Modulating signals at high frequencies is preferred because it allows the wavelength to be smaller than the antenna length, facilitating efficient radiation. Efficient antennas typically include half-wave dipoles or quarter-wave monopoles, which are designed to match the wavelength of the signal. While modulation itself is not directly related to antenna design, the choice of carrier frequency impacts antenna size and signal propagation. The primary considerations for frequency selection include wave propagation characteristics, such as the ability to travel over the horizon or reflect off the ionosphere. Ultimately, while antenna size can influence frequency choice, it is not the main factor driving modulation decisions.
