PINNACLEProf. Bhagyashri Thorat
SPPU BE E&TCRadiation & Microwave Theory, 2019 courseमराठी + English

Radiation & Microwave Theory for SPPU E&TC

Microwave engineering is where many students lose marks, because the components are hard to picture. This is Prof. Thorat's largest playlist (41 English videos), now joined by animated 3D Shorts that show the klystron actually working.

Watch the lessonsSee all units

The subject starts with antenna fundamentals and the Friis equation, then moves into waveguides, passive components such as the E-plane, H-plane and magic tee (with their scattering matrices), and microwave tubes like the two-cavity and reflex klystron. Solid-state devices and measurement techniques complete the course.

For the scattering-matrix questions, learn the properties of each tee before memorising matrices. For tubes, understand velocity modulation and bunching once, and the reflex klystron's modes and the lab experiment follow naturally. The free revision sheet on this site summarises the reflex klystron on one page.

Syllabus

SPPU syllabus units (2019 course)

  1. Unit I: Fundamental Theory of Radiation and Radiating Elements

    Free-space propagation, Friis transmission equation, radiation mechanism and antenna types, radiation pattern, directivity, gain, efficiency, half-power beamwidth, bandwidth, polarization, input impedance, effective length and area.

  2. Unit II: Transmission Lines and Waveguides

    Microwave bands and applications, waveguides vs coaxial cable, rectangular waveguide modes, cutoff frequency, dominant mode, excitation and coupling (probe, loop, slot), re-entrant cavities, striplines.

  3. Unit III: Passive Microwave Components

    E-plane, H-plane and magic tee with scattering analysis; ferrites and Faraday rotation; isolator, circulator, directional coupler; gyrator.

  4. Unit IV: Active Microwave Components

    Limitations of conventional tubes, O-type and M-type tubes, re-entrant cavity, velocity modulation; single-cavity (reflex) and two-cavity klystron, cylindrical magnetron, helix TWT.

  5. Unit V: Solid State Microwave Devices

    Microwave transistors and MOSFET, varactor and PIN diodes, parametric amplifiers, tunnel diode, Schottky barrier diode, Gunn diode, IMPATT and TRAPATT.

  6. Unit VI: Microwave Systems and Measurement Techniques

    Terrestrial and satellite microwave links, radar range equation, industrial and medical uses; slotted line, VSWR meter, power meter; measuring S-parameters, frequency, power, attenuation, VSWR and impedance; radiation hazards.

Unit titles follow the SPPU 2019-course syllabus for Radiation and Microwave Theory. Check your college's copy for any revision.

New: animated 3D Shorts

Learn with your own eyes

The new Shorts show each concept actually working, synced to her voice in मराठी. You watch the electrons move instead of reading about them. Start with the reflex klystron series.

Live

Velocity modulation = bus stop trick

सगळे electrons एकाच speed ने जात नाहीत

You see: Electrons speed up and slow down at the buncher gap, then bunch together in the drift space.

Watch the Short (opens in new tab)
New this week

Why do electrons come back in a reflex klystron?

Electrons परत का येतात?

You see: The negative repeller slows an electron to zero and sends it back through the same cavity.

Find it on the Shorts tab (opens in new tab)
New this week

Reflex klystron experiment: how the graph appears

Graph कसा येतो?

You see: Turn the repeller knob and watch the power and frequency graphs draw themselves.

Find it on the Shorts tab (opens in new tab)
New this week

Two-cavity vs reflex klystron

Exam मध्ये हमखास येणारा प्रश्न

You see: A relay race for the two-cavity tube and a boomerang for the reflex tube, side by side.

Find it on the Shorts tab (opens in new tab)
All Shorts on YouTube (opens in new tab) Klystron revision PDF

Free lessons

Videos for this subject

Tap to play here.

फ्रिस समीकरण : अँटेना पॉवर आणि गेनसाठी चरण-दर-चरण मार्गदर्शन

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L4 :मॅजिक टी आणि स्कॅटरिंग मॅट्रिक्स | वैशिष्ट्ये | मायक्रोवेव्ह अभियांत्रिकी |

Watch on YouTube (opens in new tab)

Full playlists

Structured course

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MicrowaveEnglish

SPPU Microwave Engineering: PYQ Solved & Numericals

Exam-focused microwave engineering: waveguides, E-plane, H-plane and magic tees with scattering matrices, network parameters, antennas and arrays, plus a test-bench demo.

  • Microwave frequencies, devices and transmission
  • E-plane, H-plane and magic tee with S-matrix
  • H, Y, Z, ABCD and scattering parameters
  • Solved numericals
  • Antennas, arrays and the microwave test bench

5.0 (1 rating) on Udemy

22 lectures · 2h 27m · 4 students · updated 5/2026

View on Udemy (opens in new tab)

FAQ

Questions students ask

Why can't we use Z, Y or ABCD parameters at microwave frequencies?
Those parameters need ideal open or short circuits at the ports, which are hard to create at microwave frequencies and can make active devices unstable. Scattering (S) parameters use matched loads and measure incident and reflected waves, so they can be measured reliably.
Why is a reflex klystron an oscillator?
It has only one cavity, which works as both buncher and catcher. The negative repeller sends the electrons back through the same cavity, so energy is fed back and the tube sustains oscillations when the transit time satisfies T′ = (n + ¾)T.
What is the maximum efficiency of a reflex klystron?
The theoretical maximum is about 22.78 %, compared with about 58 % for a two-cavity klystron. Practical efficiencies are lower.
Which graphs do I draw in the reflex klystron experiment?
Keep the beam voltage fixed, vary the repeller voltage, and plot power vs repeller voltage and frequency vs repeller voltage. The power appears in separate modes, and the frequency shift inside a mode is electronic tuning.
Are there Marathi videos for microwave?
Yes, there is a Microwave (Marathi) playlist and the animated klystron Shorts are in Marathi.

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