Real-World Performance of Sub-1 GHz and 2.4 GHz Textile Antennas for RF-Powered Body Area Networks

Abstract

In Radio Frequency (RF)-powered networks, peak antenna gains and path-loss models are often used to predict the power that can be received by a rectenna. However, this leads to significant over-estimation of the harvested power when using rectennas in a dynamic setting. This work proposes more realistic parameters for evaluating RF-powered Body Area Networks (BANs), and utilizes them to analyze and compare the performance of an RF-powered BAN based on 915 MHz and 2.4 GHz rectennas. Two fully-textile antennas: a 915 MHz monopole and a 2.4 GHz patch, are designed and fabricated for numerical radiation pattern analysis and practical forward transmission measurements. The antennas' radiation properties are used to calculate the power delivered to a wireless-powered BAN formed of four antennas at different body positions. The mean angular gain is proposed as a more insightful metric for evaluating RFEH networks with unknown transmitter-receiver alignment. It is concluded that, when considering the mean gain, an RF-powered BAN using an omnidirectional 915 MHz antenna outperforms a 2.4 GHz BAN with higher-gain antenna, despite lack of shielding, by 15.4× higher DC power. Furthermore, a transmitter located above the user can result in 1× and 9× higher DC power at 915 MHz and 2.4 GHz, respectively, compared to a horizontal transmitter. Finally, it is suggested that the mean and angular gain should be considered instead of the peak gain. This accounts for the antennas' angular misalignment resulting from the receiver's mobility, which can vary the received power by an order of magnitude.INDEX TERMS Antennas, Body Area Networks (BAN), electronic textiles, energy harvesting, Internet of Things, ISM bands, RF energy harvesting, wearable antenna, wireless power transfer.

Dual-Band Dual-Mode Textile Antenna/Rectenna for Simultaneous Wireless Information and Power Transfer (SWIPT)

“…The antenna design process is divided into two parts: the design of a 50Ω 2.4 GHz antenna with broadside off-body radiation patterns, and the design of a broad-beam sub-1 GHz rectenna, due to the improved harvesting probability an omnidirectional antenna in sub-1 GHz bands [40]. Furthermore, sub-1 GHz rectifiers typically achieve a higher PCE [1].…”

Design and Evaluation of a Flexible Dual-Band Meander Line Monopole Antenna for On- and Off-Body Healthcare Applications

“…BCWC has to work near the human body; therefore, the wearable antenna must meet certain requirements such as being planar, compact, and flexible, and it should be able to easily be integrated with electronic systems and maintain a reliable link while not causing any discomfort for the user. The human body is a hostile environment for an antenna due to the coupling and absorption of the EM waves [ 3 ]. Wearable antennas must be designed and characterized carefully in order to maintain a reliable communication link even under the detuning effects of lossy body tissues, because the human body can deteriorate the performance of the antenna [ 4 ].…”

Waveform Optimization Using RF Pulse Signal on Voltage-Doubler Broadband Rectenna

“…V-D. Pham, H. Takhedmit and L. Cirio are with ESYCOM, Univ. Gustave Eiffel, CNRS UMR 9007, F-77454 Marne-la-Vallée, France (email: hakim.takhedmit@u-pem.fr) Different type of large band or multi-band rectennas and their designing procedures are presented in [12][13][14][15][16][17][18][19][20]. A dual band rectenna operating at 2.4 and 5.8 GHz [13] and rectenna arrays [14][15] are designed to enhance RF energy harvesting applications.…”

“…The rectenna-array is dedicated for harvesting power in the range 4-130 μW/cm 2 between 2 and 5 GHz. An RF-powered Body Area Network, based on 915 MHz and 2.4 GHz rectennas, with multiple power receivers, based on fullytextile antennas is studied in [18]. In [19], the authors use an optimization algorithm to automatically take the output voltage as feedback for system calibration.…”