Waveguide attenuator having coaxial probes

1. A digital attenuator, comprising:

a waveguide, the waveguide receiving a signal to be attenuated, and outputting the attenuated signal;

at least one bit comprising at least one coaxial probe in communication with the waveguide to couple energy to and from a signal traveling within the waveguide;

at least one coaxial line in communication with the at least one coaxial probe effective to receive the energy coupled from a signal by the at least one coaxial probe and including a switch,

wherein the switch reflects the coupled energy back into the waveguide or passes the coupled energy to a resistive termination.

2. The attenuator of claim 1 , further comprising a plurality of bits.

3. The attenuator of claim 1 , further comprising seven bits.

4. The attenuator of claim 3 , wherein the seven bits include a 1.6 dB bit, a 0.8 dB bit, a 0.4 dB bit, a 0.2 dB bit, a 0.1 dB bit, a 0.05 dB bit, and a 0.025 dB bit.

5. The attenuator of claim 1 , wherein the at least one bit comprises two coaxial probes effective to couple equal amounts of energy to and from a signal traveling within the waveguide.

6. The attenuator of claim 1 , wherein attenuation error is less than ±0.03 dB over an entire attenuation range of about 0 to 3 dB.

7. The attenuator of claim 1 , wherein the maximum attenuation of a signal is about 3 dB.

8. The attenuator of claim 1 , wherein the waveguide includes first and second coaxial connectors having first and second coaxial probes configured to introduce a signal into and out of the waveguide.

9. The attenuator of claim 1 , further comprising ferrite circulators or isolators configured to isolate an input and an output signal.

10. The attenuator of claim 1 , wherein the signal is in the X-band of the electromagnetic spectrum and has a maximum band-width of about 40 MHz.

11. The attenuator of claim 1 , wherein the attenuation is insensitive to incident power levels up to and including about 1000 watts.

12. The attenuator of claim 1 , wherein the attenuation is insensitive to temperature in the range of about −40 degrees Celsius to about 75 degrees Celsius.

13. The attenuator of claim 1 , wherein the attenuator is configured to switch in about 400 ns.

14. The attenuator of claim 1 , wherein the switch is a PIN diode.

15. The attenuator of claim 1 , wherein the at least one bit is configured to be driven by an analog to digital driver.

16. The attenuator of claim 1 , wherein the waveguide is in a racetrack configuration.

17. The attenuator of claim 1 , wherein insertion losses are below about 3 dB.

18. A method of attenuating an RF signal, comprising:

inputting an RF signal into an attenuator having a waveguide;

sending a digital command to at least one bit to toggle a switch;

attenuating the RF signal by an amount corresponding to the at least one bit;

outputting the RF signal attenuated by an amount corresponding to the at least one bit plus or minus about 0.03 dB.

19. The method of claim 18 , further comprising attenuating the RF signal by about 3 dB.

20. The method of claim 18 , wherein the attenuator includes at least one coaxial probe for coupling energy out of the RF signal for attenuation.

21. The method of claim 18 , further comprising sending digital command signals to a plurality of bits.

22. The method of claim 18 , further comprising sending digital command signals to seven bits.

23. The method of claim 22 , wherein the seven bits include eleven coaxial probes each having a switch that opens or closes in response to the digital command signals.

24. The method of claim 18 , wherein the attenuator switches in about 400 ns.

25. The method of claim 18 , wherein the at least one bit is insensitive to incident power up to about 1000 watts and temperature between about −40 degrees Celsius and about 75 degrees Celsius.