IWR1443: Tx-Tx leakage

Hi Gennadii,

For Causes of the Leakage between Tx pairs we would have to see what is the nature of the leakage you see.

Contributing factor could be device, board and field all combined.

Based on that counter measure can be incorporated  in Design as well as post processing to avoid the leakage form causing detection errors.

For example - if leakage shows detection in close range detection  then application can use the High Pass Filter  setting  in the device to filter out these near reflections.

We will get back with more information. Please share more specifics of detection of needs and leakage seen to help you better.

Thank you,

Vaibhav

Hi Vaibhav,

The leakage is a signal from the reflector.

It's just a copy of signal U but having lower amplitude.

Regards,

Gennadii

Gennadii,

Just to give some background here:

   As you would know Tx to Rx coupling at board level would be present, In Radar systems this is also termed as Tx to Rx leakage signal (This is undesired component). This would be appearing at lower IF frequency of the spectrum (frequency is dependent on slope and location of dominant coupling path i,.e. board level, Antenna, Radome etc. Isolation between Tx and Rx on board level is >30dB. Signal beyond this isolation would appear in the lower IF part of the spectrum. High pass filter would suppress it maximum up to 40dB depending upon where it would appears in the IF spectrum (Hence higher antenna isolation is always better to reduce this leakage signal). 

Longer feed lines are susceptible for coupling (Grounded CPW transmission line works better compared to micro strip-line configuration) 

In the above case: We have two mechanism

1) Selecting right Tx chain through the profile configuration: In this configuration you could select right transmitter of your choice.

However in this case other transmitter chains (Not selected) would be enabled but would not be chirping.If your design doesn't have other transmitter active at all then below 2nd option is better.

2) In this option by selecting only desired Transmitter and receiver section completely shuts of other Tx and Rx pairs which are not selected.

Hence you would not see any leakages, from other transmitter which are not in use in the system.

These are screen shot from mmWave studio, however you could use the same APIs from the mmWave SDK as well to achieve same desired results. 

Thanks and regards,

CHETHAN KUMAR Y.B.

Hello Chethan,

We have done step (2). Electrical tape and foil was used. We still have 12 dB leakages. We have seen Tx leakage for open antenna using our software but not RadarStudio.

Regards,
Gennadii

Expirement_tx0_covered.zip

Hello, 

   Thanks for sharing the results,

From the images shared 1) Tx open and Tx covered couldn't see the difference between the images. I guess this is just a typo. I couldn't see the step 2 configuration in the images that is attached.

2) on the x-axis range bin where tx and Rx leakage seen seem to at higher distance than at where Antennas are located. Could you change the chirp, configuration and confirm this? It may be possible leakage would be coming from elsewhere.  

3) Typically to suppress Tx-Rx leakage at board level / Ramdome level mmWave absorber materials are used. Foils are not recommended.

https://www.cumingmicrowave.com/products/rubber-sheet-absorbers.html

4) Are you saying leakage is seen in your software but not in the Radar studio, Could you please share the results between two.

Typically in the design, higher Antenna isolation helps between Tx to Rx, Apart from that HPFs are used to attenuated the Tx / Rx leakage, Is there HPF corner frequencies are the same for both? 

Thanks and regards,

CHETHAN KUMAR Y.B.