The antenna is a device with a simple appearance,a good antenna is conducive to improving the quality of the radio wave signal and enhancing the effect of wireless communication. For amateur radio enthusiasts, the choice of antenna needs to consider the use of radio wave band, communication distance, communication direction, use occasion, erection method, cost and other use factors, as well as input impedance, frequency band broadband, center frequency, input power, gain , Standing wave, directivity pattern and front-to-back ratio and other antenna characteristics.
- The radio wave band refers to which band the radio wave signal radiated by the antenna is in. Each type of antenna corresponds to a certain application frequency band and band, and single-band antennas cannot be used across bands. In terms of performance, the performance of single-band antennas is generally better than that of multi-band antennas.
- The distance of the communication is based on the signal coverage of the communication to consider which antenna type to choose. The radiation efficiency of different types of antennas is different. Under the same conditions, the radiation efficiency of directional antennas (such as Yagi antennas) is higher than that of omnidirectional antennas.
- The direction of communication refers to the transmitting/receiving direction of the radio wave signal when the antenna needs to be considered when selecting the antenna. When using a single-directional communication, you can choose a directional antenna to improve the communication effect; when using an indefinite communication, you must reduce the communication effect and use an omnidirectional antenna.
- The occasion of use mainly refers to the use of antennas such as handheld, vehicle-mounted, and base. Antennas used in different occasions have certain site application characteristics. For example, handhelds should choose small and flexible antennas, vehicles should choose antennas with low wind resistance, and base stations should choose high-efficiency antennas.
- Costs reflect the “moderate” spirit of amateur radio. Brand antennas with superior performance generally have higher prices. Although self-made antennas are lacking in performance, they are low in cost. Therefore, when setting up a radio station, it is best to investigate various antenna information and make a budget.
- The input impedance mainly considers the matching problem of the antenna feeder system when the system is connected, which involves the radio transmitter module, feeder, antenna and other equipment. The antenna feeder system with excellent impedance matching can reduce the standing wave value, reduce the loss of the electric signal transmission process, and improve the communication effect.
- The frequency bandwidth refers to the working frequency range of the antenna, which generally corresponds to the upper and lower frequency range of the center frequency point. In the frequency range of the center frequency point, the antenna efficiency is higher and the gain is larger. In short-wave communication, antenna tuning is often used to expand the frequency band and wideband, and to make the antenna work best.
- The center frequency is the operating frequency with the best antenna performance. At this time, the antenna has the highest efficiency, the largest gain, and the smallest standing wave. For amateur radio applications, the middle value of the commonly used frequency range should be set as the center frequency of the antenna.