Understanding the Directional Antenna of Cell Phone Signal Blockers


Cell phone signal blockers are commonly equipped with two types of antennas: omnidirectional antennas and directional antennas. While customers easily understand the coverage range and signal transmission direction of omnidirectional antennas, they often have limited knowledge about the signal transmission direction and coverage range of directional antennas. This article aims to clarify the misconceptions and provide a better understanding of the directional antennas used in cell phone signal blockers.

Understanding Directional Antennas:

As the name suggests, directional antennas have a specific directionality. To explain this concept to customers who are unfamiliar with wireless communication, an analogy is often used. It is said that the wireless signal emitted from a directional antenna is similar to the light emitted from a flashlight, as it is directed towards a specific direction. However, this analogy can lead to misunderstandings.


Customers often ask whether using a directional antenna in a cell phone signal blocker will eliminate interference on the sides and rear. This question arises from the misconception that the light emitted from a flashlight only illuminates the front, while the sides and rear remain in darkness due to the flashlight’s reflector. However, when a cell phone signal blocker is equipped with a directional antenna, the transmission path and coverage range of the interference signal are not the same as the transmission of light from a flashlight.

Understanding the Coverage Range:

Through testing and 3D modeling of the signal transmission of directional antennas in a microwave darkroom, it becomes evident that interference signals continue to be emitted on the sides and rear. However, the signal strength and transmission distance in these areas are significantly lower than in the front. The wireless signal emitted in the front direction of a directional antenna is referred to as the main lobe, which has a specific lobe angle. The flashlight analogy primarily focuses on this main lobe’s coverage area, disregarding several secondary lobes.

Different Types of Directional Antennas:

It is important to note that there are various classifications of directional antennas, each with different working principles, antenna materials, and manufacturing methods. Consequently, the main lobe, secondary lobes, lobe angles, and transmission distances of directional antennas can vary significantly. When selecting a directional antenna for a cell phone signal blocker, customers must carefully evaluate and choose the most suitable option based on their specific requirements.


In conclusion, directional antennas used in cell phone signal blockers have a specific directionality, but they do not completely eliminate interference on the sides and rear. The analogy of a flashlight’s light transmission does not accurately represent the transmission path and coverage range of interference signals from directional antennas. Customers should consider the characteristics and specifications of different directional antennas to make an informed decision when configuring a cell phone signal blocker.