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Digital Beamforming
Figure 1: analog beamforming of the antenna pattern
Figure 2: digital beamforming of the antenna pattern (Courtesy of EADS Defence & Security Ulm)
Bild 3: Standardised Modular Transmit-/Receive-Module (SMTRM)
Figure 1: analog beamforming of the antenna pattern
Figure 2: digital beamforming of the antenna pattern
Bild 3: Standardised Modular Transmit-/Receive-Module (SMTRM) (Courtesy of EADS Defence & Security Ulm)
Analog Beamforming
Analog beamforming (ABF) means, that the received echo signals from each element of the phased array antenna, are combined at the carrier frequency level. This analog beamformer feeds up to four centralized receivers, down-converting the signal to the basic band (or to an intermediate frequency, IF). The following Analog-to-Digital Converter (ADC) digitizes the IF or video signals.
Digital Beamforming
Digital beamforming (DBF) can be realized at element level or at subarray level. In DBF-architecture there are many digital receivers, one at each of the radiating elements of the antenna. The down-converting to IF-frequency and digitizing the signals is realized at each individual antenna element (or small groups of them). Noise and signal distortion in each receiver are decorrelated among all receivers.
Multiple independent beams steered in all directions can be formed in the digital beamforming processor. The benefits of digital Beamforming include:
- improved dynamic range;
- controlling of multiple beams;
- better and faster control of amplitude and phase.
Standardised Modular Transmit-/Receive-Module (SMTR®)
The Transmit-/Receive-Modules are the key components of based on AESA technology digital beamforming. The modules contain a part of transmitters power amplifier and parts of the receiver, and can be mass-produced to achieve a better cost/performance ratio. These modules may be used in various programmes with only slight individual adaptations being required. By the compact design the line losses are low during the signal processing. For example, the standardised modular transmit-/receive-modules are used in the X-band multi-function fire control radar of the Medium Extended Air Defence System ( MEADS), in the German Armed Forces’ ground surveillance radar BÜR, TerraSAR space radar, and in the Eurofighter’s E-Captor radar.
The SMTRM is a hermetically covered circuit board with the dimensions of 64,5 mm length, a width of 13,5 mm a height of and 4,5 mm. This board contains a power amplifier being in the shape of two monolithically integrated circuits fed with different phaseshift, a ferrite circulator for connection of a transmitter/receiver to the transmit/receive path, a monolithically integrated limiter and a low noise pre-amplifier. The received signal will be downconverted into an intermediate frequency. All circuits are performed in Gallium-Arsenide (GaAs) semiconductor technology.
