Considerations of Dielectric Property Deviation and Mechanical Limitations for Antenna-in-Package Fabrication by SiP-Based Stacked Organic Dielectric Substrates at Millimeter-Wave Frequencies

Wireless communications at millimeter-wave (mmW) frequencies suffer high propagation loss and low energy efficiency. The feeding circuits in dielectric substrates may also result in antenna excitation distortions in both phases and amplitudes. Antenna-in-package (AiP) integrating active RF transceivers is considered a reliable means to shorten RF circuit path lengths and connectors to enhance user equipment (UE) antennas' radiation characteristics. However, due to the several mechanical limitations and fabrication uncertainty at mmW frequencies, AiP implementation should better consider geometric parameter effects, which may degrade its radiation performance, to reduce beamforming complexity for easy design and low-cost fabrication. Besides, by taking advantage of active RF transceiver modules to provide output amplitude ratios and phase variations, the feeding circuits can be simplified to shorten the feeding microstrip line lengths. These effects are examined and presented in this article for a practical design of an AiP fabricated for validation by comparing full-wave simulations and measurement results. Simulations and measurements also validate using the calibration technique to simplify the feeding structures to demonstrate the feasibility.