Define electromagnetic wave and polarization.

Define electromagnetic wave and polarization.

Electromagnetic wave:-An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular; by convention

Polarization:-polarization" of electromagnetic waves refers to the direction of the electric field.

Related questions

Description : State the types of electromagnetic polarization? Define any one of it.

Answer : Transverse electromagnetic wave:- The polarization of a plane EM wave is simply the orientation of the electric field vector with respect to the surface (i.e. looking at the horizon) If ... the field strength varies with change in polarization the wave is said to have an elliptical polarization

Description : What is electromagnetic polarization.

Answer : The polarization of a plane EM wave is simply the orientation of the electric field vector with respect to the surface (i.e. looking at the horizon)

Description : Define the following terms: (i) Polarization (ii) Antenna gain (iii)Antenna resistance (iv)Directivity

Answer : i) Polarization:- It is defined as the direction of electric field vector in the EM wave radiated by the transmitting antenna. ii) Antenna Gain:- Antenna gain is defined as the ratio of ... in only one direction in which the radiation is maximum. That is directivity = Max. directive gain

Description : Why electromagnetic waves are said to be transverse wave ? Explain.

Answer : The electromagnetic waves are oscillations which propagate through free space. In electromagnetic waves the direction of electric field, magnetic field & propagation are mutually perpendicular. Hence electromagnetic waves are called as transverse wave.

Description : Explain the transverse electromagnetic waves in wave propagation.

Answer : 1. The electromagnetic waves are oscillations, which propagate through free space. 2. Em wave travel in free space at the speed of light. 3. Figure shows the simple EM wave, in which the direction of ... electromagnetic waves (TEM). Diagram:- Transverse electromagnetic wave(TEM) OR

Description : Describe with respect to antenna (i) radiation pattern (ii) directive gain (iii) power gam (iv) polarization

Answer : (i) Radiation pattern:-A graph or diagram which tells us about the manner in which an antenna radiates more power in different directions is known as the radiation patteren of antenna.  ( ... as the direction of the electric vector in the electromagnetic wave radiated by the transmitting antenna.

Description : Define critical frequency w.r. to wave propagation.

Answer : Define critical frequency w.r. to wave propagation.

Description : Define standing wave ratio.

Answer : Standing wave ratio is defined as the ratio of maximum voltage (Vmax) to minimum voltage (Vmin). Standing wave ratio is also defined as the ratio of maximum current (Imax) to minimum current (Imin).

Description : Show that AM wave consist of two side bands and carrier. Also prove the bandwidth of AM is double of the modulating frequency.

Description : Compare ground wave propagation. Sky wave propagation and space wave propagation.

Answer : Sr. N o Parameter Ground Wave Propagation Sky Wave Propagation Space wave Propagation 1 Frequency Range 30 kHz to 3 MHz  3 MHz to 30 MHz frequencies above 30 MHz 2 ... These waves have line of sight propagation, ... 6 Fading Problem less Severe Less

Description : Describe the term virtual height with the help of diagram showing ionized layer and the path of wave.

Answer : Virtual height: -The incident wave returns back to the earth due to refraction. In this process it bends down gradually and not sharply, but the incident and reflected rays follow exactly ... . It is also defined as the maximum height that the hypothetical reflected wave would have reached.

Description : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.

Answer : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.

Description : For transmission line, the incident voltage Ei = 6V, and Er = 3V. Calculate: (1) Reflection coefficient (2) Standing wave ratio

Answer : (1)Reflection coefficient  (2) Standing wave ratio (1)Reflection coefficient Reflection coefficient R=Er/Ei  =3/6  R=0.5 (2) Standing wave ratio SWR=Ei+Er/Ei-Er  =6+3/6-3  SWR =3

Description : List and explain the properties of quarter wave transformer.

Answer : Properties of quarter wave transformer: 1. Impedance transfomation: it provides impedance transformation upto the highest frequencies and is compatible with transmission line. 2. Impedance inversion: if ZL is ... or step up transformer,depending on whether ZL IS greater than or less than ZO.

Description : A load of 200 ohm is used to match 300 ohm transmission line to achieve SWR=1. Find out the required characteristic impedance of a quarter of a quarter wave transformer connected directly to the load.

Description : Explain virtual height with respect to wave propagation with neat sketch.

Answer : In ionization layer the incident wave refracts and bends down gradually than sharply.   The incident and refracted rays follow paths that are exactly the same as they would have been if reflection had taken place from a surface located at a greater height called virtual height of this layer.

