ISRO Interview Questions ECE | Crack ISRO Interview

ISRO Interview Question Collection

All ISRO Interview Questions in One Place

In this post we are sharing interview questions asked in ISRO interview.  We have collected these questions from personal experiences of candidates, social networking sites like Facebook, quora etc. We hope these questions will give you great idea about ISRO interview process. Also, we would like to tell you that in the below question list some of the questions are asked based on candidates individual skill set. So It is not desirable to know every  topic mentioned in below questions. But to be in safe side please try to cover as much topics as you can cover. This will surely increase your chances to be selected in the interview.


ISRO  Interview Details

  • Panel may consists of 5-10  senior scientists, IIT faculties etc.
  • They may ask you to choose your top 3-5 favourite questions.
  • They may mask ask questions from your favourite subjects or may not.
  • You need to give full explanation of every question/topic asked.
  • Be familiarized with Blackboard teaching as you may have explain on blackboard.
  • They may ask you about your B.Tech final year project. But It completely depends on them.
  • For M.Tech students prepare well the M.Tech thesis topic.
  • Reach interview venue before time.
  • Check all documents, a day in advance.
  • Don’t forget to keep a pen with you in interview room.


ISRO Interview Questions

  • What are maxwell’s equations? Write corresponding laws.
  • What is intrinsic impedance? Write expression for it.
  • You have an isotropic radiator. Intrinsic impedance of medium is known to you. Transmitted power is also known. How would you find out amplitude of electric field at a particular distance. Show what equations you will use.
  • What do you mean by a parallel polarized wave?

  • Do you know different frequencies used for different applications? At what frequencies waveguide is used? Why we cannot use waveguide at low frequencies?
  • What is mobility? Differentiate between drift and diffusioin.
  • How would you define electron and hole? What is the difference? Which has higher mobility, BJT or MOSFET?
  • Which has higher switching speed, BJT or Mosfet?
  • What do you mean by thermal runaway? How can we avoid it?
  • What is LED? What is difference between LED and normal diode? What is material used for LED? Why?
  • What is GMSK? Draw the Transmitter and Receiver section (Block diagram).
  • What is analog signal, discrete signal and Digital signal.
  • What are different modulations Techniques?
    Draw the constellation diagrams for BPSK, QPSK ,8PSK and 16QAM. Compare the error performance.
  • For the same transmitted power, which is better BPSK,DPSK??
  • Advantage of DPSK over BPSK
  • Bit rate and Baud rate. Give example

  • Steps in Sampling a continuous time signal? Explain
  • What is meant by Quantisation?
  • What is Sample and Hold circuit?
  • What exactly mean by RMS value (Root mean Squared )? (Physical significance not the formula)
  • Design Directional coupler using Isolator and Circulator.
  • Title of your Major project?
  • What was the output of a Band limited LPF with bandwidth “W”, when an arbitrary signal is passed through it.(Draw the output signal).
  • What are the different kind of digital modulation techniques.
  • how many types of tx line you know?
  • Draw cross section of coaxial and microstrip line?
  • Draw field line of E and H inside the guide?
  • modes of wave in strip line.
  • Draw radiation pattern of microstrip line?
  • Suppose fringing is not there then how will be the field?
  • Write expression of Zo for coaxial cable. Explain each term.
  • What is array factor?
  • What is the radiation resistance of strip?
  • Example of aperature antenna?


  • Does microstrip antenna has any gain? how it’s directivity can be increased?
  • Radiation pattern of half wave dipole and draw it.
  • Draw radiation pattern of a half wave dipole and a strip when they are together to make a combined antenna? can strip line be used? What are its disadvantages?
  • What is helical antenna? what is the use of it?
  • What is wire antenna?
  • What is stability?
  • Write transfer function of a second order system. Draw the response curve when step input is given and show peak time, mp, settling time etc on the graph.
  • What is delay time? will the system  settled down or not.
  • how many types of electronics device u know
  • Difference between pn and pin diode,  draw of I v curve explain.
  • Why pin is faster? Apart from switch what purpose pin can be used?
  • DFT and its significance.

