Mobile phone signal enhancement stickers are hot-selling, experts: The principle is not valid, and there is no obvious enhancement in actual measurement

Just stick a metal sticker on the "effective position" on the back of the phone, and the signal can be increased from 1 bar to 3 bars. Recently, "mobile phone signal enhancement stickers" have been hot selling online, so is this small sticker a black technology or a "IQ tax"?

Relevant merchants claim that such enhancement stickers can intelligently amplify signals and are fully applicable in basements, villas, mountainous areas, rural areas and other places, and that the signals of various operators can be greatly improved. Some merchants also stated that several mobile phone signal enhancement stickers have the functions of improving mobile phone performance, reducing radiation levels, and extending battery life, and provided relevant product manuals as "proof".

Xinhua News Agency conducted an investigation into this. Li Jinxin, a professor at the School of Electronic Information at Hangzhou Dianzi University, tested mobile phone signal enhancement stickers in the Zhejiang Willic Communication Laboratory. Regarding the statement that "the principle of the enhancement sticker is to enhance the signal reception range by lengthening the wavelength of the signal received by the mobile phone's built-in antenna", Li Jinxin said: "This does not make sense in principle." He said that first of all, the wavelength cannot be "lengthened" in real life; secondly, amplifying anything requires energy, and the sticker is a "passive antenna" that cannot provide energy to effectively amplify the signal.

So is it true that stickers can "amplify signals through resonance"? According to experts, the unit representing the signal strength of mobile phones is dBm. Since the signal strength of mobile phones is generally small, dBm is generally a negative number. The reporter saw in the laboratory scene that the mobile phone was fixed in one position. When the mobile phone had no stickers, its signal strength value fluctuated between -81dBm and -79dBm. "The larger the value of signal strength dBm, the better the signal. In the experimental scene, the fluctuation range of the test change was within the range of plus or minus 3dB. In the laboratory scene test, the sticker had almost no ability to enhance the signal." said Lv Xiaoliang, senior engineer of Zhejiang Welike Communication Co., Ltd.

Experts also conducted tests in fast-moving subways, open spaces, elevators, etc. The result was that after applying the enhancement sticker, the mobile phone signal did not increase but decreased.

It seems that mobile phone signal enhancement stickers are useless and are completely a waste of money, so consumers should keep their eyes open and conduct some research before purchasing.