Transceiver having mixer/filter within receiving/transmitting cavity

1. A transceiver for receiving and/or transmitting signals, said transceiver comprising:

a block having a received signal cavity providing a waveguide for a received signal in use, and a locally generated signal cavity providing a waveguide for a locally generated signal in use, said cavities sharing a common plane in the block;

a mixer/filter assembly having a mixer, at least one filter and at least two mode converter portions, the mixer/filter assembly being mounted within the block, where a first mode converter portion of said mixer/filter assembly extends into the received signal cavity and a second mode converter portion of the mixer/filter assembly extends into the locally generated signal cavity, the mode converter portions of the mixer/filter assembly providing mode conversion of a received signal and the locally generated signal to a TEM mode, for propagation to the mixer, in use; and

a filter electrically connected to the mixer/filter assembly to provide an output signal in use of the transceiver to receive signals where said filter is disposed in a further cavity of the block where said further cavity is substantially perpendicular to the common plane.

2. A transceiver as claimed in claim 1 , wherein the mixer/filter assembly comprises a substrate mounted in the block, parallel to the common plane.

3. A transceiver as claimed in claim 1 , wherein the received signal cavity and the locally generated signal cavity comprise physical channels in the block.

4. A transceiver as claimed in claim 1 , wherein the further cavity comprises a cylindrical cavity and the electrically connected filter comprises a filter pin, sealed in a coaxial position in the further cavity.

5. A transceiver as claimed in claim 4 , wherein the filter pin is sealed in the further cavity by means of UV-cured glass.

6. A transceiver according to claim 1 for receiving and/or transmitting radio frequency signals, wherein, in use, said received signal cavity guides a radio frequency signal, and the filter disposed in the further cavity extracts an intermediate frequency signal generated by the mixer/filter assembly.

7. A transceiver according to claim 1 for use in receiving and/or transmitting signals having wavelengths of one millimeter or less.

8. A transceiver according to claim 1 , said block further having a horn antenna cavity providing at least part of a horn antenna for receiving and/or transmitting signals in use of the transceiver, the horn antenna cavity being coupled to the received signal cavity and sharing the common plane.

9. A transceiver according to claim 8 , comprising multiple sets of received signal, locally generated signal and horn antenna cavities sharing said common plane, each set having an electrically connected filter to provide an output signal in use of the transceiver to receive signals, the electrically connected filter being disposed in a further cavity substantially perpendicular to the common plane.

10. A transceiver according to claim 1 , wherein the mode converter portions of the mixer/filter assembly comprise antennas.

11. A transceiver according to claim 1 , wherein the mixer/filter assembly comprises diodes in an anti-parallel configuration for use in mixing a received signal with a locally generated signal.

12. A transceiver according to claim 11 , wherein the mixer/filter assembly comprises a pair of diodes in an anti-parallel configuration.

13. A transceiver according to claim 1 , wherein the mixer/filter assembly comprises one or more tuners for use in delivering the received signal and the locally generated signal to the mixer for mixing.

14. A transceiver according to claim 13 , wherein at least one of said one or more tuners is connected to the first mode converter portion of said mixer/filter assembly, having a minimized mismatch therewith and being adapted to optimize the match of the locally generated signal to the mixer, in use of the transceiver.

15. A transceiver according to claim 13 , wherein at least two of said one or more tuners comprise transmission lines connected between the mixer/filter assembly and the block to make a physical ground and hence reactive termination to reflect the received signal and the locally generated signal.

16. A transceiver according to claim 15 , wherein the lengths of the at least two tuners connected between the mixer/filter assembly and the block are tuned for coupling the received signal to the mixer, in use of the transceiver.

17. A transceiver according to claim 1 , wherein the filter which provides an output signal in use of the transceiver is connected to the mixer/filter assembly by means of bond wires.

18. A transceiver according to claim 11 , wherein the locally generated signal has a frequency, in use of the transceiver, at which the received signal cavity provides a purely reactive termination.

19. A transceiver according to claim 6 , wherein the intermediate frequency signal is substantially lower in frequency than the received signal or the locally generated signal such that the locally generated signal cavity acts as a high pass filter blocking the intermediate frequency signal.

20. A transceiver according to claim 4 , wherein the dimensions of the filter pin sealed in its coaxial position in the further cavity are optimized with respect to rejection of the locally generated signal and insertion loss to the output signal in use of the transceiver.

21. A transceiver according to claim 1 for use in receiving and/or transmitting signals having wavelengths of more than one millimeter.