Opportunities for Antenna Technology to Facilitate SHF and EHF Coexistence and Spectrum Sharing

Radio technology and spectrum policy both were developed in the early <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$20^{\text{th }}$</tex> century when frequencies were much lower and wavelengths much longer than options available today. The smaller wavelengths in SHF and EHF enable antenna approach unimaginable when international and national spectrum polices were first framed. Combined with MIMO-like multielement antenna technology, these antenna approaches can be used to control intersystem and interservice interference to enable novel spectrum sharing approaches that have no analogs in lower bands.