Which component is responsible for improving signal strength in a transmitter?

The component responsible for improving signal strength in a transmitter is the power amplifier. In a transmitter system, the signal generated by the modulator is often relatively weak, and to ensure it can be effectively transmitted over long distances, it must be significantly amplified.

The power amplifier takes the low-power signal from the modulator and boosts its amplitude, allowing it to overcome losses in the transmission medium and enabling it to reach farther distances with adequate strength. This amplified signal is then sent to the antenna for broadcasting. Power amplifiers are essential for ensuring that the transmitted signal remains clear and maintains its integrity across various conditions, which is crucial for effective communication.

In contrast, while the oscillator generates the initial signal frequency and frequency stability, and the modulator modifies the signal to encode information onto that frequency, neither directly increases the power of the signal for transmission. The demodulator is involved at the receiving end, extracting information from the modulated signal but does not play a role in enhancing signal strength in the transmitter.