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

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

1 Answer

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 antenna. 

OR

The component of antenna resistance that accounts for the power radiated into space and is equal in ohms to the radiated power in watts divided by the square of the effective current in amperes at the point of power supply.

Antenna Gain – 

The directional antennae radiate more power in certain direction. The Omni-directional antenna radiates information equally in all directions. A directional antenna is said to have ‘gain’ in a particular direction. 

Directivity- 
The directive gain can be defined in any direction. However directivity means the maximum directive gain which is obtained in only one direction in which the radiation is maximum.

Therefore
Directivity = Maximum Directive gain

Power density-
The power density at any distance from an isotropic antenna is simply the transmitter power divided by the surface area of a sphere (4πR2) at that distance.
by

Related questions

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

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

Last 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

An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.

Description : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.

Last Answer : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.

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

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

Last 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. 

Write one application of following antenna i. Rectangular antenna ii. Dish antenna iii. Yagi-Uda antenna iv. Horn antenna

Description : Write one application of following antenna i. Rectangular antenna ii. Dish antenna iii. Yagi-Uda antenna iv. Horn antenna 

Last Answer : i. Rectangular antenna is used in direction finding in portable recievers. ii. Dish antenna is used to transmit and receive signal from satellite. iii. Yagi-Uda antenna is used in HF and VHF range as a TV receiving antenna. iv. Horn antenna is used in satellite tracking.

Draw radiation pattern for following antenna i) Yagi-Uda antenna ii) Loop antenna iii) Dish antenna iv) Horn antenna

Description : Draw radiation pattern for following antenna i) Yagi-Uda antenna ii) Loop antenna iii) Dish antenna iv) Horn antenna

Last Answer : Type of antenna Radiation Patteren  Yagi-Uda antenna Loop antenna Dish antenna Horn antenna 

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

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

Last 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-  

Compare PAM, PWM, and PPM on the basis of i. Variable characteristics ii. Bandwidth iii. Information contained in iv. Transmitted power

Description : Compare PAM, PWM, and PPM on the basis of i. Variable characteristics ii. Bandwidth iii. Information contained in iv. Transmitted power

Last Answer : Compare PAM, PWM, and PPM on the basis of i. Variable characteristics ii. Bandwidth iii. Information contained in iv. Transmitted power

a) For a transmission line, Find SWR and reflection coefficient R if, i. There is no reflected voltage. ii. Reflected voltage and incident voltage is equal. iii. If reflected voltage=20V and incident voltage=10V. iv. If reflected voltage=10V and incident voltage =20V.

Description : a) For a transmission line, Find SWR and reflection coefficient R if, i. There is no reflected voltage. ii. Reflected voltage and incident voltage is equal. iii. If reflected voltage=20V and incident voltage=10V. iv. If reflected voltage=10V and incident voltage =20V.

Last Answer : reflection coefficient R=Vr/Vi i. There is no reflected voltage. i.e,Vr=0 R=0 SWR= 1+R/1-R=1 ii. Reflected voltage and incident voltage is equal. Vr=Vi; R=1 SWR= 1+R/1-R=1+1/1-1=infinity iii. If reflected ... and incident voltage =20V. Vr=10 and Vi=20 R=10/20=0.5 SWR= 1+R/1-R=1+.5/1-.5=3 

Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application

Description : Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application

Last Answer : Compare AM and FM on the basis of i)Definition ii)Bandwidth iii) Wave propogation iv)Number of sidebands

List the types of micro-strip antennas. Explain any one of them.

Description : List the types of micro-strip antennas. Explain any one of them.

Last Answer : List the types of micro-strip antennas are as fallows. 1) RECTANGULER 2) CIRCULER. 3) SQUARE . 4) ELIPTICAL. 5) TRINGULAR. Rectangular Micro-strip Antenna: Micro-strip ... mobile phone market. Patch antennas are low cost, have a low profile and are easily fabricated. 

Compare resonant and non-resonant antennas.

Description : Compare resonant and non-resonant antennas.

Last Answer : Distinguish between resonant and non-resonant antennas.

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

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

Last 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

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

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

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

______ is the measurement of a unilateral antenna properties of directivity A. Phase angle B. Antenna gain C. Beamwidth D. Bandwidth

Description : ______ is the measurement of a unilateral antenna properties of directivity A. Phase angle B. Antenna gain C. Beamwidth D. Bandwidth

Last Answer : C. Beamwidth

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

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

Last 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.

