{"id":93,"date":"2022-12-07T09:41:29","date_gmt":"2022-12-07T09:41:29","guid":{"rendered":"https:\/\/projectsgeek.com\/seminars\/?p=93"},"modified":"2022-12-09T10:37:07","modified_gmt":"2022-12-09T10:37:07","slug":"microwave-tubes-seminar-presentation","status":"publish","type":"post","link":"https:\/\/projectsgeek.com\/seminars\/microwave-tubes-seminar-presentation\/","title":{"rendered":"Microwave Tubes Seminar Presentation"},"content":{"rendered":"

Microwave Tubes<\/strong><\/h1>\n

Microwave Tubes Intro<\/strong><\/h2>\n

The microwave tubes use a Klystron amplifier that can magnify microwave signals by velocity modulation. Therefore, it forms high-velocity electrons with 30-45% efficiency reaching a max of 75% (0.5-6.4GHz). There is also Reflex Klystron for low power and low microwave oscillator efficiency. It has 4-200GHz, <10% efficiency, and TYP Po=100mW capacity. In contrast, the magnetron is a diode that uses magnetic and electric fields. It happens in a complex cavity to provide oscillations. Types include hole and slot, vane, rising sun, and coaxial. These have 10mW – UHF, 2mW – X-Band, 80KW – 95GHz, and 50-60% efficiency.<\/p>\n

\"Microwave<\/a><\/p>\n

What are microwave tubes?<\/strong><\/h2>\n

The types of microwave tubes include the traveling wave tube, cross-field amplifier, and backward wave oscillator. For the traveling tube, the beam and the RF field interact continuously. It can be used as a low-level, low-noise amplifier or high-power (CW or pulsed). The cross-field amplifier (CFA) is a cross between the TWT and Magnetron. Thus, the pulsed capacity is 1-18GHz, 5mW – UHF, 70%, 1mW – X-Band, 55%. However, the backward wave oscillator has a shorter and thicker TWT, 1 – 1000GHz microwave CW oscillator.<\/p>\n

Semiconductor Microwave Devices<\/strong><\/h2>\n

These include a transistor, a Parametric amplifier, and a Gunn diode. The transistor has 2-4GHz, 9W, 12-8dB, and 29.5-32.5db at 4-6GHz, and 15mW. FET – G=10dB, 9-15GHz, and F=7-14dB are other values. In contrast, the parametric amplifier uses a varying reactance device to result in amplification. The Gunn Diode uses the principle of the transferred electron effect. It is made of GaAs and InP. Other devices include Impact Avalanche & Transit Time Diode and Trapped Plasma Avalanche Triggered Transit Time Diode. Moreover, there are also the Tunnel, Varactor, Schottky Barrier, and PIN.<\/p>\n

What is Waveguide?<\/strong><\/h2>\n

It is a hollow metallic tube to propagate signals commonly from the 3-100GHz band. The Waveguide can transmit multiple signals using the same frequency but in different modes. Advantages of this tech include easier fabrication compared to a coaxial line, no flashover, better power handling, and lower power loss. Also, it has a higher operating frequency. Types include rectangular Waveguides with transverse electric with H-mode or transverse magnetic E-mode. The Dominant Mode has two types, mode yielding the longest cut-off wavelength and Circular Waveguide. The Circular Waveguide has a bigger cross-section and the possibility of the plane of polarization rotating due to roughness. It is easier to produce and join.<\/p>\n

Other microwave devices are Ridged Waveguides and Flexible Waveguides. There is a single or double ridge type to lower the value of cut-off wavelength for Ridged Waveguide. It decreases the guide’s size, increasing the useful frequency range and reducing phase velocity. But it has a higher loss compared to an ordinary rectangular waveguide. Flexible Waveguides can be twisted, bent, or stretched, need no joins, and have almost the same power. Flange, Taper & Twist Sections, and Junctions are also microwave devices. Matching Sections include Iris, tuning screw, slide screw, Attenuator, slotted line, SWR meter, Isolator, Circulator, and Point Contact Diode.<\/p>\n

Solving the Problem<\/strong><\/h2>\n

The common one is finding the cut-off wavelength for the dominant mode in the rectangular Waveguide. It has a breadth of 10cm and a propagated signal of 2.5GHz. You must calculate the Guide Wavelength, the group, phase velocities, and characteristic wave impedance. Also, it is vital to reproduce a 10GHz signal in a Guide. The Guide’s wall separation is 6cm. So, find out the greatest number of Halfwaves of electric field intensity. For establishing between the two walls.<\/p>\n

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