Devices, systems, and methods for radar-based artificial reality tracking using polarized signaling

1. A radar system comprising:

at least one radar device that:

transmits, to at least one transponder located within a physical environment surrounding a user, a frequency-modulated radar signal that has a first type of polarization;

receives signals that have a second type of polarization, the second type of polarization being different than the first type of polarization; and

comprises a plurality of receive antennas, wherein:

one of the receive antennas receives signals that are reflected from an object other than the at least one transponder and have a first type of polarization; and

another one of the receive antennas receives signals that are transmitted by the at least one transponder and have a second type of polarization; and

a processing device communicatively coupled to the at least one radar device, wherein the processing device:

detects a signal that has the second type of polarization and was returned to the at least one radar device from the at least one transponder in response to the frequency-modulated radar signal; and

calculates a distance between the at least one transponder and the at least one radar device and a distance between the object and the at least one radar device.

2. The radar system of claim 1 , wherein the second type of polarization is orthogonal relative to the first type of polarization.

3. The radar system of claim 1 , wherein:

the first type of polarization comprises linear polarization; and

the second type of polarization comprises circular polarization.

4. The radar system of claim 3 , wherein the at least one transponder comprises a device that:

receives the frequency-modulated radar signal comprising linear polarization;

changes the polarization of the frequency-modulated radar signal to circular polarization; and

returns the frequency-modulated radar signal with circular polarization to the at least one radar device.

5. The radar system of claim 2 , wherein the at least one radar device further receives signals that have the first type of polarization and the processing device further detects the received signals that have the first type of polarization.

6. The radar system of claim 2 , wherein the at least one radar device comprises at least one transmit antenna and at least one receive antenna, and

the at least one transmit antenna and the at least one receive antenna are disposed in a single package.

7. The radar system of claim 6 , wherein the at least one transmit antenna and the at least one receive antenna are separated by a distance less than 1.25 millimeters.

8. The radar system of claim 1 , wherein the signal returned to the at least one radar device from the at least one transponder in response to the frequency-modulated radar signal is insensitive to an orientation of the at least one transponder relative to an orientation of the at least one radar device.

9. The radar system of claim 1 , wherein:

the at least one radar device is secured to a first wearable device dimensioned to be worn by a user of an artificial reality system; and

the at least one transponder is secured to a second wearable device dimensioned to be worn by the user of the artificial reality system.

10. The radar system of claim 1 , wherein the processing device further:

determines, based at least in part on the distance between the at least one transponder and the at least one radar device, a change in a position of at least a portion of the user within the physical environment; and

facilitates modifying at least one virtual component of an artificial reality system to account for the change in the position of the portion of the user.

11. The radar system of claim 1 , wherein:

the at least one radar device is secured to a first vehicle; and

the at least one transponder is secured to a second vehicle, wherein the first vehicle is in proximity to the second vehicle.

12. The radar system of claim 1 , wherein:

the at least one radar device is secured to a robotic device; and

the at least one transponder is secured to an automation device, wherein the robotic device and the automation device are disposed in the same building.

13. The radar system of claim 1 , wherein a power transmission level of the frequency-modulated radar signal that has a first type of polarization is limited by a level of internal crosstalk within the at least one radar device.

14. A method comprising:

transmitting, by at least one radar device, to at least one transponder located within a physical environment surrounding a user, a frequency-modulated radar signal that has a first type of polarization;

receiving, by the at least one radar device, signals that have a second type of polarization, the second type of polarization being different than the first type of polarization, the at least one radar device comprising a plurality of receive antennas, wherein:

one of the receive antennas receives signals that are reflected from an object other than the at least one transponder and have a first type of polarization; and

another one of the receive antennas receives signals that are transmitted by the at least one transponder and have a second type of polarization;

detecting, by a processing device communicatively coupled to the at least one radar device, a signal that has the second type of polarization and was returned to the at least one radar device from the at least one transponder in response to the frequency-modulated radar signal; and

calculating, by the processing device, a distance between the at least one transponder and the at least one radar device and a distance between the object and the at least one radar device.

15. The method of claim 14 , wherein the second type of polarization is orthogonal relative to the first type of polarization.

16. The method of claim 14 , wherein:

the first type of polarization comprises linear polarization; and

the second type of polarization comprises circular polarization.

17. The method of claim 16 , wherein the at least one transponder comprises a device that:

receives the frequency-modulated radar signal comprising linear polarization;

changes the polarization of the frequency-modulated radar signal to circular polarization; and

returns the frequency-modulated radar signal with circular polarization to the at least one radar device.

18. A non-transitory computer-readable medium comprising computer-readable instructions that, when executed by at least one processor of a computing device, cause the computing device to:

transmit, from at least one radar device to at least one transponder located within a physical environment surrounding a user, a frequency-modulated radar signal that has a first type of polarization; and

receive, by the at least one radar device, signals that have a second type of polarization, the second type of polarization being different than the first type of polarization, the at least one radar device comprising a plurality of receive antennas, wherein:

one of the receive antennas receives signals that are reflected from an object other than the at least one transponder and have a first type of polarization; and

another one of the receive antennas receives signals that are transmitted by the at least one transponder and have a second type of polarization;

detect, by a processing device communicatively coupled to the at least one radar device, a signal that has the second type of polarization and was returned to the at least one radar device from the at least one transponder in response to the frequency-modulated radar signal; and

calculate, by the processing device, a distance between the at least one transponder and the at least one radar device and a distance between the object and the at least one radar device.