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In this paper, a pulse shifting approach with phase-only weighting is proposed for a cosecant-squared radiation pattern time-modulated linear array (TMLA) synthesis. The sidelobe level (SLL) of fundamental signal and maximum sideband levels (SBLs) of harmonic signals is simultaneously reduced. This is achieved by controlling both the phase and the periodic switching time sequence of each element of the TMLA. In pulse shifting, the on–off switching sequence of each radiating element is characterized by a switch-on instant and interval within the modulation period which increases the degrees of freedom. A genetic algorithm (GA) is employed to optimize the switch-on and switch-off instants of each time pulse along with the phase weight for each element in the antenna array. The simulation results reveal that the proposed method can achieve the required patterns with very low SLL and SBLs. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for synthesizing multiple radiation patterns with reduced hardware complexity in the feed network by exploiting the additional degree of freedom ‘time’ in time modulated unequally spaced linear array (TMUSLA) is presented. In the proposed approach, with a suitable common set of element position of TMUSLA, the desired dual-beam pattern with low sidelobe level (SLL) is obtained by simply controlling the ON-OFF time sequence of the RF switches connected to the array elements. To show the effectiveness of the proposed array synthesis method, two dual beam patterns - first one as pencil (sum) beam (PB) and flat-topped beam (FTB) pattern, and the second one as sum and difference pattern with different constraints have been synthesized. For the successful generation of the desired power patterns, differential evolution (DE) algorithm is employed to obtain the optimum possible solution in terms of common element position, time-modulation, switching sequences and applicable excitation phase for the desired shape beam patterns. The superiority of the proposed approach with the favourable improved performance have been demonstrated by comparing the realized patterns with the state-of-the-art relevant reported works.

A novel method of designing unequally spaced time-modulated arrays (UESTMAs) by handling fewer optimization parameters with reduced problem dimension is presented in this paper. For synthesizing UESTMA, two design parameters, specifically, the non-linear parameter - element position, and the linear parameter – on-time durations are optimized in two steps. Different possible cases of linear and non-linear synthesis methods such as, position-only (PO), on-time only (OTO), position then on-time (PTOT), on-time then position (OTTP), and simultaneous position on-time (SPOT) are considered. To examine the performance of the synthesis methods, three global search stochastic algorithms based on differential evolution (DE), teaching-learning-based optimization (TLBO) and quantum particle swarm optimization (QPSO) have been employed to achieve the array pattern with significantly suppressed side lobe levels and sideband levels. Through comparative study, it is observed that the two step non-liner to linear synthesis method by fewer optimization parameters is efficient to provide better pattern with less computation time.

In this paper, a novel approach for synthesizing multiple radiation patterns with reduced hardware complexity in the feed network by exploiting the additional degree of freedom 'time' in time modulated unequally spaced linear array (TMUSLA) is presented. In the proposed approach, with a suitable common set of element position of TMUSLA, the desired dual-beam pattern with low sidelobe level (SLL) is obtained by simply controlling the ON-OFF time sequence of the RF switches connected to the array elements. To show the effectiveness of the proposed array synthesis method, two dual beam patterns - first one as pencil (sum) beam (PB) and flat-topped beam (FTB) pattern, and the second one as sum and difference pattern with different constraints have been synthesized. For the successful generation of the desired power patterns, differential evolution (DE) algorithm is employed to obtain the optimum possible solution in terms of common element position, time-modulation, switching sequences and applicable excitation phase for the desired shape beam patterns. The superiority of the proposed approach with the favourable improved performance has been demonstrated by comparing the realized patterns with the state-of-the-art relevant reported works. [ABSTRACT FROM AUTHOR]

A novel method of designing unequally spaced time-modulated arrays (UESTMAs) by handling fewer optimization parameters with reduced problem dimension is presented in this paper. For synthesizing UESTMA, two design parameters, specifically, the non-linear parameter - element position, and the linear parameter - on-time durations are optimized in two steps. Different possible cases of linear and non-linear synthesis methods such as, positiononly (PO), on-time only (OTO), position then on-time (PTOT), on-time then position (OTTP), and simultaneous position on-time (SPOT) are considered. To examine the performance of the synthesis methods, three global search stochastic algorithms based on differential evolution (DE), teaching-learning-based optimization (TLBO) and quantum particle swarm optimization (QPSO) have been employed to achieve the array pattern with significantly suppressed side lobe levels and sideband levels. Through comparative study, it is observed that the two step nonliner to linear synthesis method by fewer optimization parameters is efficient to provide better pattern with less computation time. [ABSTRACT FROM AUTHOR]

In this work, the maximum point of relative sideband level (SBL) with respect to maximum level of main radiation (the radiation in carrier frequency) in time-modulated linear and planar arrays is examined. An inequality is derived which may be used for the determination and suppression of maximum relative sideband level. Performance analysis in terms of sideband level, harmonic power loss, directivity and feed network efficiency are conducted with state of the art methods to compare and to demonstrate the potential of the presented formulation for linear and planar cases. [ABSTRACT FROM PUBLISHER]