An advantage of modulation is the use of ______.

The correct option is 1

Concept:

Modulation is the process of varying some characteristics (such as amplitude, frequency, or phase) of a carrier signal (usually a high-frequency signal) with the information signal. This process allows the signal to be transmitted over long distances.

The size of an antenna is usually approximately proportional to the wavelength of the signal it is designed to transmit or receive. The wavelength (λ) is inversely proportional to the frequency (f) of the wave, according to the relationship λ = c / f, where c is the speed of light.

Lower-frequency (longer-wavelength) signals would require larger antennas for efficient transmission and reception. By modulating a low-frequency information signal onto a high-frequency carrier, we can practically transmit the information with a much smaller antenna, because the effective wavelength is now much smaller.

Hence, modulation can enable the use of smaller, more practical antennas, which is especially important for mobile and handheld devices, and for  practical installation and maintenance of antennas in general.

Here's why the other options are not correct:

2) Smaller circuit - Modulation often requires additional circuit complexity (modulators, demodulators) compared to simply transmitting baseband signals.

3) Lower bandwidth - Modulating a signal usually increases its bandwidth because the frequency content of the original signal is spread out over a range around the carrier frequency.

4) Lesser power - Modulation techniques in themselves don't reduce the power needed for transmission, but they do help in efficient utilization of the available power. More advanced digital modulation techniques can provide more bits per second per watt, but they don't reduce the transmitter's power requirement.