Spatially fed scanning antennas combine the advantages of optic theory and antenna array technology, exhibiting the capabilities of real-time beam manipulation, flexible structural configuration and low cost. According to the placement of the feeding source, the spatially fed scanning antennas can be categorized into reconfigurable reflectarray antenna (RRA) and reconfigurable transmitarray antenna (RTA). In general, designing RTAs is more challenging due to the simultaneous requirements of low-loss transmission and tunable transmission phase. Despite such design difficulties, RTAs are more applicable to practical engineering application owing to the elimination of feed blockage. In recent years, extensive research has been conducted on various RTAs for a wide range of engineering applications. Nevertheless, existing studies predominantly adopt half-wavelength periodic elements for RTA design, while the potential effects of element period on the radiation performance of RTAs remain rarely explored. This paper investigates the influences and underlying mechanisms of element period on RTA radiation performance under continuous phase compensation and 1-bit quantized phase compensation conditions. The simulated results demonstrate that variations in element period exert negligible effects on the directivity of RTAs adopting continuous phase compensation. In contrast, for RTAs with 1-bit quantized phase compensation, element period reduction can effectively mitigate aperture phase errors and enhance antenna directivity, and this enhancement effect is particularly significant for small-aperture RTAs. Guided by the above conclusions, a miniaturized 1-bit reconfigurable transmitarray element with a period of 0.33λ₀ is proposed through four design procedures, including initial design, period reduction, element decoupling and bias network simplification. Based on a comprehensive analysis of element performance, a rectangular waveguide is utilized to measure and validate the fabricated prototype of the miniaturized element. On the basis of element analysis, a compact RTA is designed with 16×16 miniaturized elements and a planar feed. The overall profile height of the RTA is only 80 mm, equivalent to 2.7λ₀ at 10 GHz. Measured results show that the RTA achieves a realized gain of 18.6 dBi and an aperture efficiency of 20.3% at 10.0 GHz, realizing high aperture efficiency with a small aperture size. In addition, the RTA realizes wide-angle beam scanning from 0° to 60° in both the E-plane and H-plane. When the beam is scanned to 60° in the E-plane, the gain degradation is merely 3.1 dB. Compared with the existing RTAs, the proposed RTA possesses the advantages of compact structure, bias simplification, and favorable radiation performance.