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A traveling-wave tube (TWT) amplifies RF signals in the microwave range and excels over other microwave tubes in its ability to amplify a wide range of frequencies across a wide bandwidth. In addition to their commercial use in satellites and radar systems, TWT are used on certain Navy tactical jamming systems. One jamming system component, in particular, the AN/ALQ-99(V) band 9/10 transmitter contains four TWT that produce a specified radio frequency power. The four tubes must be matched in phase in order for the transmitter to function effectively, thus, each must be calibrated and tested. Prior phase-matching methods yielded a phase error which in turn can cause failure of the jamming system.
Navy researchers have developed a tube measurement and calibration system including a network analyzer for measuring tube radio frequency phase, a calibration adapter for tuning tube radio frequency power and phase, an amplifier for boosting input radio frequency power into the tube, and a rigid coaxial cable for communication between all of these components. The calibration adapter has a device of known phase length used to substitute for the measured TWT during calibration of the network analyzer.
In operation, the calibration adapter calibrates the system (specifically the network analyzer), to the specified radio frequency power. Once the network analyzer has been calibrated then the calibration adapter is disconnected from the network analyzer and a TWT is attached. The TWT is then calibrated to be matched in-phase with the calibration adapter.
- Allows for almost zero error in phase measurement due to cable flexure
- Can measure wave tubes and ensure they are matched in phase
- US patent 6,970,002 available for license