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Why do walkie-talkies still need to use antennas compared to mobile phones?

Date:Dec 29, 2020

Although walkie-talkies are nearly half a century earlier than mobile phones, today's mobile phones do not have an external antenna, but walkie-talkies still use a long antenna. Why is this? In fact, this starts with the working frequency of the walkie-talkie.


First, we should clarify a concept: the higher the frequency, the shorter the wavelength, and the longer the antenna. Compared with mobile phones, the frequency of walkie-talkies is generally a low frequency, more concentrated in tens of megabytes to hundreds of megabytes. The mobile phones we usually use generally communicate on the two frequencies of 900MHz and 1800MHz, while our civilian walkie-talkies work The frequency is between 409 and 410MHz. Walkie-talkies are generally point-to-point communication methods, with fewer base stations. The low frequency band can overcome the influence of terrain and buildings on communication quality. In other words, in the point-to-point through mode, the lower the frequency, the farther the propagation. In order to transmit the radio signal as much as possible, a longer antenna is needed.


Because the frequency is lower, the wavelength of the corresponding frequency will be longer, and the wavelength is equal to the speed of light divided by the frequency. If the antenna can transmit an intercom signal with the highest energy possible, it needs to be designed as a "wavelength/2" size. You can find an example to calculate. Compared with mobile communications-mobile phones, if the frequency is 10 times lower, the corresponding wavelength will be 10 times higher, and the size of the antenna will be larger.

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Of course, it is impractical to design an antenna that meets the physical size of the wavelength requirement in many cases, but it is still possible to get a better transmission and reception effect if it is as close as possible to the size of "wavelength/2". And one of the principles to be followed in electrical design.


So in general, the longer the better. On the other hand, although the signal is very important, the design of the mobile phone cannot blindly pursue the signal. As long as it can communicate, battery life, screen, camera, etc. are the most important. Walkie-talkies are different. The communication effect is always The highest priority.


In fact, our earliest mobile phones also had antennas, such as the classic "Big Brother". Although mobile phones do not have the long external antennas of the early days, the antenna is actually transformed from the outside into an internal hidden antenna through industrial design. However, with the advancement of technology, mobile phones have gradually become our necessities and consumer goods. In addition to antenna size, aesthetics and portability need to be considered. This has caused fundamental design differences between mobile phones and walkie-talkies.



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Although today's mobile phones do not have the raised external antennas of the early days, many articles have been made internally to maintain the effective size of the antenna as much as possible. In contrast, the primary principles of the design of walkie-talkies are good signal transmission and reception capabilities, and reliability. The requirements for portability and aesthetics are relatively low. Under such conditions, large-size raised antennas are acceptable.

Mobile phones basically rely on base stations for communication, and long-distance communication without base stations is not required and impossible. This is why when we go to a place where there are few mobile phone base stations and poor signal coverage, our mobile phones basically cannot make calls or receive signals, but walkie-talkies do not have this problem. He relies on Radio waves realize point-to-point communication, which can be transferred without the aid of base stations.


In the communication process of the walkie-talkie, it does not rely on the network signal of the operator, and the use scene does not have particularly high requirements on the appearance. The significance of the communication effect is absolutely higher than the appearance design. Moreover, the operating frequency of the walkie-talkie is much lower than that of the mobile phone, and a larger and longer antenna is required to send the signal better.


In addition, the mobile phone itself uses a high operating frequency. 4G mobile phones are now common, and 5G is slowly beginning to use. According to the most basic law, the higher the frequency, the shorter the wavelength, so the antenna required when receiving signals is short. In the early days, it was made on the outside, and in the later period, it was processed on the inside for aesthetics.


In short, although both walkie-talkies and mobile phones use radio waves, their antennas are different. In addition to their own frequencies, they also have a lot to do with the purpose of use.