# Electromagnetic Performance Characterization and Circuit-Level Modeling of a Miniaturized Meander-Line Antenna for Implantable and Wearable RFID Applications

## TL;DR

This paper presents a small, efficient antenna for biomedical devices that works safely in the body and meets communication and safety standards.

## Contribution

A miniaturized meander-line patch antenna is proposed for implantable and wearable RFID applications with validated performance and safety.

## Key findings

- The antenna achieves a peak gain of 1.29 dBi in free space and -24.99 dBi at 2.45 GHz.
- It has a fractional impedance bandwidth of 250 MHz and meets SAR safety standards.
- Experimental validation in a tissue-mimicking phantom confirmed reliable performance.

## Abstract

This paper proposes a small size meander-line patch antenna which is designed to have biomedical telemetry applications using the Industrial, Scientific and Medical (ISM) band from 2.40 to 2.48 GHz supported by the equivalent circuit model (ECM). Antenna miniaturization is realized by the effective use of several slot structures placed in the rectangular microstrip patch structure, in order to realize electrical length extension and reduce the physical size. The antenna has overall dimensions of 12 × 22 × 0.787 mm3 and is made on a low-loss Arlon AD 450 (εr = 4.50 and tanδ = 0.0035) dielectric substrate, which has the desired stable electrical behavior and, importantly, can be used in implantable environments. Experimental validation is done by implanting the fabricated prototype into a laboratory-manufactured tissue-mimicking phantom, and it showed good agreement with simulated results. The designed antenna has a peak gain of 1.29 dBi in free space and −24.99 dBi at a frequency of 2.45 GHz and a fractional impedance bandwidth of about 250 MHz, which will guarantee reliable operation in the face of diversity and fluctuation in the surrounding environment (biological tissues). Furthermore, specific absorption rate (SAR) analysis is carried out in order to comply with international safety standards with peak SAR values kept within the permissible level of 2 W/kg for 10 g averaging tissue. The results show that the proposed antenna provides a good trade-off between the reduction in size, radiation performance and safety to the patient, making it a good candidate for short-range in-body wireless communication, implantable medical devices, and biomedical monitoring systems.