  • FFT and its advantages along with the order of complexity in both DFT and FFT.
  • Spectral leakage and its preventions in FFT.
  • Concepts of Energy harvesting and RF energy, and Renewable energy sources.
  • PN sequence and its properties along with its applications.
  • CDMA and in which technology it is used, length of spreading in CDMA which is used in mobile communication.
  • What are filters and its uses in communication?
  • Matched filter and its significance along with its limitations.
  • Concepts of convolution and correlation.
  • Various types of noise
  • Normal distribution, Laplace equation.
  • Stoke’s theorem
  • Intrinsic impedance, impedance of free space, definition of permeability and its units etc.
  • What is CDMA,GSM,FDMA and why CDMA not being used.
  • what is noise and various types of channels
  • What is bridge rectifier and its uses compared to others , ripple frequency,  circuit diagrams, PIV etc.
  • What is noise margin and why it’s used. Noise margin of cmos.
  • If a high power CMOS is used then how can be its noise margin levels compared to low power CMOS levels.
  • difference between led and pin diode, Solar and photovoltaic cell.
  • What is dual port memory.
  • Explain DMA controller
  • What is smps and why it’s used in CPUs.


  • Glow a bulb when 0 is given. NOT gate doesn’t have good current driving capability.
  • draw and explain Ic vs Vce curve and Ib vs Vbe curve for BJT.
  • What is Early voltage?
  • Write a vhdl programme for n bit multiplier.
  • Draw output and transfer characteristics for Depletion and Enhancement MOSFET.
  • Comparison of MOSFET and BJT in application of amplifier.
  • what are the different modulation scheme for digital communication.
  • Bit error rate comparison among BPSK, QPSK and M-ary modulation scheme.
  • Shannon’s law
  • What are FIR and IIR filter?
  • If you are asked to design a filter for a specific system, you will go for FIR or IIR filter?
  • Linear phase criteria of FIR filter.
  • How will you go for high speed circuit from transition level design?
  • Explain E vs K diagram of GaAs.
  • Application of GaAs in microwave circuit.
  • What is polarization and what are its different type ?
  • In satellite communication which type of polarization is used?which type of antennas are used 
  • How can you generate ideal noise in digital circuit?
  • How can you design a noise source in analog circuit?
  • Advantages of satellite communication.


  • What is delay in LEO, MEO, GEO (low earth orbit, medium earth orbit , geostationary orbit).
  • Frequency bands used in satellite communication
  • C , K, Ku  and their ranges.
  • What is uplink /downlink convention? Why uplink frequency greater than downlink?
  • Relation between antenna gain and frequency
  • Why ku band is used these days?
  • Can low earth orbit satellites be used for communications?
  • Why signal strength is less at receiver?
  • What is Ethernet? Other name for it…802.3….other protocols of this sort? 802.4,5,11
  • What is collision detection?
  • How data is transmitted in Ethernet?
  • . Why coding techniques are used? Channel codes names only. What are different coding techniques used?
  • What are online ups and offline ups? First what is UPS?
  • How does ups work?
  • Why do we need ac and dc conversion?
  • 5 differences between an open loop system and closed loop system
  • Elaborate the differences between TDMA,FDMA and CDMA in a practical manner.
  • Definition of Lossless channel, Random channel and Deterministic channel.
  • Huffman coding basics and significance in data compression.
  • Does the mass of satellite has any impact on it’s velocity or not.
  • Triac, IGBT, Power Mosfet, SCR, SCS and Snubber circuits.
  • Differences between PD, APD and PIN diode.
  • What is FPGA?
  • Which is the fastest logic family and why?
  • Why CMOS is used more in practical applications?
  • Difference between DTL and DCTL?
  • Explain SRAM and DRAM.
  • What is Digital signal processing? why DSP is used?
  • Design straight line equation y=mx+C with an op-amp?
  • Explain Slew rate, CMRR, gain bandwidth product.
  • Difference between TRAP,RST5.5,RST6.5 and RST7.5?
  • Difference between EPROM and EEPROM?
  • Draw a timing waveform through a D flip flop and indicate setup time, hold time and propagation delay in it?
  • Working of Master-slave FF
  • Direct band gap semiconductor.
  • Types of capacitors?
  • B-H curve of transformer used in flyback and forward converter?
  • Response of buck converter on capacitive load?
  • Gate driver for high input capacitive mosfet?
  • Mosfet specifications for high side and low side mosfet in synch buck converter?
  • EMI in any converter.
  • Use of transformer? why AC is more popular over DC?
  • Bode plot and peak current mode control of sync buck converter?
  • Fourier transform and LPF based question.
  • Ehat are the points of consideration to choose any converter? like efficiency, size, regulation etc
  • Effect of temperature on core of transformer?
  • Multiple output converter basics.
  • Resonance in any electrical circuit?
  • Helmholtz equation 
  • curl and physical significance 
  • divergence and physical significance 
  • Magnetic vector potential and physical significance .
  • Design magic tee 
  • s parameters and why s parameters are used ? 
  • To calculate S11 , what to do with port 2 ?
  • QPSK , ASK and their constellation diagram


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