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Multiple input multiple output (MIMO) technology combined with orthogonal frequency division multiple access (OFDMA) is an enabling technology used in WiFi 6/6E (IEEE 802.11ax) to increase the throughput. With the addition of WiFi 6/6E and taking advantage of MIMO and OFDMA, many applications of wearable WiFi can be imagined. For example, WiFi can be used for tracking and fall detection. Wearable devices, such as those used in gaming, vital sign monitoring, and tracking, can also take advantage of wearable MIMO antennas. In this paper, a wearable small dual-band antenna is proposed that can be fabricated on felt or denim substrate. In the proposed antenna, a conductive layer is used as a reflector to improve the gain and reduce the sensitivity of the antenna performance to the body loading effects. The details of the design and its performance in a sample indoor MIMO setting are provided. The MIMO antenna is proposed for WiFi tracking and sensing applications. The performance of the MIMO antenna in an indoor setting is examined. [ABSTRACT FROM AUTHOR]

A textile patch antenna is an attractive package for wearable applications as it offers flexibility, less weight, easy integration into the garment and better comfort to the wearer. When it comes to wearability, above all, comfort comes ahead of the rest of the properties. The air permeability and the water vapor permeability of textiles are linked to the thermophysiological comfort of the wearer as they help to improve the breathability of textiles. This paper includes the construction of a breathable textile rectangular ring microstrip patch antenna with improved water vapor permeability. A selection of high air permeable conductive fabrics and 3-dimensional knitted spacer dielectric substrates was made to ensure better water vapor permeability of the breathable textile rectangular ring microstrip patch antenna. To further improve the water vapor permeability of the breathable textile rectangular ring microstrip patch antenna, a novel approach of inserting a large number of small-sized holes of 1 mm diameter in the conductive layers (the patch and the ground plane) of the antenna was adopted. Besides this, the insertion of a large number of small-sized holes improved the flexibility of the rectangular ring microstrip patch antenna. The result was a breathable perforated (with small-sized holes) textile rectangular ring microstrip patch antenna with the water vapor permeability as high as 5296.70 g/m2 per day, an air permeability as high as 510 mm/s, and with radiation gains being 4.2 dBi and 5.4 dBi in the E-plane and H-plane, respectively. The antenna was designed to resonate for the Industrial, Scientific and Medical band at a specific 2.45 GHz frequency. [ABSTRACT FROM AUTHOR]

We present rotational misalignment and bending effects on a hybrid system to transfer power and data wirelessly for an implantable device. The proposed system consists of a high-frequency coil (13.56 MHz) to transfer power and an ultra-high frequency antenna (905 MHz) for data communication. The system performance and the transmitted power were studied under two misalignment conditions: (1) receiver rotation around itself with reference to the transmitter, and (2) bending of the implanted receiver under three different radii. Implanted receiver was printed on a flexible Kapton substrate and placed inside a layered body tissue model at a 30 mm depth. It is shown that the inductive link is stable under rotational misalignment and three bending conditions, whereas the communication data link is suitable to be used if the rotation angle is less than 75° or larger than 150°. The results show that the resonance frequency varies by 1.6%, 11.05%, and 6.62% for the bending radii of 120 mm, 80 mm, and 40 mm, respectively. Moreover, transmission efficiency varies by 4.3% for the bending radius of 120 mm. Decreasing the bending radius has more effects on antenna transmission efficiency that may cause severe losses in the communication link. [ABSTRACT FROM AUTHOR]

In this work, a dual-band printed planar antenna, operating at two ultra-high frequency bands (2.5 GHz/4.5 GHz), is proposed for wireless power transfer for wearable applications. The receiving antenna is printed on a Kapton polyimide-based flexible substrate, and the transmitting antenna is on FR-4 substrate. The receiver antenna occupies 2.1 cm 2 area. Antennas were simulated using ANSYS HFSS software and the simulation results are compared with the measurement results. [ABSTRACT FROM AUTHOR]