An active antenna operates by incorporating active electronic components, typically an amplifier, into its design to enhance the reception and transmission of radiofrequency signals. Here’s a detailed explanation of how an active antenna works:
Components of an Active Antenna:
1. Antenna Element:
Similar to passive antennas, active antennas have a physical element designed to capture and transmit radiofrequency signals. This element is typically a dipole, monopole, loop, or another antenna design depending on the application.
2. Amplifier:
The key distinguishing feature of an active antenna is the inclusion of an amplifier. This electronic component is crucial for boosting the strength of the received signals. The amplifier can be integrated into the antenna structure or placed in a separate housing, connected to the antenna through a coaxial cable.
Working Mechanism:
1. Signal Reception:
When radiofrequency signals from the surrounding environment interact with the antenna element, they induce an electrical current in the antenna. In passive antennas, this induced current is directly fed to the receiver. However, in active antennas, the signal is first passed through the built-in amplifier.
2. Amplification:
The amplifier in the active antenna plays a pivotal role. It takes the weak signals received by the antenna and amplifies them. The amplification process increases the strength of the signals, making them more robust and improving the antenna’s ability to capture weaker signals.
3. Filtering and Processing:
Some active antennas may include additional features such as filters or processing circuits. These components help in refining the received signals by removing unwanted noise or interference. Filtering is particularly important in environments where various signals or sources of interference are present.
4. Signal Transmission (if applicable):
In cases where the active antenna is used for two-way communication, the amplified signals are fed back into the transmitter circuit for transmission. The amplifier’s role is not limited to reception; it can also enhance the strength of signals being transmitted.
Advantages of Active Antennas:
1. Increased Signal Strength:
The primary advantage of active antennas is their ability to boost the signal strength. This is especially beneficial in situations where the received signals are weak or attenuated.
2. Improved Signal-to-Noise Ratio:
By amplifying the signals and potentially incorporating filtering mechanisms, active antennas can enhance the signal-to-noise ratio. This results in clearer reception, particularly in environments with high levels of interference.
3. Flexibility:
Active antennas are often more versatile as the amplifier allows for adjustments to the antenna’s performance characteristics. This flexibility is valuable in adapting to different reception conditions.
In summary, the active antenna’s operational principle revolves around amplifying received signals to improve reception and, in some cases, transmission. The inclusion of an amplifier distinguishes active antennas from their passive counterparts, providing advantages in terms of signal strength and overall performance.