A multibeam subarrayed time-modulated linear array

Abstract

In conventional time-modulated arrays (TMAs), because of the usage of the RF-switch, harmonics are generated at multiples of the modulation frequency. In this study, the synthesis of time-modulated arrays has been analyzed for cognitive radio (CR) systems, in which these harmonics are suitably exploited for more efficient utilization of the spectrum. In order to accomplish the desired pattern at requested harmonic frequencies, a new excitation strategy with sinusoidal signals is proposed. The use of sinusoidal waveforms creates independent beams, allowing independent steering capability. Moreover, by utilizing the subarray structure, it is possible to have a smaller number of excitation functions in the hardware. It is shown by means of explanatory examples that the effectiveness of the proposed approach is due to free-adjustable beamforming, beam steering, and low complexity.

Dot‐shaped transmit beamforming with nonuniform time‐modulated concentric circular frequency diverse array

“…Recently, there have been several studies using the time-modulated array (TMA) strategy for dot-shaped beamforming. These studies take advantage of the single harmonic beamforming [25][26][27][28] and nonuniform radio frequency (RF) switching features of TMA. [29][30][31] In Maneiro-Catoira et al, 32 FDA employs switched TMAs instead of a variable phase shifter (VPS) and nonuniform Kaiser window-based frequency offsets.…”