The invention relates to an antenna structure for coupling electromagnetic energy between a chip and an off-chip element, including a first resonant structure disposed on or in a chip. The first resonant structure is configured to have a first resonant frequency. The antenna structure also includes a second resonant structure disposed on or in an off-chip element. The second resonant structure is configured to have a second resonant frequency substantially the same as the first resonant frequency. The first resonant structure and the second resonant structure are mutually disposed within a near field distance of each other to form a coupled antenna structure that is configured to couple electromagnetic energy between the chip and the off-chip element. The electromagnetic energy has a selected wavelength in a wavelength range from microwave to sub-millimeter wave. The invention also relates to a method of calculating dimensions for a highly coupled antenna structure.