In order to improve the antenna performance of FM radio, we can start from three aspects: ① adjust the physical form of antenna-erect the Car Antenna vertically, stretch the home antenna to the maximum length, and aim at the direction of signal Transmission tower by using the linear propagation characteristics of FM; (2) Add gain antenna module, choose high-sensitivity rubber sleeve or shark fin antenna, and its anti-interference design can filter electromagnetic interference sources such as engines and household appliances; ③ Keep away from metal obstacles and electronic equipment to avoid signal shielding or attenuation. For example, the car antenna should avoid the wiper motor, and the home antenna should keep a distance of more than 1m from the router. The coverage difference of different broadcasting frequency bands stems from the propagation principle: FM signals spread in a straight line, and the coverage area is usually limited to the city (with a radius of about 50-100 kilometers) due to the curvature of the earth, which is also the reason why signal interruption is easy to occur in mountainous areas or high-rise areas; AM medium waves are propagated by ground waves, covering the provincial level (hundreds of kilometers), but the sound quality is easily affected by ionospheric changes. Short wave achieves global coverage through ionospheric reflection, which is suitable for international broadcast reception. However, due to the fluctuation of atmospheric conditions, the signal is sometimes strong and sometimes weak. Choosing an adaptive FM AM Antenna is the core of signal stability: the vehicle-mounted scene priority rubber sleeve Car Antenna, whose flexible material can be hidden behind the windshield, has both anti-vibration and waterproof properties; For home stereo, it is suggested to choose telescopic rod Car Radio Antenna or adsorption magnetic base antenna, which can expand the receiving range with signal amplifier; For marine or outdoor equipment, a special antenna resistant to salt fog is needed to ensure continuous work in a humid and highly corrosive environment. High-quality walkie talkie antenna can not only reduce noise, but also restore the delicate layering of broadcast audio, so that news broadcasts and music programs can present a CD-level listening experience. Q: Is it really useful to install a signal amplifier? How to choose? A: The effect of weak signal area is remarkable! It is suggested to choose a low noise amplifier (LNA) suitable for FM frequency band (87.5-108MHz), and the gain should be controlled at 10-20dB, which will easily introduce distortion if it is too high. Give priority to the model with shielding layer to reduce external interference. Q: Is it better to install the car antenna on the roof or the rear window? A: The center of the roof is the best! The FM signal propagates in a straight line, and the height of the roof can reduce the body occlusion; If the pursuit of concealment, the rear window glass needs to choose non-metallic film pasting area to avoid metal heat insulation layer shielding signals.
