AWR2944EVM: Is it possible to supply DCA1000EVM with RADAR_5V_IN input from AWR2944EVM ?

Dear Titouan - 

Thanks for the post and welcome to E2E!

No, this is not possible. If you look at J3 of the DCA1000EVM schematic you will see VCC5V_CONN, however then if you have a look at J7 of the AWR2944, you will see pins 1,2, and 3 are not connected. 

J3 on DCA1000EVM: 

J7 on AWR2944EVM: 

DCA1000 design files (includes schematic): https://www.ti.com/lit/zip/sprr350 

AWR2944EVM schematic: https://www.ti.com/lit/zip/sprr440