Question

We do not transmit low frequency signal to long distance because-
(a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength
(b) Effective power radiated by a long wavelength baseband signal would be high
(c) We want to avoid mixing up signals transmitted by different transmitter simultaneously
(d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well
Therefore, the most suitable option will be

• A. All statements are true
• B. (a), (b) and (c) are true only
• C. (a), (c) and (d) are true only
• D. (b), (c) and (d) are true only

Answer 1

The Correct Option is C

 The question asks why low-frequency signals are not transmitted over long distances and evaluates different statements related to this topic. Let's analyze each option to determine the most suitable choice.

1. Option (a): The size of the antenna should be comparable to the signal wavelength, which is unreal solution for a signal of longer wavelength.
   • For effective transmission, the antenna size should be approximately equal to the wavelength of the signal. Low-frequency signals have longer wavelengths, which would require impractically large antennas for efficient transmission.
2. Option (b): Effective power radiated by a long-wavelength baseband signal would be high.
   • This is incorrect. Long-wavelength (low-frequency) signals generally radiate less power efficiently unless amplified or carried by a higher frequency wave.
3. Option (c): We want to avoid mixing up signals transmitted by different transmitters simultaneously.
   • Low-frequency signals are more susceptible to interference, particularly when multiple signals are present, leading to mixing and distortion.
4. Option (d): Low-frequency signal can be sent to long distances by superimposing with a high-frequency wave as well.
   • This reflects the process of modulation, where low-frequency signals are transmitted effectively over long distances by being superposed with high-frequency carrier waves, allowing for smaller antennas and more efficient power use.

Based on the analysis, statements (a), (c), and (d) are true, making the correct answer: (a), (c), and (d) are true only.