The radar transmitter is required to have the following technical and operating characteristics:
Construction and operation[ edit ] Conventional tube design[ edit ] In a conventional electron tube vacuum tubeelectrons are emitted from a negatively charged, heated component called the cathode and are attracted to a positively charged component called the anode.
The components are normally arranged concentrically, placed within a tubular-shaped container from which all air has been evacuated, so that the electrons can move freely hence the name "vacuum" tubes, called "valves" by the British If a third electrode is inserted between the cathode and the anode called a control gridthe flow of electrons between the cathode and Operation of twt and magnetrons can be regulated by varying the voltage on this third electrode.
This allows the resulting electron tube called a " triode " because it now has three electrodes to function as an amplifier because small variations in the electric charge applied to the control grid will result in identical variations in the much larger current of electrons flowing between the cathode and anode.
One concept used a magnetic field instead of an electrical charge to control current flow, leading to the development of the magnetron tube.
Microwave Tubes – Travelling Wave Tubes (TWTs), Magnetrons and Klystrons. At TMD we understand microwave tubes. We've been immersed in the research, design and manufacture of electron devices since their inception, delivering solutions into some of the most demanding applications, supporting our customers’ requirements. 42 · An X-band W Class High Power GaN HEMT Amplifier for Radar Applications 4. Matching Circuit Design Figure 5 shows the top view of the developed device. The unit gate width and gate periphery are µm and mm, respectively. Inspection and operation after 24 hours of salt fog exposure where buildups of salt deposits are critical to the proper operation of the test item Specify if operation of electrical system is .
In this design, the tube was made with two electrodes, typically with the cathode in the form of a metal rod in the center, and the anode as a cylinder around it.
The tube was placed between the poles of a horseshoe magnet  arranged such that the magnetic field was aligned parallel to the axis of the electrodes. With no magnetic field present, the tube operates as a diode, with electrons flowing directly from the cathode to the anode.
In the presence of the magnetic field, the electrons will experience a force at right angles to their direction of motion, according to the left-hand rule. In this case, the electrons follow a curved path between the cathode and anode.
The curvature of the path can be controlled by varying either the magnetic field, using an electromagnetor by changing the electrical potential between the electrodes.
At very high magnetic field settings the electrons are forced back onto the cathode, preventing current flow. At the opposite extreme, with no field, the electrons are free to flow straight from the cathode to the anode.
There is a point between the two extremes, the critical value or Hull cut-off magnetic field and cut-off voltagewhere the electrons just reach the anode. At fields around this point, the device operates similar to a triode. However, magnetic control, due to hysteresis and other effects, results in a slower and less faithful response to control current than electrostatic control using a control grid in a conventional triode not to mention greater weight and complexityso magnetrons saw limited use in conventional electronic designs.
Due to an effect now known as cyclotron radiationthese electrons radiate radio frequency energy. The effect is not very efficient. Eventually the electrons hit one of the electrodes, so the number in the circulating state at any given time is a small percentage of the overall current.
It was also noticed that the frequency of the radiation depends on the size of the tube, and even early examples were built that produced signals in the microwave region.
Early conventional tube systems were limited to the high frequency bands, and although very high frequency systems became widely available in the late s, the ultra high frequency and microwave regions were well beyond the ability of conventional circuits.
The magnetron was one of the few devices able to generate signals in the microwave band and it was the only one that was able to produce high power at centimeter wavelengths. Split-anode magnetron[ edit ] Split-anode magnetron from This meant that it produced very low-power signals.
Nevertheless, as one of the few devices known to create microwaves, interest in the device and potential improvements was widespread. The first major improvement was the split-anode magnetron, also known as a negative-resistance magnetron.
As the name implies, this design used an anode that was split in two—one at each end of the tube—creating two half-cylinders. When both were charged to the same voltage the system worked like the original model.
But by slightly altering the voltage of the two plates, the electron's trajectory could be modified so that they would naturally travel towards the lower voltage side.
The plates were connected to an oscillator that reversed the relative voltage of the two plates at a given frequency.One main type of transmitters is the keyed-oscillator type.
In this transmitter one stage or tube, usually a magnetron produces the rf pulse. The oscillator tube is keyed by a high-power dc pulse of energy generated by a separate unit called the leslutinsduphoenix.com transmitting system is called POT (Power Oscillator Transmitter).Radar units fitted with a POT are either non-coherent or pseudo-coherent.
Inspection and operation after 24 hours of salt fog exposure where buildups of salt deposits are critical to the proper operation of the test item Specify if operation of electrical system is . The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field while moving past a series of open metal cavities (cavity resonators).Electrons pass by the openings to these cavities and cause radio waves to oscillate within, similar to the way a whistle produces a tone .
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.
The TWT belongs to a category of "linear beam" tubes, such as the klystron, in which the radio wave is . 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.
The TWT belongs to a category of "linear beam" tubes, such as the klystron, in which the radio wave is amplified by absorbing power from a beam of electrons as it. ABSTRACT A review of TWT technology is presented comparing selected aspects and design procedures relative to application.
The general theory of operation of various types of TWT designs.