This APP is designed for teachers, students and practitioners of electromagnetics. We hope this APP can help you calculate more easily, and you can also use it to check the results.

Electromagnetic wave is long wavelength, low frequency electromagnetic wave. A wave is a form of energy. There are many kinds of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, X-rays, gamma rays and so on. Wave describes the change of physical quantity in space and time. For electromagnetic waves, this quantity is the magnitude of the electric and magnetic fields. When electromagnetic waves are generated, the size of the electric and magnetic fields at a point in space changes. It is measured in Hertz (Hz) or cycles per second (C/s). Most radars operate in ultra-short wave and microwave bands, with frequencies ranging from 30 to 300,000 MHZ and corresponding wavelengths ranging from 1mm to 10m, including very high frequency (VHF), ultra-high frequency (UHF), ultra-high frequency (SHF) and extremely high frequency (EHF). Below the frequency of 1ghz, due to communication, television and other channels are occupied resulting in spectrum congestion, general radar is less used. Only a few long-range and beyond-line-of-sight radars use this band. At frequencies higher than 15ghz, absorption of air and water molecules is severe. When it is higher than 30ghz, atmospheric absorption increases sharply, making it difficult for radar equipment to deal with and increasing the noise inside the receiver. Only a few millimeter-wave radars operate in this band.