Radiation Efficiency-Improvement Using a Via-Less, Planar ZOR Antenna for Wireless ECG Sensors on a Lossy Medium

The critical issues involving severe radiation efficiency degradations during wireless electrocardiogram (ECG) health monitoring sessions are addressed by devising a monolithic zeroth-order resonance (ZOR) antenna. The presented antenna consists of a composite right/left-handed (CRLH) structure that is realized on a single, planar surface of the flexible printed circuit board (PCB) without the use of any via-holes. This significantly alleviates the complexity and fabrication cost involved with vertically polarized antennas with monopole-like radiation patterns, which are important factors in consumer electronics. Moreover, this letter investigates the practical issues associated with effects of the in-house designed ECG device circuit board, feeding mechanism with the RFIC, as well as the polycarbonate chassis. The finalized antenna is less than 0.12λ×0.08λ in total horizontal dimension with zero height profile. Measurement confirms the presented antenna features more than 30% radiation efficiency across 80 MHz bandwidth when completely integrated within the ECG sensor device and placed on the human body phantom.