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

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

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

Single stub:- Stub is the piece of short circuited TL which is used to tune out the reactance of the load when connected across the TL as close as possible.

The most important feature of single stub matching is that the stub should be located as near to the load as possible. The characteristic admittance of the stub so connected in shunt should be same as that of the main line. The main element of this transmission line is a short circuited section of line whose open end is connected to the main line at a particular distance from the load end. Where the input conductance at that point is equal to the characteristic conductance of the line, and the stub length is adjusted to provide a susceptance equal in value but opposite in sign, to the input susceptance of the main line at that point. So the total susceptance of the main line at that point is zero.  The combination of stub and the line will thus present a conductance which is equal to the characteristic impedance of the line, i.e. the main length of the HF transmission line will be matched

Double stub:- The disadvantages of single stub matching are overcome by using double stub matching as shown in fig.

Here, two short circuited stubs at two fixed point usually λ/4 apart are utilized. Their positions are fixed but lengths are independently adjustable. The double stub matching provides wide range of impedance matching.

## Related questions

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.

Description : Differentiate between single stub and double stub

Answer : Differentiate between single stub and double stub

Description : What is stub? What do you mean by single stub matching.

Answer : Stub is a 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. Single Stub Matching : ... The single stub match is perhaps the most widely used matching circuit and can match any load.

Description : Explain loop antenna with neat sketch. Draw radiation pattern. State its advantages and applications.

Answer : Loop antenna:-The single turn coil carrying RF current through it having length less than the wavelength.   Advantages:- 1. highly directive 2. Small size Applications:- 1. For direction finding 2. In portable receivers 3. In navigation

Description : Explain duct propagation with neat sketch.

Answer : Duct propagation is a special type and used for very high microwave frequencies. New phenomenon which occurs in super-refraction, also known as ducting. As the height above earth increases, ... in the standard atmosphere. The Duct propagation is used for very high frequencies in GHz range.

Description : Explain “BALUN” with neat sketch

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 isotropic radiator with neat sketch.

Answer : An isotropic radiator is a point source that radiates equally in all the directions. It is a hypothetical antenna used as a reference to describe real antenna. The radiation is represented by a sphere with center coincides with location of isotropic radiator.

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

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Description : Describe ionosphere with neat sketch.

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. Due to ionization these part of the atmosphere becom3es ... electron density of all layers, due to this F2 layer remains present at night time

Description : Explain skip zone and skip distance with neat diagram.

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Description : Explain with a neat diagram of ratio detector. Why limiter stage is not used before ratio detector.

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Description : With the help of neat diagram, explain the working of phase discriminator.

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Description : Explain effect of 'm' on AM with neat waveforms.

Answer : i)m< 1  If m < 1 or if the percentage of modulation is less than 100% the this type of modulation is known as under modulation The amplitude of modulating signal less than carrier ... greater amplitude part of its information is lost in the process of modulation which is undesirable.

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 : Enlist different types of traffic island and explain any one in brief with neat sketch.

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Description : Describe line of sight propagation in brief.

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Description : State the need of AGC. List the different types of AGC with neat graph.

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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 : Draw a neat sketch of ‘Locomotive coupler’ mechanism. Explain its working in brief.

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Description : Explain single phasing preventer with neat sketch diagram.

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Description : Define VSWR with refernce to standing waves.

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Description : Define sensitivity with graph.

Answer : Define sensitivity with graph.

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 : Describe in brief with neat sketch: i) English bond ii) Flemish bond

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Description : Describe in brief with neat sketch: i) Base line ii) Check line

Answer : i) Base line:  Base line is generally the longest line running roughly through the middle of the area. It is laid on a level ground as far as possible. The whole frame work is built upon this line. ... on the opposite side or a line joining some fixed point on any two sides of the triangle.

Description : Describe in brief with neat sketch construction of tunnel with needle beam method

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Description : Describe in brief caisson foundation for a bridge with neat sketch

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Description : Describe in brief working of Symons rain gauge with neat labelled sketch.

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Description : Compare between simplex and full duplex communication on the basis of: 1) Definition 2) Sketch

Answer : Compare between simplex and full duplex communication on the basis of: 1) Definition 2) Sketch

Description : Explain working of envelope detector with suitable diagram and waveform.

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Description : Explain standing waves with load terminal open circuited and short circuited.

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Description : Draw a neat sketch of moving primary fixed secondary double sided LIM. Write one advantage and one disadvantage of it.

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Description : Define lime and explain manufacturing of lime by continuous kiln with neat sketch.

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Description : Explain the working of amplitude limiter in FM receiver with circuit diagram.

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Description : Explain operation of balanced slope detector with „s‟ curve.

Description : Explain with block diagram of Armstrong method of FM generation.

Answer : Explanation:- The crystal oscillator generates the carrier at low frequency typically at 1 MHz this is applied to the combining network and a 90o phase shifter. The modulating signal is passed through an ... power amplifier to raise the power level of the FM signal.  Phasor Diagram:-

Description : Explain half dipole antenna ( Resonant antenna ) with its radiation patteren.

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Description : Define plant layout. Explain in detail 'Process layout' with neat sketch.

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Description : Define shoring. Enlist types of shoring. Explain any one type with neat sketch.

Answer : Shoring:- Shoring is the construction of a temporary structure to support temporarily an unsafe structure. These support walls laterally. Shoring can be used when walls bulge out, when walls crack due to ... of the structure above and transfer same to the ground on firm foundation below.

Description : Define stress concentration. Explain any four methods to reduce it with neat sketch.

Answer : ) The Standard cross section for a flat key, which is fitted on a 50mm diameter shaft, is 16×10mm. The  key is transmitting 475 Nm torque from the shaft to the hub. The key is made of commercial steel  (Syt=Syc=230 N/mm2). Determine the length of the key, if the factor of safety is 3.

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 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 electromagnetic wave and polarization.

Answer : 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.

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 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 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 critical frequency w.r. to wave propagation.

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

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