Describe line of sight propagation in brief.

Describe line of sight propagation in brief.
by

1 Answer

Answer :

Line of sight propagation or Space wave propagation:-

image 

Explanation:- Space wave propagation of electromagnetic energy includes radiated energy that travels in the lower few miles of Earth’s atmosphere. Space waves include direct and ground – reflected waves. Direct waves travel essentially in a straight line between the transmit and receive antennas. Space wave propagation with direct waves is commonly called line-of sight (LOS) transmission. Therefore, direct space wave propagation is limited by the curvature of the Earth. Ground reflected waves are waves reflected by Earth’s surface as they propagate between the transmit and receive antennas. 

by

Related questions

Describe the effect of ionosphere on sky wave propagation.

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

Last 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.  

Explain duct propagation with neat sketch.

Description : Explain duct propagation with neat sketch.

Last 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.

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.

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

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

Last 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. 

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

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

Last 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

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

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

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

Explain the transverse electromagnetic waves in wave propagation.

Description : Explain the transverse electromagnetic waves in wave propagation.

Last 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

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

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

Last 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.

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. 

Describe the functions of mixer and local oscillator in radio receiver

Description : Describe the functions of mixer and local oscillator in radio receiver

Last Answer : Frequency Mixer:- The function of frequency mixer is to heterodyne signal frequency fs and local oscillator frequency fo. At the output, it produces the difference frequency known as ... local oscillator frequency fo is then mixed with incoming frequency to give intermediate frequency. 

Describe the block diagram of FM superhetrodyne receiver

Description : Describe the block diagram of FM superhetrodyne receiver

Last Answer : RF amplifier:- There are two important functions of RF amplifier: 1) To increase the strength of weak RF signal. 2) To reject image frequency signal. In FM broadcast the ... FM broadcast, the maximum modulating frequency is 15 kHz. Hence the audio amplifier must have large bandwidth.

Describe ionosphere with neat sketch.

Description : Describe ionosphere with neat sketch.

Last 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  

Describe the block diagram of basic communication system.

Description : Describe the block diagram of basic communication system.

Last Answer : Describe the block diagram of basic communication system.

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. 

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

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

Last 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. 

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

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

Last Answer : L=0.5 mH/Km C=0.08 µF

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 : 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.

Last Answer : Solution :

Draw waveform for standing waves on an open and shorted line. Prove that impedance is inverted at every quarter wavelength interval.

Description : Draw waveform for standing waves on an open and shorted line. Prove that impedance is inverted at every quarter wavelength interval.

Last Answer : Waveform- Explanation When the transmission line is short circuited voltage is zero and current is maximum.The variation is according to the wavelength. When the ... The pattern repeats for every half wavelength. Thus impedance is inverted at every quarter wavelength interval.

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 

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:

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

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

Last 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

Draw general equivalent circuit of transmission line.

Description : Draw general equivalent circuit of transmission line.

Last Answer : Fig. General Equivalent circuit of transmission line 

The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.

Description : The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.

Last Answer : The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.

For a transmission line, the incident voltage. Ei = 6V and Er =2V ,Calculate: (i) Reflection Coefficient (ii) SWR

Description : For a transmission line, the incident voltage. Ei = 6V and Er =2V ,Calculate: (i) Reflection Coefficient (ii) SWR

Last Answer : Reflection Coefficient(K) = Er / Ei  = 2V / 6V  K = 0.333 SWR = 1+K / 1- K  = 1+0.333 / 1-0.333  = 1.333 / 0.667 SWR= 1.998

State and explain the losses in transmission line.

Description : State and explain the losses in transmission line.

Last Answer : Losses in Transmission Line:- There are three ways in which energy, applied to a transmission may desperate before reaching the load. They are 1) Radiation Losses:- Its occurs when a ... down voltage of the dielectric insulator. Generally when corona occurs, the transmission line is destroyed.

A means of beyond the line-of-sight propagation of microwave signal. A. Space wave B. Microwave link C. Troposcatter D. Point-to-point

Description : A means of beyond the line-of-sight propagation of microwave signal. A. Space wave B. Microwave link C. Troposcatter D. Point-to-point

Last Answer : C. Troposcatter

ECE Board Exam March 1996 When the transmitting and receiving antennas are in line-of-sight of each other, the mode of propagation is ________ wave. A. space or direct B. ground C. surface D. sky

Description : ECE Board Exam March 1996 When the transmitting and receiving antennas are in line-of-sight of each other, the mode of propagation is ________ wave. A. space or direct B. ground C. surface D. sky

Last Answer : A. space or direct

Signals with a frequency between 2 MHz and 30 MHz use ______ propagation. A) ground B) sky C) line-of-sight D) none of the above

