Rf microwave usually refers to radio waves with a wavelength (λ) between 25px and 250px, corresponding to a frequency (f) of 30GHz to 3GHz, and millimeter-wave usually refers to radio waves with a wavelength (λ) between 1mm and 10mm, corresponding to a frequency (f) of 300GHz to 30GHz. The relationship between wavelength (λ) and frequency (f) is expressed as λ =c/f, where λ is measured in meters, c is the speed of light (3*10⁸m/s), and f is measured in Hz.

       Radio Frequency (RF) refers to the radio frequency current, representing the oscillation frequency of high-frequency alternating current changes electromagnetic waves. The frequency is measured in Hertz (Hz) and is equal to the number of oscillation cycles per second (1/S). RF can refer to frequencies as high as 300 GHZ or as low as 30KHz.

       Radio frequency applications are widely used in daily applications, such as: radio broadcasting (AM/FM radio, etc.); Wireless communication (5G, mobile phone, WiFi, Bluetooth, etc.); Radio frequency remote control (car door remote control, drone, etc.); Remote sensing (weather or surveillance radar, etc.); Satellite navigation (GPS, Beidou, Galieo, Glonass); Imaging (X-ray scanner, etc.).

  The design of RF circuits needs to take into account the transmission and processing of signals, so some special components and technologies need to be used, such as: The components commonly used in RF circuits include filters, multiplexers, resonators, amplifiers, mixers, antennas, etc. These components need to have a high quality factor and a low noise factor to transfer the signal quality, in addition to the RF circuit equipment also needs to take into account the signal matching and impedance matching to ensure the transmission efficiency and stability of the signal.