The Harmfulness of Wireless Signal Blockers: A Misunderstood Topic

In recent times, there has been widespread circulation of an article claiming that wireless signal blockers are harmful to human health. This has sparked a heated debate both online and offline regarding the potential dangers of these devices. In order to shed light on this issue, our reporter conducted an interview to understand what wireless signal blockers are and how they work.

Understanding the Functionality:

To gain insights into the working principle of wireless signal blockers, our reporter interviewed Gu Lianzhong, a physics professor at Hebei Normal University. Gu explained that the functioning of these blockers involves the generation of scanning signals by a sawtooth wave signal generator. These signals are then inverted by an inverter and modulated onto three frequency bands that are the same as the downlink frequencies of CDMA, GMP, and PHS. The modulated scanning signals are amplified by a power amplifier, with the power controlled by a voltage regulator to ensure that the emitted power is less than 1W. The amplified scanning signals are then transmitted into the air in the form of radio waves. The interference caused by these scanning signals disrupts the reception of normal data from base stations, rather than relying on increased power or countering the base station’s signal.

The Safety Aspect:

Gu Lianzhong believes that wireless signal blockers are not harmful to human health due to their low power (less than or equal to 1W) and limited range of influence (around 20-30 meters). The electromagnetic signals emitted by these blockers fall entirely within the frequency range designated for mobile phones by the national regulations. Therefore, they do not interfere with the human brain or affect normal thinking processes.

Experimental Verification:

To further validate these claims, our reporter obtained a signal blocker and placed it on a desk, resulting in a complete loss of mobile phone signals. After 17 minutes, the blocker was turned off. Throughout the entire process, the reporter, who was working near the blocker, did not experience any discomfort. Subsequent communication with colleagues in the office revealed that none of them had noticed any bodily reactions or even realized that the signal blocker had been activated.

Government Regulations and Recommendations:

According to our investigation, the Ministry of Education currently does not impose mandatory requirements on the use of wireless signal blockers in various provinces. However, whether or not students encounter these blockers during exams, there is no need for excessive concern. Gu Lianzhong advises students that as long as the products are produced by reputable manufacturers and have undergone rigorous testing by authoritative institutions such as the “China Center for Disease Control and Prevention’s Environment and Health-Related Product Safety Institute,” their electromagnetic radiation intensity will not pose any harm to the human body. He further assures that the experience is similar to using mobile phones in daily life.


The emergence of wireless signal blockers has played a role in curbing the increasing problem of “mobile phone noise pollution.” However, as a type of mobile communication interference device, it is inevitable that people may perceive the electromagnetic radiation it generates as a potential health hazard. These blockers are low-energy consumption devices primarily used to block signal communication between mobile phones and base stations. This ensures the integrity of exams by preventing the leakage of test questions and guarantees fair competition among students. Due to their minimal energy requirements and the use of fully enclosed protective plastic casings, they possess features such as dust and damage resistance, as well as effective radiation blocking. Therefore, wireless signal blockers of good quality do not pose any safety issues. However, it is important to exercise caution when purchasing these devices, as some smaller manufacturers may use inferior materials to cut costs. We recommend choosing reputable companies that provide good after-sales service to ensure the quality of the purchased products.