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This paper illustrates the use of active frequency selective surfaces (FSS) in reconfigurable antennas. A patch-form dual-polarized tunable FSS is adapted for use as an active artificial magnetic conductor (AMC). As with the tunable FSS, the active AMC offers independent tuning capability of the reflection phases for two polarisations of incident EM waves. By combining the AMC with a wideband coplanar...
This paper presents a frequency and polarization reconfigurable circular polarized (CP) antenna using active artificial ground (AG) structure. The active AG structure offers independent and symmetrical tuning capability of the reflection phases for dual polarized incident waves. By combining the AG structure with a wideband coplanar waveguide fed monopole antenna, and tuning the capacitances of the...
Two passive sensing designs based on UHF RFID technology are presented for assisted living application. The first tag is mounted on the hard palette of the mouth and detects tongue position, while the second is a skin-mounted strain gauge. Both designs are proposed for wheelchair or computer mouse control applications. Measurements show the sensors can communicate over short ranges comparable with...
The issues of fabricating transfer RFID tags for epidermal application are discussed in terms of achievable ink conductivity, thickness and performance in the presence of minor printing defects.
Body area networks are complex to analyze as there are several channel mechanisms occurring simultaneously, i.e. environmental multipath together with body motion and close coupling between worn antennas and human tissue. Electromagnetic (EM) simulation is an important tool since not all studies can be done on a real human. In order to gain insight into off-body communication involving a worn antenna,...
RFID tags are integrated into medical sticking plasters for future health monitoring applications. For compatibility with the skin, the tag is fabricated from conducting Electronylon material and is demonstrated to work with a useful read range when placed directly on the skin. For the purposes of this study, a useful read range was defined as more than 50cm.
Body-worn physiological sensors can facilitate ambulatory patient monitoring, particularly if communication between sensors is wireless; but the communication channel must be robust. This paper presents how a 3D animated human model is created using a 3D scanner and a motion capture system. Then this model is used in XFdtd, electromagnetic simulation software to obtain body worn channel properties...
This paper studies the integration of wearable antennas and high impedance surface on ceramic body armor plates. It analyses the performance of wearable antennas on ceramic body armor plates and the use of bullet-resistant ceramic plates as dielectric for high impedance surfaces (HIS). The ceramic ballistic plate employed is a typical ceramic level 3 small arm protective insert (SAPI) used by the...
A switchable frequency selective surface (FSS) made of square loop slots and PIN diodes connected to a novel separate biasing circuit is presented. The structure uses a very thin, flexible substrate sandwiched between two physically independent metallic layers to create the active filter. An application is the modification of the EM architecture of buildings, where propagation could be controlled...
This paper describes the performance of high impedance surfaces (HIS) integrated into body armour equipment. A protective insert made of Aramid material and a metallic woven layer is used as the dielectric material with a metallic ground plane of the HIS. The frequency selective layer added to create the high impedance surface consists of a 15×15 array of interwoven spiral elements capable of reducing...
This paper introduces a technique for simultaneous dual-band operation of a slot based frequency selective surface (FSS). The dual-band function is achieved by the inclusion of series-resonant tuned circuits positioned at each slot centre, therefore functioning as a passive frequency selective switch. A surface offering pass-bands in the WLAN bands of 2.45 and 5GHz is presented and its performance...
A novel temporary transfer tattoo based RFID tag is presented providing a non-optimised read range of 50cm. The transfer based tag is proposed for security and personnel tagging applications where the injection of a sub-skin tag is not desirable. With some refinement the tag could have a life span of a day or more, but could not be transferred to another person without destroying it. By applying correctly...
An animated human model to be used in an electromagnetic simulation software, XFdtd, has been created using a 3D scanned surface of a real person combined with body movement data captured from a motion capture system. Investigations are carried out to verify the accuracy of the human body simulation for different mesh sizes. A study of the effect of body position over an on-body radio channel is also...
This paper introduces resonant “traps” and their potential uses to frequency selective surfaces (FSS). A trap can be considered a passive frequency selective switch offering a high or low impedance state depending upon operating frequency. The paper illustrates an established trap application and introduces the potential for use in FSS designs. A harmonically or near harmonically related dual-band...
This paper addresses the antennas design for passive UHF RFID applications involving the human body as the object to be tagged. Novel antenna geometry is proposed for conjugate impedance matching to the complex impedance of the RFID transponder. The proposed tag is capable of achieving high read range directly attached to a human thorax or in free space.
The field structure on individual elements of a finite 3×3 double layer FSS for long wavelength is measured in the near field. The transmitted fields are compared at different frequencies and non-uniformities in individual element excitations at different points in the array are observed as indications of finite edge effects in an electrically small array.
Deploying wireless systems so that they offer the best performance for all stakeholders (e.g. users, service providers and shareholders) is identified as a critical issue in advancing the wireless industry into the second decade of the twenty-first century. An historical perspective of the key issues is initially presented, from which a set of societal expectations of future wireless performance are...
In this paper, a slot antenna on a textile integrated waveguide is presented. Denim has been employed as the substrate filling the waveguide containing the antenna. The intention is to use the antenna as part of the clothing, where there is sufficient space to accommodate large devices but there are limitations in the thickness of the outfit. The antenna design proposed aims to be mounted into a belt...
Designers of civil communications systems face an increasing strain on the radio frequency spectrum as demand increases. Much high speed data access is required indoors and it is therefore reasonable that future buildings should be designed with wireless communications systems in mind. Buildings could be equipped to offer a controlled propagation environment with isolation of secure data and blocking...
The unit-cell size needed for operation at a given frequency can be reduced dramatically by using highly convoluted and interwoven elements. The dual-polarized designs presented here are based on convoluted loops. The geometry of the convoluted square loop provides a further degree of flexibility in wideband design, enabling adjacent elements to be interwoven. Here, interweaving decreased the resonant...
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