A radiator is formed by forming a multitude of slot antennas adjacent one another such that the spacing between each pair of adjacent slot antennas is smaller than the wavelength of the signal being transmitted or received by the radiator. The radiator achieves high efficiency by reducing the excitation of substrate modes, and further achieves high output power radiation by combining power of multiple CMOS power amplifiers integrated in the radiator structure. Impedance matching to low-voltage CMOS power amplifiers is achieved through lowering the impedance at the radiator ports. Each output power stage may be implemented as a combination of several smaller output power stages operating in parallel, thereby allowing the combination to utilize an effective output device size commensurate with the impedance of the radiator.