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Data collection of the radio wave propagation loss in farm fields is valuable to design a wireless network in a farm. They are used in calculating the link budget to establish a proper and efficient node arrangement. In this study, propagation losses in a 50 × 50 m mulberry field were measured in 920-MHz band with respect to the azimuthal angle of the propagation direction to arrays of bushes. Received...
Reflection and radiation characteristics of a slot antenna backed by a half cylindrical cavity made of conductive textiles have been measured. Two conductive textile sheets and conductive threads configured a post-wall structure forming a cavity of a thin half-cylinder. The antenna was designed for the operation frequency around 2.45 GHz. The reflection and radiation characteristics were measured...
Collecting data of propagation losses in farm fields is important to design a wireless network in a farm. They are used in calculating the link budget to establish a proper and efficient node arrangement. In this study, propagation losses in a 50 × 50 m mulberry field were measured in 920-MHz and 2.4-GHz bands. Received signal strength indicators (RSSIs) were measured as a function of the distance...
Efficient operation of a wireless power transfer (WPT) system is a major design challenge in many WPT applications. This paper presents a method for designing a high efficiency WPT system when restrictions are imposed on receiver coil (Rx) size. The optimum pitch of the transmitter (Tx) and Rx coils is evaluated by analyzing the coil quality factor and coupling coefficient. Empirical formulae are...
A flexible textile antenna has been fabricated using a polyester fabric as a substrate of the feed line to the antenna and studied in bending cases. The antenna is a cavity-backed slot antenna (CBSA) made of conductive textiles. The substrate of the feed line is also a textile sheet rather than conventional material in order to make the antenna more flexible. Moreover, the feed line is fixed by sewing...
RFIDs in the UHF band are getting popular gradually in a lot of situations. Many kinds of small antennas have been contrived for UHF RFIDs. However, the antenna characteristics deteriorates in the case of using the antenna around water. In this report, a small cylindrical antenna was designed, which has little effect of water. The antenna is fed from an excitation loop outside of the radiation loop...
Near-field coupling communication (NFCC) is a technology that uses the surface area of the human body as a communication path using the megahertz band. We have already evaluated the basic mechanism connected with NFCC on a phantom that was electrically regarded as a human body. The shape of the human body was not considered in the evaluation since the shape of the phantom was simply rectangular and...
Effects of the deformation in the cavity of a flexible cavity-backed slot antenna on its reflection and radiation characteristics have been analyzed and compared with the measured ones. The antenna is a slot antenna backed by a hollow cavity made of a conductive textile and can be bent along a spherical surface. It is designed for the operation frequency around 2.4 GHz. The frequency characteristics,...
The loss characteristics of radio propagation in 920-MHz band in a farm were investigated. An experiment was carried out in a mulberry field of the area of 50 m × 50 m in order to obtain fundamental data of the path loss in the field. Received Signal Strength Indicator (RSSI) according to the distance between the transmitting antenna (Tx) and the receiving antenna (Rx) was investigated. Tx was placed...
A flexible textile antenna has been fabricated using a polyester fabric as a substrate of the feed line to the antenna and studied in bending cases. The antenna is a cavity-backed slot antenna (CBSA) made of conductive textiles. The substrate of the feed line is also a textile sheet rather than conventional material in order to make the antenna more flexible. The reflection characteristics in around...
The equivalent circuit of a slot antenna and the feed line was studied for the reflection characteristics depending on the tuning parameters. The antenna was a cavity-backed slot antenna and fed with a microstrip line by electromagnetic coupling. The previously proposed equivalent circuit was used to calculate the reflection coefficients depending on the tuning stub and offset lengths of the feed...
Near-field coupling communication (NFCC) is a technology that uses the surface of the human body as a transmission path in the MHz band. It is necessary to assess the signal loss on the body to ensure stable NFCC links. The dependence of signal loss on different positions on the body was measured with a transmitter powered by a battery and an electrically isolated probe as a receiver. The electric-field...
The change of the radio wave propagation loss in 920-MHz band was examined as bushes in a farm grew higher. Received Signal Strength Indicator (RSSI) was measured as a function of the distance between the transmitting antenna (Tx) and the receiving antenna (Rx) in a 50 × 50 m mulberry field. Tx and Rx were placed at a height of 1.5 m. Moreover, the horizontal and vertical polarizations were measured...
We developed a near-field coupling communication (NFCC) technology that uses the surface of the human body as a data transmission path in the MHz band. It is important to assess the loss of signal propagation on the human body to design a “touch and connect” form of stable NFCC links. We measured the signal propagation characteristics on a phantom equivalent to the human body with an electrically...
A flexible cavity-backed slot antenna has been improved by using a post-wall structure. Arrays of conductive threads as vias between two conductive sheets of textiles are forming post-walls of the rectangular cavity. The reflection and radiation characteristics of the slot antenna have been measured for the flat case and the case of being bent. This type of antenna is flexible and wearable, so it...
In this paper, an equivalent circuit is newly described for a cavity-backed slot antenna considering the feeder and the slot element. The slot antenna has employed an electromagnetic coupling, so no solder or conductive adhesive is used. The slot is treated as a distributed constant line with a short-circuited termination, and a tuning stub is treated as a distributed constant line with an open termination...
3. 3 Gbps × 3TDM IR signal transmission in combined 10 km SMF and wireless link with UWB band of 7.25–10.25 GHz is demonstrated. We proved the generation of quasi-Nyquist IR-UWB signal from optical RZ pulse.
The reflection and radiation characteristics of a cavity-backed slot antenna fabricated of a conductive textile have been studied. The operation frequency is about 2.3GHz, and the variation in the characteristics is evaluated when the antenna is bent. The bending shape is spherical while the cylindrical bending case was reported previously. The excitation of the antenna is performed by an electromagnetic...
We studied MHz-band communication between a TRX on the surface of the human body (wearable TRX) and a TRX embedded in the environment (embedded TRX). In this work, we propose a medical application to take advantage of MHz-band characteristics on the human body by embedding a TRX into the human body (in-body TRX) and examined the feasibility of in- and on-body communication. We also fabricated an electrically...
The reflection and radiation characteristics of a cavity-backed slot antenna fabricated of a conductive textile have been measured. The operation frequency is about 2.2GHz, and the variation in the characteristics is evaluated when the antenna is bent. The bending direction is tried in two forms. The excitation of the antenna is performed by an electromagnetic coupling, so no solder or conductive...
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