How Do Passive Cell Phone Antennas Work?

Cell phone antennas are placed on or within a cell phone to increase its ability to connect to tower signals. The cell tower holds the transmitter that cell phones operate from. There are objects and situations that will block cell phone signals, and there are also areas called dead zones that signals cannot reach.

Cell phone towers can only reach a limited area of two to five miles in diameter to the tower. Most cell phone companies build a landscape of towers that overlap so there are no lapsed signals. But there are limits to what the towers offer, and there are places where some cell phone companies do not have signals. If you are on the fringe of these areas, your cell phone may not work. You may need a passive cell phone antenna.

The term "passive" simply indicates that the antenna is not directly attached to the signal transmitter. Cell phone signals are often difficult to reach inside buildings or cars, and passive antennas are meant to strengthen the signals. Many building owners use a passive cell phone antenna, also called a passive repeater, to solve this problem.

Through the application of an outdoor panel antenna, usually mounted at the top of the building and pointed toward the appropriate cellular tower, the signal is received. This antenna communicates the signal to a high-beam bi-directional signal amplifier located inside the building. It amplifies the signal, which in turn expands the area, and cell phones, that can receive it. The magnified signal is then transmitted through a series of interior amplifiers located on each floor. This gives cell phone users a stronger but not guaranteed signal inside the building.

Antennas are transducers. Transducers convert an electromagnetic wave into an electrical current. For cell phones, the electrical current is a radio frequency. A passive antenna attached to a car, a home or even directly to a cell phone does not add power. Instead, it gathers and redirects the signals, improving the possibility of reception inside or outside of the car. The closer the phone is to the passive antenna, the better. Alternatives are available for cell phones with antenna ports.