This paper presents the design, fabrication, and evaluation of a compact, dual-polarized, wideband, sub-THz frequency-diverse antenna with a novel distributed feed configuration and cross-slot radiation elements implemented by silicon-micromachining. The distributed feed is based on a spiral-shaped waveguide network with multiple Morenocross-couplers for stimulating the overloaded resonance cavity backing the antenna with 140 cross-slot radiation elements optimized for 16 frequencies, which generates pseudo-random radiation patterns over the full waveguide bandwidth of 220–330GHz, with applications to sub-THz imaging. As experimentally verified by comparisons of prototype devices, one with the novel distributed feed and a reference design with an optimized conventional direct feed, the novel feed design reduces the radiation pattern dependence over frequency by at least 48.5%, and up to 83.4%, over the entire frequency range. This clearly demonstrates the effectiveness of the novel distributed feed structure and implies, to a sub-THz imaging system, an improvement of the resolution or a reduction of the necessary number of measurements. Additionally, the distributed feed significantly improves the spatial coverage of the radiation patterns, as demonstrated in the paper. The overall design is very compact, with an active volume of 11×11×0.85λ3c, including the cavity, and the distributed feeding network. The measured return loss of the antenna with the distributed feed is better than 10 dB across the operating bandwidth.