Compact high-Q Slot Loaded Dielectric Resonator Filtering Antenna for LoRa applications

High-Q antennas are highly sought after for their narrow bandwidth and compact size, enabling them to occupy minimal volume in a given structure. In this paper, we present a new ultra-narrow band filter/antenna designed for LoRa applications. The filter/antenna consists of an elliptical slot loaded with a high permittivity rectangular dielectric resonator, excited by a coupled microstrip line. The proposed antenna serves not only as a radiating element but also as a filter, offering the significant benefit of eliminating loss between the filter and the antenna. To assess the influence of the SMA power cable on miniature antennas, we conducted a comparison of the antenna with and without a radio frequency (RF) module, focusing on radiation pattern. Our proposed filter/antenna provides a compact profile of 25 × 40 mm2 (λ/13×λ/8), an omnidirectional radiation pattern, and remarkable rejection in the stop-band. The validity of the proposed design is accomplished by comparing the electromagnetic simulation with fabrication and measurement results, achieving a high level of agreement between simulation and measurement. Thanks to its exceptional performance, small size, low cost, and low-power characteristics, this innovative structure is suitable for IoT applications at UHF band with a stop-band outside this frequency to avoid potential interference from adjacent bands.