The electromagnetic spectrum is a range of all possible frequencies of electromagnetic radiation. It includes all the waves that can travel through space, including radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

The frequency of an electromagnetic wave is the number of waves that pass a fixed point in one second. The higher the frequency, the shorter the wavelength.

Radar waves are electromagnetic waves with frequencies that range from 300 megahertz (MHz) to 300 gigahertz (GHz). Visible waves are electromagnetic waves with frequencies that range from 400 terahertz (THz) to 790 THz.

Therefore, radar waves have lower frequencies than visible waves.