Radar system

1. A waveguide assembly for use in a radar, the waveguide assembly being fabricated from a di-electric material and comprising:

i. a beamsplitter which comprises a right circular cylinder having a quarter wave air gap substantially along a centreline of the right circular cylinder; and

ii. a waveguide on a port of the beamsplitter.

2. The waveguide assembly of claim 1 , wherein the waveguide assembly comprises four ports.

3. The waveguide assembly of claim 2 , wherein the four ports comprise the following:

i. a transmit input arranged to receive a signal from a source;

ii. a receive output arranged to direct a return signal to a receiver;

iii. an output port; and

iv. a load port.

4. The waveguide assembly of claim 2 , further comprising a matching transformer on at least some of the ports.

5. The waveguide assembly of claim 3 , wherein a path length from the transmit input port to the output port is of substantially the same length as a path length from the output port to the receive output port.

6. The waveguide assembly of claim 4 , further comprising a matching material between at least some of the matching transformers and the beamsplitter, and wherein preferably wherein the matching material has a dielectric constant substantially equal to that of the right cylinder and other components of the waveguide assembly.

7. The waveguide assembly of claim 1 , further comprising a frame to hold the waveguide assembly, wherein the frame is an E-plane split waveguide frame, and wherein optionally one or each portion of the frame is arranged to transition a channel of a first shape to a channel of a second shape, and wherein the first shape is substantially circular and the second shape is substantially rectangular.

8. The waveguide assembly of claim 3 , further comprising a load associated with the load port.

9. The waveguide assembly of claim 4 , wherein a further matching transformer is arranged to feed the load, and wherein the further matching transformer comprises at least one of the following:

i. a substantially planar end region adjacent the beamsplitter;

ii. a face that is of complementary shape to that of the beamsplitter adjacent the beamsplitter; and

iii. a face that is substantially convex.

10. The waveguide assembly of claim 9 , further comprising an adjustor arranged to allow the complex impedance of the load to be varied, wherein optionally the adjustor is one of the following:

i. a mechanical mechanism arranged to move the further matching transformer relative to the beamsplitter; or

ii. an electrical adjustor arranged to vary an electrical parameter of the load.

11. The waveguide assembly of claim 1 , further comprising an antenna in association with the output port, wherein the antenna has a feed which is substantially co-axial with a beam path of a beam leaving the output port, and wherein optionally the beam path is shared between an output wave leaving the beamsplitter and a return signal being input to the beamsplitter from the antenna.

12. The waveguide assembly of claim 1 for use in a radar of one of the following types:

i. FMCW radar;

ii. Pulse radar; or

iii. FMICW radar.

13. A radar head comprising a waveguide assembly according to claim 1 .

14. A radar incorporating a waveguide assembly according to claim 1 .

15. The radar according to claim 14 , wherein a frequency modulation of the radar is arranged to be swept over a frequency range of up to substantially 2% of a transmit frequency.

16. The radar according to claim 14 , wherein a load is provided on a port of the beamsplitter.

17. A radar incorporating a radar head according to claim 13 .

18. The radar according to claim 14 , wherein the radar is a millimetre-wave radar.

19. The radar according to claim 14 , wherein the radar is one of the following types:

i. FMCW radar;

ii. Pulse radar; or

iii. FMICW radar.

20. The radar according to claim 14 , wherein the radar further comprises additional quasi-optical elements incorporated into a beam path.