Microstrip coupler combining transmit-receive signal separation and differential to single ended conversion
One embodiment relates to a coupler that can be used in a radar system. The coupler includes differential ports, an antenna port, a receiver port, a local port and a transmission path. The differential ports are configured to receive a differential signal. The antenna port is configured to output a transmitted signal and to input a received signal. The transmitted signal is derived from the differential signal. The receiver port is configured to output a portion or version of the received signal. The local port outputs a local signal, which is also derived from the differential signal. The transmission path is coupled to the differential ports, the antenna port, the receiver port and the local port. The transmission path typically has a length selected to derive or output the signals at the above ports.
1. A single coupler system, comprising:
differential ports of the single coupler configured to receive a differential signal from a differential signal source;
an antenna port of the single coupler configured to output a transmitted signal and to input a received signal;
a receiver port of the single coupler configured to output a portion of the received signal;
a local port of the single coupler configured to output a local signal; and
a transmission path coupled to the differential ports, the antenna port, the receiver port, and the local port.
2. The coupler of claim 1 , wherein the differential portions comprise a positive port and a negative port.
3. The coupler of claim 1 , wherein the transmitted signal and the local signal are single ended versions of the differential signal.
4. The coupler of claim 1 , wherein the differential signal is a radar signal.
5. The coupler of claim 1 , wherein the differential signal is a communications signal.
6. The coupler of claim 1 , wherein the local signal is a first portion of the differential signal and the transmitted signal is a second portion of the differential signal.
7. The coupler of claim 1 , further comprising an antenna to transmit the transmitted signal and to receive the received signal.
8. The coupler of claim 1 , further comprising a receiver to receive the received signal from the receiver port.
9. The coupler of claim 1 , wherein the transmission path is circular shaped and has a length of an odd integer multiple of one and a half wavelength.
10. The coupler of claim 9 , wherein a transmission path length from a positive port of the differential ports to the antenna port is an odd integer multiple of ¼ a wavelength.
11. The coupler of claim 10 , wherein a transmission path length from the antenna port to the receiver port is an odd integer multiple of ¼ a wavelength.
12. The coupler of claim 1 , wherein the differential signal has a frequency of about 77 GHz.
13. A signal conversion system comprising:
a receiver configured to process a received signal;
a local component configured to process a local signal;
a source to generate a differential signal; and
a single coupler system, comprising:
a circular transmission path;
differential ports of the single coupler on the transmission path configured to receive the differential signal, the differential ports comprising a first port and a second port;
an antenna port of the single coupler configured to provide a transmitted signal and input a received signal, the transmitted signal is a single ended signal converted from the differential signal;
a receiver port of the single coupler isolated from the differential signal and configured to provide the received signal from the antenna port; and
a local port of the single coupler configured to provide a local signal converted from the differential signal.
14. The system of claim 13 , wherein the receiver is coupled to the local component and compares the received signal with the local signal to determine delay.
15. The system of claim 14 , wherein the delay is utilized to determine distance for a radar application.
16. The system of claim 13 , wherein the received signal is a communication signal.
17. A method of converting signals comprising:
receiving a differential signal at differential ports of a single coupler system;
providing a transmitted signal at an antenna port of the single coupler;
inputting a received signal at the antenna port of the single coupler;
providing the received signal at a receiver port of the single coupler; and
providing a local signal at a local port of the single coupler.
18. The method of claim 17 , further comprising comparing the received signal with the local signal to determine delay in the received signal.
19. The method of claim 17 , wherein providing the transmitted signal comprises converting a portion of the differential signal to a single ended signal having about half the power of the differential signal.
20. The method of claim 17 , further comprising a receiver that obtains the received signal from the receiver port.