Design considerations for antennas for the millimeter wave bands

The use of the 20/30 GHz band for satellite communication will allow much more freedom in antenna design than has been possible at the lower frequencies. They can be electrically larger even if they are identical mechanically to lower frequency units. This freedom can be used to produce antennas with multiple beams, with contoured beams, and even with multiple, contoured and switchable beams with the associated added freedom in systems design. It will make possible such concepts as "switchboard-in-the-sky" and on-board regenerative systems. To utilize this added degree of freedom will require development of several new technologies.