The optimal FM AM Antenna length of FM radio is not a fixed value, which is closely related to the wavelength of FM band (87.5-108MHz). Theoretically, when the Walkie Talkie Antenna length is 1/4 of the signal wavelength, the receiving efficiency is the highest. According to the formula "wavelength = light speed ÷ frequency", the wavelength corresponding to the central frequency of 100MHz in FM band is about 3 meters, so the ideal antenna length of 1/4 wavelength is about 75 cm. However, in practical application, due to environmental interference, radio internal circuit matching and other factors, the Omni Directional Antenna with a length of 60-90 cm can usually achieve good reception effect. Car Antenna can be called the "signal bridge" of radio equipment. As a converter between electromagnetic waves and electrical signals, it captures and converts electromagnetic waves in space into processable electrical signals, and vice versa. Taking FM/AM antenna as an example, its working principle is based on electromagnetic induction. When the changing electromagnetic field passes through the Car Radio Antenna conductor, it will generate induced current, which will be interpreted by the radio as a sound signal. In different scenes, the choice of antenna material is very particular. Automotive FM/AM antennas often use weather-resistant plastics such as nylon and AES. Among them, AES resin (acrylonitrile-EPDM-styrene copolymer) stands out with its excellent weather resistance. Even if it is exposed to ultraviolet radiation, rain erosion and ozone for a long time, it does not need additional coating protection and can work continuously and stably. It is like a signal rock embedded in life, with the precise "nerve" of silver-plated copper core, the tough "bones and muscles" of anti-building skeleton and the invisible "armor" of anti-static shield, which always locks the clear original sound of the radio station for you in daily life. How does the antenna convert electromagnetic waves into sound signals? When the electromagnetic wave passes through the antenna conductor, the induced electromotive force is generated → the target frequency is screened by the LC resonant circuit → the FM signal is restored to audio by the radio demodulation chip → and finally the sound is produced by the speaker. Analogical understanding: the antenna is like a "signal fishing net", and its length determines the size (frequency) of the "electromagnetic wave fish" that can be captured. Why do car antennas use AES plastic instead of nonmetal? Weathering advantage: AES resin (acrylonitrile-EPDM-styrene) has an ultraviolet resistance level of 8 in the temperature cycle of-40℃~80℃, which is better than ordinary ABS plastic. Safety considerations: the metal antenna is easy to lead to lightning, and the plastic material is matched with the built-in copper foil conductor, which not only ensures the signal but also improves the safety. Case data: A brand car antenna is made of AES, and the signal attenuation is less than 3% after 1000 hours of salt spray test.