In a FM system, the maximum deviation is 75KHz. Find bandwidth for modulating frequency i. fm=500Hz ii. fm=5KHz iii. fm=10KHz Draw conclusion for bandwidth of FM from answer.

Description : In a FM system, the maximum deviation is 75KHz. Find bandwidth for modulating frequency i. fm=500Hz ii. fm=5KHz iii. fm=10KHz Draw conclusion for bandwidth of FM from answer.

Last Answer : Given deviation∆=75kHz i) fm=500Hz bandwidth B.W=2(∆+fm)  =2(75k+500)=151kHz  ii). fm=5KHz bandwidth B.W=2(∆+fm)  =2(75k+5k)=160KHz iii) fm=10KHz bandwidth B.W=2(∆+fm)  =2(75k+10k)=170KHz As the modulating frequency increases bandwidth also increases.

Draw construction of Yagi-Uda antenna and explain.

Description : Draw construction of Yagi-Uda antenna and explain.

Last Answer : Explanation A Yagi-Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of ... receiver with a transmission line and additional parasitic elements called reflector and one or more directors.

Explain how modulation reduces height of antenna and avoid mixing of signals.

Description : Explain how modulation reduces height of antenna and avoid mixing of signals.

Last Answer : Modulation reduces antenna height: For the transmission of radio signals, the antenna height must be multiple of λ/4 ,where λ is the wavelength . λ = c /f where c : is the ... will occupy different slots in the frequency domain (different channels). Thus, modulation avoids mixing of signals.

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

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

Last 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 

Dish antenna is parabolic in shape and has meshy structure. Give reasons.

Description : Dish antenna is parabolic in shape and has meshy structure. Give reasons.

Last Answer : A Practical reflector employing the properties of the parabola will be a three dimensional bowl-shaped surface, obtained by revolving the parabola about the axis AB. The resulting geometric ... (directrix) is constant. These geometric properties yield an excellent microwave or light reflector. 

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

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

Last Answer : Half wave dipole antenna Explanation:  1. It is a resonant antenna 2. It is exact half wavelength (λ /2) long & open circuited at one end. 3. The dipole antennas have ... pattern is bidirectional.  The radiation pattern of half wave dipole antenna is - The radiation pattern

Draw Yagiuda antenna with its radiation pattern.

Description : Draw Yagiuda antenna with its radiation pattern.

Last Answer : Construction of Yagi-Uda Antenna Radiation Pattern of Yagi-Uda Antenna

Draw the structure of horn antenna and its radiation pattern. List its any two applications.

Description : Draw the structure of horn antenna and its radiation pattern. List its any two applications.

Last Answer : The structure of horn antenna Radiation pattern of Horn Antenna Application:- i) Used at microwave frequency. ii) Used in satellite tracking 

The effect of adding parasitic elements of a Hertz dipole is to A. make the antenna more omnidirectional B. reduce its resonant frequency C. increase the antenna’s power gain D. All of these

Description : The effect of adding parasitic elements of a Hertz dipole is to A. make the antenna more omnidirectional B. reduce its resonant frequency C. increase the antenna’s power gain D. All of these

Last Answer : C. increase the antenna’s power gain

Define following terms related to logic families : (i) Noise Margin (ii) FAN-OUT (iii) Propagation delay (iv) Power dissipation

Description : Define following terms related to logic families : (i) Noise Margin (ii) FAN-OUT (iii) Propagation delay (iv) Power dissipation

Last Answer : i) Noise immunity is measured in terms of noise margin. High state Noise margin = VNH = VOH(min) - VIH(min) Low state Noise margin = VNL = VIL(max) - VOL(max) i) The fan-out is defined as the ... logical 0 state (HIGH to LOW) iii) Average power dissipation is defined as PD(avg) = ICC(avg) * VCC

Define each of following terms of operational amplifiers i) Slew rate ii) Input offset voltage iii) Voltage gain iv) Input capacitance

Description : Define each of following terms of operational amplifiers i) Slew rate ii) Input offset voltage iii) Voltage gain iv) Input capacitance

Last Answer : i) Slew rate:- Maximum rate of change of o/p voltage per unit of time. It is express in volt/µsec.  ii) Input offset voltage:- The voltage that must be applied between two ... capacitance that can be measured at either be inverting or non-inverting terminal with other terminal connected to ground.

