Optical antennas play a pivotal role in interfacing integrated photonic circuits with free-space systems. Designing antennas for optical phased arrays ideally requires achieving compact antenna apertures, wide radiation angles, and high radiation efficiency all at once, which presents a significant challenge. Here, we experimentally demonstrate a novel ultra-compact silicon grating antenna, utilizing subwavelength grating nanostructures arranged in a transversally interleaved topology to control the antenna radiation pattern. Through near-field phase engineering, we increase the antenna’s far-field beam width beyond the Fraunhofer limit for a given aperture size. The antenna incorporates a single-etch grating and a Bragg reflector implemented on a 300-nm-thick silicon-on-insulator (SOI) platform. Experimental characterizations demonstrate a beam width of $44°\times 52°$ with $-3.22\mathrm{dB}$ diffraction efficiency, for an aperture size of $3.4\mathrm{\mu m}\times 1.78\mathrm{\mu m}$. Furthermore, to the best of our knowledge, a novel topology of a 2D antenna array is demonstrated for the first time, leveraging evanescently coupled architecture to yield a very compact antenna array. We validated the functionality of our antenna design through its integration into this new 2D array topology. Specifically, we demonstrate a small proof-of-concept two-dimensional optical phased array with $2\times 4$ elements and a wide beam steering range of 19.3º × 39.7º. A path towards scalability and larger-scale integration is also demonstrated on the antenna array of $8\times 20$ elements with a transverse beam steering of 31.4º.