What is a Travelling wave tube amplifier?
What is a Travelling wave tube amplifier?
A traveling-wave tube (TWT, pronounced “twit”) or traveling-wave tube amplifier (TWTA, pronounced “tweeta”) is a specialized vacuum tube that is used in electronics to amplify radio frequency (RF) signals in the microwave range. These function as narrowband power amplifiers.
What are the different waves possible in TWT?
Therefore, a slow-wave structure is used that causes a reduction in the phase velocity of the RF wave inside the TWT. The slow-wave structures can be of different types like a single helix, double helix, zigzag line, corrugated, coupled-cavity or ring bar type etc.
What are the two basic types of traveling-wave tubes?
A traveling-wave tube (TWT) is a specialized vacuum tube used in wireless communications, especially in satellite systems. The TWT can amplify or generate microwave signals. Two common types of TWT include the Klystron and the magnetron .
Are traveling-wave tubes still used?
While TWTs are originally used beginning at around 300 MHz, the use of TWTs for high-power applications at these lower frequencies have largely been made obsolete by SSPAs. However, as applications go into the tens of GHz, TWTs still have a major role.
What is the difference between Travelling wave tube and magnetron?
Magnetron tubes are representative of an entirely different kind of tube than the klystron. Whereas the latter tubes use a linear electron beam, the magnetron directs its electron beam in a “circular pattern” by means of a strong magnetic field.
What are the applications of Travelling wave tube?
There are many applications of a travelling wave tube. TWT is used in microwave receivers as a low noise RF amplifier. TWTs are also used in wide-band communication links and co-axial cables as repeater amplifiers or intermediate amplifiers to amplify low signals.
Why attenuator is used in TWT?
The role of the RF attenuator placed in the center portion of the slow-wave circuit is to prevent feedback oscillation in the TWT. After passing over the slow-wave circuit, the electron beam reaches the collector, and the electron energy is converted to heat and dissipated.
Why helix is used in TWT?
Helix acts as a slow wave structure. As the helix provides least change in Vp phase velocity, it is preferred over other slow wave structures for TWT. In TWT, the electron gun focuses the electron beam, in the gap between the anode plates, to the helix, which is then collected at the collector.
What is difference between klystron and TWT?
This page on TWT vs Klystron describes difference between TWT and Klystron….Klystron.
| TWT | Klystron |
|---|---|
| Interaction between EM field and beam of electrons in TWT is continuous over the entire length. | Interaction in klystron occurs only at the gaps of resonant cavities. |
Why is an attenuator used in TWT?
The role of the RF attenuator placed in the center portion of the slow-wave circuit is to prevent feedback oscillation in the TWT. The intermediate cavities enhance the electron beam modulation, then an amplified RF signal is induced at the final cavity.
What is the efficiency of TWT?
Uniform structure TWTs are usually operated such that the beam velocity is equal to or greater than the cold phase velocity in the supporting slow-wave structure. Typical efficiencies for synchronous structures are about 25%, which can be in- creased to 30-35% by use of a structure with a lower phase velocity.
What is difference between TWT and klystron?