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

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

Last 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.

It is the ratio of the power density radiated in a particular direction to the power density radiated to the same point by a reference antenna, assuming both antennas are radiating the same amount of power

Description : It is the ratio of the power density radiated in a particular direction to the power density radiated to the same point by a reference antenna, assuming both antennas are radiating the same amount of power

Last Answer : directive gain

How will you increase the gain of an antenna? A. By adding several antennas in parallel B. By focusing the radiated energy in one desired direction C. By making antenna rods thicker D. By making the antenna size larger

Description : How will you increase the gain of an antenna? A. By adding several antennas in parallel B. By focusing the radiated energy in one desired direction C. By making antenna rods thicker D. By making the antenna size larger

Last Answer : B. By focusing the radiated energy in one desired direction

What is the gain of four identically polarized antennas stacked one above the other and fed in phase? A. 3 dB over the gain of one antenna B. 10 dB over the gain of one antenna C. 4 dB over the gain of one antenna D. 6 dB over the gain of one antenna

Description : What is the gain of four identically polarized antennas stacked one above the other and fed in phase? A. 3 dB over the gain of one antenna B. 10 dB over the gain of one antenna C. 4 dB over the gain of one antenna D. 6 dB over the gain of one antenna

Last Answer : D. 6 dB over the gain of one antenna

Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.

Description : Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.

Last Answer : (i) Magnetic flux density (B): It is the magnetic flux per unit area measured at right angles to the flux path. (Its unit is weber/m2 or tesla).  (ii) Reluctance: It is the ... flux to set up through it and it is reciprocal of reluctance. Permeance = 1/ Reluctance. Unit: weber/ampere.

Define the terms related to a.c. supply with waveform : i) Instantaneous value ii) Time period iii) Amplitude iv) Phase difference.

Description : Define the terms related to a.c. supply with waveform : i) Instantaneous value ii) Time period iii) Amplitude iv) Phase difference. 

Last Answer : i) Instantaneous value: The instantaneous value is the value of an alternating quantity (it may ac voltage or ac current or ac power) at a particular instant of time in the cycle .  OR  ... difference: Phase difference is the difference in phase angle between two sinusoids or phasors. 

Define the following terms related to tariff: (i) Connected load (ii) Unit consumed (iii) Fixed charges (iv) Electricity Tax

Description : Define the following terms related to tariff: (i) Connected load (ii) Unit consumed (iii) Fixed charges (iv) Electricity Tax 

Last Answer : (i) Connected load  It is the sum of the power ratings (Watts or kW or MW) of all devices and machines existing (installed) in the premises of consumer. It is used to decide the ... a percentage of the total electricity bill which includes all amounts that go to the electricity supply agency. 

Factors that determine the radiation resistance of an antenna A. Transmission line length and height of antenna B. The location of the antenna with respect to nearby objects C. It is a constant for all antennas since it is physical D. Sunspot activity and the time of day

Description : Factors that determine the radiation resistance of an antenna A. Transmission line length and height of antenna B. The location of the antenna with respect to nearby objects C. It is a constant for all antennas since it is physical D. Sunspot activity and the time of day

Last Answer : B. The location of the antenna with respect to nearby objects

Define critical frequency w.r. to wave propagation.

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

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

Define VSWR with refernce to standing waves.

Description : Define VSWR with refernce to standing waves.

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

Define sensitivity with graph.

Description : Define sensitivity with graph.

Last Answer : Define sensitivity with graph.

Define PAM, PWM, and PPM. Draw waveforms.

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

Last 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.

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

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

Last 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:

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

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

Last 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

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

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

Last 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 

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

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

Last 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.

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

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

Last 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. 

Define fading? List the causes.

Description : Define fading? List the causes.

Last 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.

Define electromagnetic wave and polarization.

Description : Define electromagnetic wave and polarization.

Last 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.

Define the term baluns and explain where is it used?

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

Last 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.

Define selectivity and sensitivity of AM Receiver.

Description : Define selectivity and sensitivity of AM Receiver. 

Last 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. 

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

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

Last 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 

Define pulse modulation. State its types.

Description : Define pulse modulation. State its types. 

Last 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 

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

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

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