The objective of the proposed research is to develop highly integrated interposers with embedded dies and thin film components such as antennas at sub-THz frequencies for the next generation 6G applications. The focus is on handsets that feature back-end high-speed processing for applications such as on-device AI. AI applications require specialized chips that need to communicate with each other through interconnections. Our focus here is to demonstrate high-speed communication between chips through non-TSV based integration in glass interposer. 3D+ integration is proposed for the integration of RF and baseband ICs in glass interposer with antennas to achieve a compact profile and low insertion loss between the chips. The proposed packaging architecture features both embedded chips and flipchips on glass interposer with short, vertical, high-bandwidth interconnects between the chips. Chip-to-interposer and chip-to-chip transitions in the proposed integration technology is modeled and characterized using specially designed test structures. The challenges with direct characterization of the individual transition are addressed by introducing a characterization method that uses multiple back-to-back transitions to extract the S-parameters of an individual transition. A broadband S-parameter characterization from near-DC to 170 GHz of such interconnects is presented, using which eye diagram simulation have been performed to predict the maximum data rate and the bandwidth density supported. This work also discusses the design and characterization of integrated high-bandwidth end-fire antennas on glass interposer in D-band. Characterization of antennas operating at frequencies over 100 GHz entails challenges due to the unavailability of the coaxial cables at these frequencies. This work aims to address this problem by exploring probe-station-based methods of end-fire antenna characterization without using expensive characterization facilities that require robotic arms and custom assemblies.