Additive-Free Aqueous Cold Sintering of Tin Fluoride Dielectric Resonator Antennas for the 5G n79 Band

The significant upsurge of 5G devices has triggered the exploration of the bands, n78 and n79, to support high data rates and better connectivity. Antennas are recognized as the essential components of wireless communication systems, so this study mainly focuses on a simple microstrip line-fed, fluoride-based cylindrical dielectric resonator antenna (CDRA) for 5G communication, especially in the n79 band. The deployment of ceramic materials in microwave applications demands the fulfillment of certain criteria, such as low dielectric loss, low and stable relative permittivity, and a high relative density. In this study, we report a single-step densification of SnF2 with moderate relative permittivity (21.4 at 5 GHz) and low loss (∼10–3 at 5 GHz) at 150 °C through the cold sintering process (CSP) using water as the transient liquid phase. X-ray diffraction and vibrational spectroscopic analysis confirmed the phase purity of cold-sintered SnF2. Additionally, microstructural analysis reveals that the low melting point of tin fluoride (216 °C) offers an additional partial melting mechanism, along with compaction and dissolution–precipitation, for the high relative density of 98%. The parametric analysis shows how the performance of the cold-sintered CDRA varies with the overlapping distances. Furthermore, a prototype operating at the n79 band was realized using the optimized structure and tested inside an anechoic chamber, exhibiting comparable antenna properties such as the resonance frequency, impedance bandwidth, voltage standing wave ratio (VSWR), and far-field radiation patterns. The prototype resonates at 4.67 GHz with an S11 of −37.8 dB, a VSWR of 1.06, an impedance bandwidth of 430 MHz, and a boresight radiation pattern with a 5.5 dB gain. The radiation pattern, gain analysis, and comparative study of simulated as well as experimental antenna parameters suggest that the cold-sintered antenna can find applications in n79 band 5G communications.