Given below are two statements:
Statement I: There is a need to translate the original low frequency base band signal into high radio frequency before transmission
Statement II: To transmit a signal an antenna is required. As frequency increases size of antenna decreases.
In the light of the above statements, choose the most appropriate answer from the options given below.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both Statement I and Statement II are correct
Statement I — Correct. A low frequency baseband signal has a very long wavelength, which would need an impractically long antenna and would radiate very little power, so it is translated to a high (radio) frequency before transmission.
Statement II — Correct. An antenna must have a size comparable to the wavelength of the signal (at least \( \lambda/4 \)). Since \( \lambda = c/\nu \), a higher frequency means a shorter wavelength and hence a smaller antenna.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Size of the Antenna or Aerial – “For transmitting a signal, we need an antenna or an aerial. This antenna should have a size comparable to the wavelength of the signal (at least λ/4 in dimension) so that the antenna properly senses the time variation of the signal. … We can obtain transmission with reasonable antenna lengths if transmission frequency is high (for example, if ν is 1 MHz, then λ is 300 m). Therefore, there is a need of translating the information contained in our original low frequency baseband signal into high or radio frequencies before transmission.”