1. The operating frequency range of a walkie-talkie is usually very low, ranging from several tens of megahertz to several hundred megahertz. This is because most intercom systems do not have repeater stations (or base stations) for low-cost and convenient deployment. Basically, they are point-to-point. The walkie-talkie has a walkie-talkie mode, so the low working frequency band can overcome the influence of the landform and the building on the communication quality, that is, the lower the frequency, the farther it spreads;

2. It is precisely because of the low frequency that the frequency corresponding to the interphone's frequency will be longer, and the wavelength is equal to the speed of light divided by the frequency. If the antenna can transmit the intercom signal as high energy as possible, it needs to be designed as a "wavelength / 2" size, you can find an example calculation. Compared with mobile communication mobile phones, if the frequency is ten times lower, the corresponding wavelength will be ten times higher and the antenna size will be larger;

3, Of course, it is impractical to perfectly design an antenna that meets the physical size of the wavelength requirements. However, as far as possible, the size of the "wavelength/2" will be closer, and the better transmission and reception results will be obtained. One of the principles to be followed in engineering and electrical design;

4, In addition, the mobile phone is a consumer product after all, in addition to the size of the antenna also need to consider the beauty and portability, which is inconsistent with the design goals of the walkie-talkie, although the current mobile phone does not have the kind of protruding external antenna, but the internal still A number of articles have been made to keep the effective size of the antenna as low as possible, such as microstrip antennas, inverted F-shaped patch antenna, and apple border antennas, for example. In contrast, the primary principles for the design of walkie-talkies are good signal transmission and reception capabilities, and reliability, relatively low requirements for portability and aesthetics, and large-sized raised antennas under such conditions are acceptable.