Antennas are same as radios, and divided into single-band, dual-band, and multi-band antennas according to the number of receiving frequency bands. For dual-band and multi-band radios, please use dual-band and multi-band antennas. If you always use the single-band antenna, high standing wave ratios will be generated in another frequency bands, and the reflected power is very large. then long-term use will damage the radios.
The length of the antenna is determined by the wavelength of the center frequency. However, the length of the antenna is not equal to the wavelength. It is usually 1/4 or 5/8 wavelength. Generally, it will be indicated when purchasing the antenna, because it will directly affect the efficiency and gain of the antenna.
According to the antenna length, it can be divided into long antenna and short antenna. In order to meet the wavelength requirements, long antennas generally use straight transducers, and short antennas use induction coils. In comparison, long antennas are better than short antennas. Therefore, if conditions permit, try not to choose ultra-short antennas such as thumb antennas, as the saying goes, "one inch long and one inch strong".
In order to carry it conveniently, we can also choose a highly flexible antenna, such as a whip antenna, a folding antenna, and so on.
One thing that must be said about the whip antenna is that the whip antenna must be pulled out completely to use. Especially for dual-band or multi-band whip antennas, even if only one frequency band is used, all other frequency bands must be pulled out.