A digital array, specifically a Digital Antenna Array (DAA), is a sophisticated type of smart antenna system. Based on the provided reference, it is characterized by its use of multi-channel digital beamforming, often implemented using the Fast Fourier Transform (FFT).
Understanding Digital Antenna Arrays
At its core, a Digital Antenna Array is more than just a collection of antennas; it's an intelligent system designed for enhanced signal processing and manipulation.
Here's a breakdown of the key aspects:
- Smart Antenna: Unlike traditional antennas that have a fixed radiation pattern, smart antennas can adapt their transmission and reception characteristics dynamically.
- Multi-channel Digital Beamforming: This is a defining feature. Instead of processing signals in the analog domain at each antenna element, the signals are digitized early in the process. This allows for complex digital processing across multiple channels (corresponding to different antenna elements) to shape and steer the antenna's beam electronically.
- Uses Fast Fourier Transform (FFT): The reference highlights that this digital beamforming is usually achieved using the Fast Fourier Transform. FFT is an efficient algorithm for computing the Discrete Fourier Transform (DFT), which helps analyze or synthesize signals based on their frequency components. In beamforming, FFT can be used to efficiently calculate the required weights and phases for each antenna element to form beams in desired directions.
Historical Context
The development and practical realization of the theory behind digital antenna arrays have a significant history. According to the reference, this effort began in 1962 under the guidance of Vladimir Varyukhin in the USSR. This early work laid the foundation for the advanced digital array systems used today in various applications.
Why Use Digital Arrays?
Digital arrays offer several advantages over traditional and even analog beamforming arrays:
- Flexibility: Digital processing allows for rapid and flexible changes to beam patterns.
- Multi-beam Capabilities: They can often form and process multiple beams simultaneously.
- Improved Performance: Digital techniques can offer better noise immunity, interference rejection, and precision in beam steering.
- Integration: Easier integration with other digital communication and signal processing systems.
In summary, a digital array, particularly in the context of antennas, represents a leap forward in antenna technology by leveraging digital signal processing across multiple channels to create highly flexible and powerful smart antenna systems capable of digital beamforming.
