The array factor (sidelobe level, SLL) of a linear array is optimized using modified continuous genetic algorithms in this work. The amplitudes and phases of the currents as well as the separation of the antennas are all taken as variables to be controlled. The results of the design using modified GA versions are compared with other methods. Two design problems were studied using several contin...

Polyphase is a common class of pulse compression waveforms in the radar systems. Oppermann code is one of the used codes with polyphone pattern. After compression, this code has little tolerant against Doppler shift in addition to its high side lobe level. This indicates that the use of Oppermann code is an unsuitable scheme to radars applications. This paper shows that the use of amplitude wei...

Thinning of large antenna arrays in order to obtain low sidelobes is a difficult and nontrivial problem. Evolutionary programming (EP), a multi-agent stochastic search method, is proposed for optimizing thinned phased arrays with a large number of elements. Experiments are conducted to determine the efficiency of EP procedure in terms of the reliability in producing acceptable solutions and the...

A mainlobe interference suppression method is proposed in this paper, which can still work when the signal of interest (SOI) is present in the training data. In this method, the iterative adaptive approach (IAA) is applied to spatial spectrum estimation at first. Then, IAA spatial spectrum is used to reconstruct the interference-plus-noise covariance matrix (INCM). Next, the eigenvector associa...

This paper describes a new microphone array technique and investigates its effectiveness for speech enhancement. A system structure consisting of a fixed near-field superdirective beamformer and an adaptive sidelobe canceling path is proposed (NFSD-ASC). The effect of adding a post-filter is also examined. The system is evaluated in terms of speech quality measures in the context of a computer ...

It is generally believed genetic algorithm (GA) is superior to particle swarm optimization (PSO) while dealing with the discrete optimization problems. In this paper, a suitable mapping method is adopted and the modified PSO can effectively deal with the discrete optimization problems of linear array pattern synthesis. This strategy has been applied in thinned linear array pattern synthesis wit...

In industry and academia, researchers have given more and more attention to Cognitive Radio (CR). The key idea of CR is to make it possible for a wireless system to find the vacant spectrum and transfer data without interfering with licensed users (LUs). Then, OFDM is proposed as a candidate signaling technology for such applications. However, the sidelobe interference of subcarriers has become...

Three issues regarding sensor failure at any position in the antenna array are discussed. We assume that sensor position is known. The issues include raise in sidelobe levels, displacement of nulls from their original positions, and diminishing of null depth. The required null depth is achieved by making the weight of symmetrical complement sensor passive. A hybrid method based on memetic compu...

This paper introduces a novel variation of the vee dipole antenna consisting of two coplanar vee dipoles with a common feed point. It is referred to as a double-vee dipole. Radiation characteristics of the double-vee dipole antenna are investigated numerically and experimentally. It is shown that the double-vee dipole can provide significantly higher directivity and lower sidelobes and back rad...