Description : Signals with a frequency between 2 MHz and 30 MHz use ______ propagation. A) ground B) sky C) line-of-sight D) none of the above

Last Answer : sky

Signals with a frequency below 2 MHz use _______ propagation. A) ground B) sky C) line-of-sight D) none of the above

Description : Signals with a frequency below 2 MHz use _______ propagation. A) ground B) sky C) line-of-sight D) none of the above

Last Answer : ground

The VLF and LF bauds use .............. propagation for communication. (A) Ground (B) Sky (C) Line of sight (D) Space

Description : The VLF and LF bauds use .............. propagation for communication. (A) Ground (B) Sky (C) Line of sight (D) Space

Last Answer : Answer: A Explanation: VLF (Very Low Frequency) LF (Low Frequency) In general there are three type of propagation.1.Ground Propagation 2.Sky propagation 3.Line-of-sight propagation ... portion of the atmosphere. These low-frequency signals travel in all directions from the transmitting antenna.

Which of the following statements is not true with respect to microwaves? (A) Electromagnetic waves with frequencies from 300 GHz to 400 THz. (B) Propagation is line-of-sight. (C) Very high-frequency waves cannot penetrate walls. (D) Use of certain portions of the band requires permission from authorities.

Description : Which of the following statements is not true with respect to microwaves? (A) Electromagnetic waves with frequencies from 300 GHz to 400 THz. (B) Propagation is line-of-sight. (C) Very ... waves cannot penetrate walls. (D) Use of certain portions of the band requires permission from authorities.

Last Answer : (A) Electromagnetic waves with frequencies from 300 GHz to 400 THz.

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

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

Last 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.

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

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

Last 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.

Draw and label the circuit diagram of ratio detector

Description : Draw and label the circuit diagram of ratio detector 

Last Answer : Draw and label the circuit diagram of ratio detector  

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

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

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

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.  

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

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

Last Answer : Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy  Circuit Diagram:

A superheterodyne radio receiver with an IF of 455KHZ is turned to 1000KHZ. Find: (i) Image frequency (ii) Local oscillator frequency

Description : A superheterodyne radio receiver with an IF of 455KHZ is turned to 1000KHZ. Find: (i) Image frequency (ii) Local oscillator frequency

Last Answer : Given Intermediate Frequency fi=455KHz Signal frequency =fs=1000KHz Local oscillator frequency fo=fs+fi  Fo=1000KHz+455KHz  =1455KHz Image frequency is the input frequency which produces the same intermediate frequency fsi=fs+2fi  =1000KHz+2*455KHz  =1910KHz 

Draw circuit diagram of transistor reactance modulator. Explain its working.

Description : Draw circuit diagram of transistor reactance modulator. Explain its working.

Last Answer : Explanation- A reactance modulator is illustrated in figure. It is basically a standard commonemitter class A amplifier. Resistors R1 and R2 from a voltage divider to bias ... frequency, whereas a lower capacitance increases the frequency. The circuit produces direct frequency modulations.

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-  

State and explain the concept of transmission bandwidth.

Description : State and explain the concept of transmission bandwidth.

Last Answer : Bandwidth is defined as the portion of the electromagnetic spectrum occupied by a signal We may also define the bandwidth as the frequency range over which as information signal is transmitted. Bandwidth is the ... to 15 KHZ. Therefore the bandwidth is(f2-f1) BW= f2 - f1= 15000-20=14980Hz

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

State two disadvantages of TRF receiver over superheterodyne receiver.

Description : State two disadvantages of TRF receiver over superheterodyne receiver.

Last Answer : Disadvantages of TRF Receiver: 1. Instability due to oscillatory nature of RF amplifier. 2. Variation in bandwidth over tuning range. 3. Insufficient selectivity at high frequencies 4. Poor adjacent channel rejection capability 

Define sensitivity with graph.

Description : Define sensitivity with graph.

Last Answer : Define sensitivity with graph.

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

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

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

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

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

Last Answer : Diagram: Explanation:   Curve:  

Draw block diagram of FM receiver and explain the use of limiter circuit.

Description : Draw block diagram of FM receiver and explain the use of limiter circuit.

Last Answer : Diagram Explanation Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy.

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

Explain “BALUN” with neat sketch

Description : Explain “BALUN” with neat sketch

Last Answer : Diagram- Explaination

Explain working of envelope detector with suitable diagram and waveform.

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

Last Answer : Envelope Detector: An Envelope Detector is an electronic circuit that takes a high frequency signal as input and provides an output which is as envelopes of the original signal. The capacitor ... decreases the responsiveness thus, real-world designs must be optimized for the application.