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प्रश्न
Describe briefly, by drawing suitable diagram, the space wave modes of propagation. Mention the frequency range of the waves in these modes of propagation ?
उत्तर
A space wave travels in straight line from a transmitting antenna to a receiving antenna. They are used for transmitting frequency signals above 40 MHz. Space waves are used for line of sight communication as well as satellite communication. The propagation of signal through space wave is shown below:
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संबंधित प्रश्न
(i) Which mode of propagation is used by shortwave broadcast services having frequency range from a few MHz upto 30 MHz? Explain diagrammatically how long distance communication can be achieved by this mode.
(ii) Why is there an upper limit to frequency of waves used in this mode?
What is space wave propagation?
What is ground wave communication?
Explain why ground wave communication mode cannot be used for long-distance communication using high frequencies
Is it necessary for a transmitting antenna to be at the same height as that of receiving antenna for LOS communication ?
In sky wave mode of propagation, why is the frequency range of transmitting signals restricted to less than 30 MHz?
The Q of a resonant transmission line is
Propagation constant of a transmission line is
Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication ______.
(i) The intensity of a light pulse travelling along a communication channel decreases exponentially with distance x according to the relation I = Ioe–αx, where Io is the intensity at x = 0 and α is the attenuation constant. Show that the intensity reduces by 75 per cent after a distance of `((In 4)/α)`
(ii) Attenuation of a signal can be expressed in decibel (dB) according to the relation dB = `10 log_10 (I/I_0)`. What is the attenuation in dB/km for an optical fibre in which the intensity falls by 50 per cent over a distance of 50 km?
