Microwaved RF frequency multipliers are electronic devices that generate signals having frequencies that are integral multipliers of their input signal frequencies. These devices have applications in electronic instruments, radar, electronic warfare, and communication systems. This article covers theory and design of these devices that operate from the megahertz to millimeter‐wave regions. Detailed discussions of both passive and active realizations are included along with state‐of‐the‐art practical design examples. Over 170 references covering the current multiplier technology in RF and microwave bands are included.