Wideband multi‐beam forming method using delayed array sensors and two‐dimensional digital filter

Abstract

SUMMARYIn this paper, a method is proposed for multi-beam forming of wideband signals by means of delay processors and two-dimensional fan filters. Only one axially symmetric two-dimensional fan filter is used. Multi-beam forming is carried out by multiplexing the delay processors for two-dimensional signals for each beam direction. The delay processing here corresponds to a rotation of the two-dimensional spectra in the two-dimensional frequency domain and provides a delay proportional to the sensor location to each sensor output. Since each delay is a fractional delay, a method of digital signal processing based on high-speed sampling and thinning is used for realization. A design method for multi-beam forming is given and a study of expanding the receiving angle range is carried out. It is shown that excellent multi-beam forming is possible if the method is used within an appropriate receiving signal range, although the beam width is slightly different depending on the beam direction. Finally, a difference of the method from multi-beam forming by the use of several two-dimensional fan filters is discussed. The positioning of this method and its effectiveness are clarified.

Multibeam Wideband Transmit Beamforming Using 2D Sparse FIR Trapezoidal Filters

“…Fullwave electromagnetic simulations using real antenna models confirm that the proposed wideband transmit beamformer can achieve multibeam transmission in the frequency range of 1.3-2.8 GHz, with more than 70% fractional bandwidth. Importantly, the proposed transmit beamformer provides considerable reduction in the computational complexity compared with nonsparse filter-and-sum transmit beamformers [34][35][36], 2-D nonsparse FIR filters [37][38][39][40][41][42], and 2-D sparse FIR filter [32], without deteriorating beam directionality and causing increases in the side-lobe level. Furthermore, the computational efficiency of our sparse FIR filter design makes them suitable for real-time beamforming applications in wideband systems, while the linear phase response within the passband of the filter contributes to maintaining signal fidelity during beam steering.…”

Radar wideband digital beamforming based on time delay and phase compensation

“…This method has the significant drawbacks of nonreal-time processing and a discontinuous phase. An alternative method of wideband beamforming is to place a tapped delay line or finite impulse response (FIR) filter at the output of each antenna element (Liu & Weiss, 2009;Nishikawa, 2005). As the signal bandwidth increases, more and more taps per antenna element are required to retain the maximum signal-to-interference-plus-noise ratio performance.…”