Small Split-Ring Resonators as Efficient Antennas for Remote LoRa IOT Systems-A Path to Reduce Physical Interference

Area of Science:

• Electrical Engineering
• Electromagnetics
• Antenna Design

Background:

• Wireless Internet of Things (IoT) modules require compact antennas, but protruding designs risk mechanical failure.
• Existing antennas can be vulnerable to damage from moving equipment and mechanical stress.

Purpose of the Study:

• To develop a planar antenna using split-ring resonator (SRR) designs for compact IoT modules.
• To achieve antenna dimensions smaller than a monopole at the same operating frequency.
• To evaluate the performance of SRR antennas at LoRa frequencies (433 MHz and 915 MHz).

Main Methods:

• Utilized detailed physical models for printed circuit board (PCB)-based SRR antenna designs.
• Performed uncertainty analysis to assess the impact of tolerances on resonant frequency.
• Conducted near-field and far-field measurements for performance evaluation.
• Integrated an unbalanced SMA port for network vector analyzer measurements of input impedance.

Main Results:

• Developed PCB-based SRR antennas for 433 MHz and 915 MHz LoRa frequencies.
• The optimal design achieved 44 Ω input resistance at 919 MHz, near the target of 50 Ω at 915 MHz.
• Demonstrated a 5 dB gain over a conventional quarter-wave monopole antenna.
• Achieved a 40% smaller footprint compared to the monopole antenna.

Conclusions:

• SRR designs enable the creation of compact, planar antennas for IoT applications.
• The developed antennas provide superior performance and reduced size compared to traditional monopoles.
• This planar antenna technology enhances the robustness and integration possibilities for wireless IoT modules.