Technical Introduction Radio refers to electromagnetic waves that propagate in all free spaces (including air and vacuum), which is a limited frequency band with an upper limit frequency of 300GHz (gigahertz) and a lower limit frequency that is relatively inconsistent. In various radio frequency specifications, common ones include 3KHz-300GHz (ITU International Telecommunication Union regulations), 9KHz-300GHz, and 10KHz-300GHz. Principle Radio technology is the technology of transmitting signals through radio waves. The principle of radio technology is that changes in the strength of the current in a conductor generate radio waves. By utilizing this phenomenon, information can be loaded onto radio waves through modulation. When radio waves propagate through space and reach the receiving end, the electromagnetic field changes caused by the radio waves will generate current in the conductor. By demodulating and extracting information from changes in current, the purpose of information transmission is achieved. The earliest application of purpose radio was in navigation, using the Morse telegraph to transmit information between ships and land. Radio has various application forms, including wireless data networks, various mobile communications, and radio broadcasting. The following are some of the main applications of wireless technology: [2] Communication wireless communication occupies an extremely important position in modern communication, and wireless communication is used in almost any field, including commerce, meteorology, finance, military, industrial, civilian, and so on. We can see a wide variety of wireless communication systems from various aspects such as communication systems, modulation methods, and multiple access methods. Category: Communication systems, satellite communication systems, cellular mobile communication systems, wireless paging systems, shortwave communication systems, microwave communication systems, etc. Modulation methods include AM, FM, LSB, USB, ISB, FSK, PSK, MSK, GMSK, QAM, etc. Multiple access methods include Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Code Division Multiple Access (CDMA). The earliest form of sound broadcasting was maritime radiotelegraphy. It uses a switch to control the emission of continuous waves, thereby generating intermittent sound signals, known as Morse codes, in the receiver. AM broadcasting can spread music and sound. Amplitude modulation broadcasting uses amplitude modulation technology, which means that the higher the volume received at the microphone, the greater the energy emitted by the radio station. Such signals are susceptible to interference from sources such as lightning or other disturbances. FM broadcasting can transmit music and sound with higher fidelity than AM broadcasting. For frequency modulation, the higher the volume received at the microphone, the higher the frequency of the transmitted signal. FM broadcasting operates in the Very High Frequency (VHF) range. The higher the frequency band, the larger the frequency bandwidth it possesses, which can accommodate more radio stations. At the same time, the propagation of radio waves with shorter wavelengths is also closer to the characteristics of straight propagation of light waves. The sideband of FM broadcasting can be used to transmit digital signals such as radio station identification, program name introduction, website address, stock market information, etc. In some countries, when being moved to a new area, FM radio can automatically find the original channel according to the sideband information. Voice radio stations used in navigation and aviation use VHF amplitude modulation technology. This enables the use of lightweight antennas on aircraft and ships. Government, fire, police, and commercial radio stations typically use narrowband frequency modulation technology on dedicated frequency bands. These applications typically use a bandwidth of 5KHz. Compared to the 16KHz bandwidth of FM radio or TV audio, fidelity has to be sacrificed. Civil or military high-frequency voice services use shortwave for communication between ships, aircraft, or isolated locations. In most cases, single sideband technology is used, which can save half of the frequency band compared to amplitude modulation technology and more effectively utilize transmission power. Terrestrial Trunked Radio (TETRA) is a digital trunked telephone system designed for special departments such as the military, police, and emergency services. 2. Cellular or mobile phones are currently the most commonly used wireless communication methods. The cellular telephone coverage area is usually divided into multiple cells. Each cell is covered by a base station transmitter. In theory, the shape of the community is a honeycomb shaped hexagonal shape, which is also the source of the name for cellular phones. The widely used mobile phone system standards currently include GSM, CDMA, TDMA, and LTE. The dominant standards for 3G mobile communication services provided by operators are UMTS and CDMA2000, while the 4G mobile communication services provided by operators are TD-LTE and FDD-LTE. There are two forms of satellite telephone: INMARSAT and Iridium system. Both systems provide global coverage services. INMARSAT uses geostationary satellites and requires directional high gain antennas. Iridium is a low orbit satellite system that directly uses a mobile phone antenna. 3. The typical analog television signal for television is to modulate the image amplitude, frequency adjust the accompanying sound, and synthesize them to propagate in the same signal. Digital TV uses MPEG-2 image compression technology, which only requires approximately half of the bandwidth of analog TV signals. 4. Emergency position indicating radio beacons (EPIRBs), emergency positioning transmitters or personal positioning beacons are small radio transmitters used to locate personnel or measurements through satellites in emergency situations. Its function is to provide precise locations for rescue personnel to target, in order to provide timely rescue. 5. Data transmission digital microwave transmission equipment, satellites, etc. usually use Quadrature Amplitude Modulation (QAM). The QAM modulation method utilizes both the amplitude and phase loading information of the signal. In this way, a larger amount of data can be transmitted on the same bandwidth. IEEE802.11 is the current standard for Wireless Local Area Network (WLAN). It adopts the 2GHz or 5GHz frequency band and has a data transmission rate of 11 Mbps or 54 Mbps. Bluetooth is a technology for short range wireless communication. 6. Identification utilizes active and passive radio devices to identify and indicate the identity of objects. (Refer to Radio Frequency Identification) 7. Other amateur radios are radio station communication in which radio enthusiasts participate. Amateur radio stations can