A direct-coupled technique for standing wave oscillator (SWO) arrays is presented in this paper. The oscillation currents of a unit cell in the SWO array directly inject to adjacent cells through the resonator. Two 2-D SWO arrays based on the technique are reported. The first SWO array can provide synchronous signals with identical frequencies, amplitudes, and phases at multiple locations over a chip. It is implemented in a 90-nm CMOS technology with 61.5-GHz oscillation frequency. Millimeter-wave radiators that consists of the proposed SWO array, an RF driver array, and an on-chip loop antenna array are implemented in a single chip to verify the synchronicity of the reported 2-D SWO via wireless measurement. The indirect evidence of synchronicity is provided from the correlation between the wireless measured effective isotropic radiated power (EIRP) and phase noise of 1 x 1, 2 x 2, and 3 x 3 arrays. The EIRP in the normal direction of the array is increasing by a factor of 10 log N-2 and the phase noise is reducing by a factor of 10 log N over that of a single cell, where is the number of unit cells in the array. The second SWO array can provide synchronous signals with identical frequencies, amplitudes, and multiple phases at multiple locations over a chip. It is implemented in a 65-nm CMOS technology with 132.5-GHz fundamental frequency. The SWO array is designed for a 2-D second-harmonic (265 GHz) spatial power radiating and combining array. The EIRPs of the fundamental frequency and second harmonic in the normal direction of the array are -34 and -6.5 dBm, respectively. The phase noise of the fundamental frequency and second harmonic at 1-MHz offset from the carrier frequency are -96 and -89 dBc/Hz, respectively.