Compact Dual-Band Tapered Open-Ended Slot-Loop Antenna For Energy Harvesting Systems

Abstract

In this study, a compact dual-band combined loop-slot planar antenna is proposed. (1) Background: multi-function antennas are desired for wireless communication to cover the desired frequency spectrum. (2) Methods: the proposed antenna consists of a semi-rectangular open-ended loop (OEL) operating at the lower frequency band 920 MHz, an open-ended slot (OES) transmission line that provides resonance at the higher band 2.4 GHz, and a feeding port using the asymmetric coplanar strip (ACS) line. The ACS is used to excite the antenna to achieve dual-band performance. The overall dimensions of the fabricated prototype are 32.5 × 53.5 mm2 (0.1λo×0.16λo), where λo represents the free-space wavelength at the lower frequency. (3) Results: from the calculations, the antenna shows two impedance bandwidths (estimated at −10dB) of 30 MHz (920–950 MHz) and 300 MHz (2.2–2.5 GHz) to cover the ISM band (920 MHz) and 2.45 GHz WiFi bands, respectively. Indeed, the antenna has stable radiation patterns and achieves peak measured realized gain of 1.8 dBi in the lower band and 4.2 dBi in the higher band. (4) Conclusion: the antenna shows the merits of low profile structure, single-layer, and low-cost fabrication. The proposed antenna not only achieves incremental increase in radiation efficiency, but also provides a lightweight, and small footprint.