4.) The vital signs demo specifies the signal as follows: chirp length 50µs, frame length 50ms, 2 chirps per frame. Is the tx-antenna only emmitting during one chirp or is there a continuous base signal emitted. This information would be crucial for me for estimating the signal energy in a time frame of 100ms (as this measure is crucial for radiation thresholds defined for pulsed RF signals in IEEE C95.1-2019).

5.) Can you further recommend basic equipment for measuring the microwave radiation energy at certain distances in the spectral range from 60-64 Ghz?

Thank you in advance,

Alexander

0 CHETHAN KUMAR Y.B. over 4 years ago in reply to Alexander Groeschel

TI__Mastermind 25835 points

Alexander,

You could refer to below standard applicable to limitation of Exposure compliance certification. With the lens we need to ensure we are not increasing the antenna gain such that we don’t violate the 10W/m^2 power density limits.

All the report and Test plan we have captured in our TI resource explorer.

https://dev.ti.com/tirex/explore/node?node=ANZCxyzbUGQoIA1DUZnmcQ__VLyFKFf__LATEST

Thanks and regards,

CHETHAN KUMAR Y.B.

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IWR6843ISK-ODS: Critical radiation level when using beam collimation with lenses. (Vital-Sign-Lab use case)