Description : Explain ground wave propogation with neat sketch.

Answer : Sketch-   Explanationi) It consists of direct wave which travels near the ground from Transmitter to Receiver. ii) The electromagnetic wave leaves the transmitting antenna & remains close to earth surface ... . The ground wave is the path chosen when frequency in between 30 KHz & 3 MHz

Description : How quarter wave transformer is used for impedance matching.

Answer : In all applications of transmission line, it is required that the load be matched to line, Which requires tuning out the unwanted load reactance and the transformation of resulting impedance to the required value ... Step down transformer If ZL <Zo then it acts as a Step up transformer

Description : Describe the effect of ionosphere on sky wave propagation.

Answer : The Ionosphere is the upper portion of the atmosphere. The ultra violet radiation from the sun will ionize the upper layer of the atmosphere. In this layer free electrons and positive and negative ions are ... layer. Its Frequency Range is from 3 MHz to 30 MHz Polarization: Vertical.

Description : Draw the radiation pattern for Dipole antenna: (i) Half wave dipole (ii) Folded dipole.

Answer : The radiation pattern for Half wave dipole antenna The radiation pattern for Folded dipole antenna.

Description : Explain the following in wave propagation: 1) Actual height 2) Virtual height

Answer : 1) Actual height:- The height attained by the wave during propagation through the ionosphere is known as Actual height. 2)Virtual height: -The incident wave returns back to the earth due to ... It is also defined as the maximum height that the hypothetical reflected wave would have reached.

Description : Define and explain the term beam width related to antenna with a sketch.

Answer : Definition: The beam width of an antenna is described as the angles created by comparing the half power point (3dB) on the main radiation lobe to its maximum power point. As an example the beam width ... max voltage at center of lobe (these point are known as half power points.) Sketch-

Description : Define PAM, PWM, and PPM. Draw waveforms.

Answer : Pulse amplitude modulation is defined as a process of varying the amplitude of the carrier pulse in accordance to the modulating signal variations. Pulse width modulation is defined as a ... of varying the position of the carrier pulse, in accordance to the modulating signal variations.

Description : Define stub. Explain single and double stub in brief with neat sketch.

Answer : Stub:- Stub is the piece of short circuited transmission line which is used to tune out the reactance of the load when connected across the transmission line as close as possible ... but lengths are independently adjustable. The double stub matching provides wide range of impedance matching.

Description : Define the term baluns and explain where is it used?

Answer : A type of electrical transformer used to connect an unbalanced circuit to a balanced oneORA balun is a type of transformer: it's used to convert an unbalanced signal to a balanced ... :- In audio applications, baluns convert between high-impedance unbalanced and low impedance balanced lines.

Description : Define selectivity and sensitivity of AM Receiver.

Answer : Selectivity:-It needs to accept signals of the wanted frequency and reject other unwanted frequencies. Sensitivity:-The sensitivity of a radio receiver is its ability to amplify weak signals. It is ... the receiver input terminals to give a standard output power, measured at the output terminals.

Description : Define: (i) Image frequency and (ii) Double spotting

Answer : i)Image frequency:- Image Frequency is defined as the signal frequency plus twice the intermediate frequency. It is denoted as fsi = fs+2fi Where, fs = Signal Frequency fi =intermediate frequency ... It is due to the poor front end selectivity i.e., inadequate image frequency rejection.

Description : Define modulation index in AM and give its formula.

Answer : In AM wave, the modulation index (m) is defined as the ratio of the amplitude of the modulating signal (Vm ) to the amplitude of carrier signal (Vc). m = Vm / Vc

Description : Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density

Answer : Antenna Resistance - The resistance of an antenna has two components: 1. Its radiation resistance due to conversion of power into electromagnetic waves 2. The resistance due to actual losses in the ... the transmitter power divided by the surface area of a sphere (4πR2) at that distance.

Description : Define VSWR with refernce to standing waves.

Answer : Voltage Standing Wave Ratio: The voltage standing wave ratio (VSWR) is the ratio of max voltage to min voltage. VSWR= VMAX /VMIN

Description : Define sensitivity with graph.

Answer : Define sensitivity with graph.

Description : Define the transmission line? Draw it‟s general equivalent circuit.

