Improved Resolution for a 1-Bit Transmitarray in Near-Field Focusing Applications

We introduce a novel approach for enhancing the resolution of conventionall-bit transmitarrays (TAs) by utilizing space-time coding technology. Conventional l-bit TAs suffer from the relatively large focal spot due to the phase quantization issue. In this study, space-time modulation technology is introduced with the emergence of spatial harmonic components. By introducing a time delay index to the + 1 st harmonic wave, a continuous phase compensation could be achieved without impacting the original amplitude distribution, thereby achieving a smaller focal spot. Moreover, as the element number reduces (e.g., from $16\times 16$ to $12\times 12,8\times 8$ , and further to $a 6\times 6$ array), the contrast between the near-field focal spots of the conventional l-bit TA and its + 1 st harmonic wave becomes increasingly pronounced. This method holds potential for low-cost and high-resolution imaging applications.