A Miniaturized Circularly-Polarized Antenna for In-Body Wireless Communications

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Antenna Theory

Background:

• Implantable antennas are crucial for wireless medical devices.
• Miniaturization and circular polarization are key challenges for implantable antennas.
• Existing antennas often lack sufficient bandwidth or efficiency for reliable communication.

Purpose of the Study:

• To propose a novel miniaturized, single-fed, circularly-polarized microstrip patch antenna.
• To optimize the antenna for implantable wireless communication systems operating in the ISM band.
• To achieve a compact size while maintaining desired polarization and bandwidth characteristics.

Main Methods:

• Utilizing reactive loading in an arrow-shaped slotted patch to induce a slow-wave effect.
• Embedding V-shaped slots within the patch to extend the current path and reduce antenna size.
• Simulating and measuring antenna performance, including impedance bandwidth, axial ratio, and radiation patterns.

Main Results:

• The proposed antenna achieved miniaturized dimensions of 9.2 mm × 9.2 mm × 1.27 mm.
• Left-handed circular polarization (LHCP) was demonstrated through radiation pattern analysis.
• An impedance bandwidth of 7.2% (2.39–2.57 GHz) and an axial ratio bandwidth of 3.7% (2.39–2.48 GHz) were obtained.
• Ex vivo measurements validated the simulated performance.

Conclusions:

• The developed antenna meets the requirements for miniaturized, high-performance implantable wireless communication.
• The design effectively utilizes slotting techniques for size reduction and performance enhancement.
• The antenna shows promise for reliable data transmission in medical implantable devices.