Answer : Transmission line: A conductor or conductors designed to carry electricity or an electrical signal over large distances with minimum losses and distortion.  Equivalent circuit:

Description : Define: 1)Frequency 2)Bandwidth 3)Wavelength 4)Time period

Answer : Frequency: Frequency is the number of cycles per second. Bandwidth: A range of frequencies within a given band, in particular that used for transmitting a signal. Wavelength: Wavelength can be defined as ... for one complete cycle of vibration to pass a given point.  OR Time period=1/frequency

Description : Define modulation? State the desirable value of modulation index of AM.

Answer : Modulation: It is the process in which any of these Parameters (Amplitude, Frequency, Phase) of high frequency signal (carrier signal) are varied in accordance with low frequency signal(modulating signal) For an AM, modulation index range is 0 to 1.

Description : Define fading? List the causes.

Answer : The fluctuation in signal strength at a receiver, which is mainly due to the interference of two waves which left the same source but arrived at the destination by different paths, is known ... , such as irrigation, or from multiple transmission paths, irregular earth surfaces, and varying terrains.

Description : Define pre-emphasis. State its need. Draw the circuit of pre-emphasis.

Answer : Definition- The artificial boosting of higher modulating frequencies to reduce the effect of noise is called as pre-emphasis. Need:- The artificial boosting of higher audio modulating ... by increasing the amplitude of modulating signal at higher frequencies. Circuit diagram

Description : Define pulse modulation. State its types.

Answer : Pulse Modulation - consists essentially of sampling analog information signals and then converting those samples into discrete pulses. OR It consists essentially of sampling analog information signals and then converting those ... PAM - PWM - PPM  ii) Digital Pulse Modulation - PCM - DM - ADM

Description : Define modulation index in FM. What is maximum value of deviation ratio.

Answer : Modulation Index of FM: It is defined as the ratio of Frequency Deviation (δ) to the modulating signal frequency (fm). (OR)

Description : Define the terms: 1) Maximum usable frequency 2) Fading

Answer : 1)Maximum usable frequency:- Maximum usable frequency is defined as the limiting frequency ,when the angle of incidence is other than the normal . OR The highest frequency that can be used for sky ... which left the same source but arrived at the destination by different paths is known as fading.

Description : Define: Base band signal with one example.

Answer : The electrical equivalent of the original information signal is known as the Baseband signal. Example:-The information or the input signal to a communication system can be analog i.e., sound, picture or it can be digital e.g. the computer data.

Description : Diffraction and interference demonstrate which of the following? w) particle nature of light x) wave nature of light y) polarization of light z) refraction of light

Description : Compare sky wave and space wave propagation w.r.t. following points. (i) Frequency range (ii) Effect of fading (iii)Polarization (iv)Application

Answer : Sr. No  Parameters Sky Wave Propagation Space Wave Propagation 1 Frequency range 3 MHz to 30 MHz  Above 30 MHz 2 Effect of fading Problem of fading is ... horizontally Polarized 4 Application RadioBroadcasting (SW Range) Used for TV and FM broadcasting

Description : Which of the following phenomena suggest that light may be a transverse wave? w) reflection x) polarization y) photoelectric effect z) diffraction

Answer : The polarization required in ground wave propagation is vertical (linear).

Description : A feedback amplifier has a gain of 1000 without feedback. Find the gain with feedback and the amount of feedback in dB for a negative feedback of 10%.

Description : Draw practical set-up and explain the procedure to measure selectivity of radio receiver.

Answer : Procedure to measure selectivity of radio receiver: Throughout the measurement the receiver is kept tuned to desired frequency 950 Khz. Now the generator output frequency is deviated below ... the generator output voltage is adjusted to get a standard 50 miliwatt receiver output power.

Description : Draw and label the circuit diagram of ratio detector

Answer : Draw and label the circuit diagram of ratio detector

Description : Draw the structure and state applications of: i) Ferrite loop (rod) antenna ii) Horn antenna

Answer : Horn antenna: Application:- i) Used at microwave frequency. ii) Used in satellite tracking.  Ferrite loop antenna: Application:- In Am radio receiver to receive MW and SW band signals. In FM radio receiver

Description : Calculate the characteristics impedance for a transmission line having L=0.5 mH/Km, C=0.08 µF and negligible R and G.

Answer : L=0.5 mH/Km C=0.08 µF

Description : State the need of stub. Explain single stub and double stub matching.

Answer : Stub:- Stub is the piece of short circuited transmission line which is used to tune out the reactance of the load when connected across the transmission line as close as possible. ... but lengths are independently adjustable. The double stub matching provides wide range of impedance matching.

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