Conventional passive metamaterials always suffer from the limitation of loss and dispersion due to fundamental causality issue. Especially it becomes severe due to material loss at terahertz frequency. Our work resolves the loss problem by introducing gain device into the metamaterial structure. A passive volumetric metamaterial is firstly designed on the quartz substrate. A negative resistance is inserted into the wire of the structure to provide the gain. We have identified resonant tunneling diodes that work up into THz frequency and shown in simulation that simultaneous negative index and gain can be obtained.

This dissertation focuses on the development of next generation wireless communications at millimeter-wave and sub-terahertz frequencies. As wireless providers experience a bandwidth shortage and cellular subscribers demand faster data rates and more reliable service, a push towards unused carriers fre- quencies such as 28 GHz, 60 GHz, and 180 GHz will alleviate network conges- tion while simultaneously providing massive bandwidths to consumers. This dissertation summarizes research in understanding millimeter-wave wireless propagation, the design and fabrication of millimeter-wave and sub-terahertz on-chip antenna arrays on an integrated circuit semiconductor process, and the accurate measurement of on-chip antenna radiation patterns in a wafer probe station environment. / text