Reference Cavity

• The BPM was connected to 2 ports of the VNA and S parameters were measured.
• Vacuum seals were used this time.

Monopole Mode

• The measured resonant frequency is 230 MHz below the desired 15 GHz. But has increased 70 MHz after brazing.
• The Q values can be determined by plotting a smith chart.

• The unloaded Q factor is higher than before brazing, however the external Q is larger, making the Q factor larger than 500.
• Need to simulate to determine why the external Q factor is high, what can be done to correct this.

Position Cavity

• This time the correct feedthroughs were used.

S Parameter	Frequency /GHz	Loaded Q
S14	14.995	874
S21	14.996	809
S32	14.995	878
S43	14.996	811

• The frequencies are higher than the pre-brazing value of ~14.990 GHz, but just below 15 GHz.
• The Q is closer to the design value, but still too high.

• The external Q is not as high as before but still much larger than the value in simulation, ~600.

• Need to simulate to determine why the external Q factor is high, what can be done to correct this.

Cross Coupling

• All maximum cross couplings are below -40 dB.
• Much lower (remarkably lower) than measured previously.