Flexible and Compact AMC Based Antenna for Telemedicine Applications
TL;DR: Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas, which makes it a good candidate for the wearable telemedicine application.
Abstract: We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application.
Citations
More filters
TL;DR: The fundamental building blocks of an FHE system, printed sensors and circuits, thinned silicon ICs, printed antennas, printed energy harvesting and storage modules, and printed displays, are discussed and the recent progress, fabrication, application, and challenges, and an outlook, related to FHE are presented.
Abstract: The performance and integration density of silicon integrated circuits (ICs) have progressed at an unprecedented pace in the past 60 years. While silicon ICs thrive at low-power high-performance computing, creating flexible and large-area electronics using silicon remains a challenge. On the other hand, flexible and printed electronics use intrinsically flexible materials and printing techniques to manufacture compliant and large-area electronics. Nonetheless, flexible electronics are not as efficient as silicon ICs for computation and signal communication. Flexible hybrid electronics (FHE) leverages the strengths of these two dissimilar technologies. It uses flexible and printed electronics where flexibility and scalability are required, i.e., for sensing and actuating, and silicon ICs for computation and communication purposes. Combining flexible electronics and silicon ICs yields a very powerful and versatile technology with a vast range of applications. Here, the fundamental building blocks of an FHE system, printed sensors and circuits, thinned silicon ICs, printed antennas, printed energy harvesting and storage modules, and printed displays, are discussed. Emerging application areas of FHE in wearable health, structural health, industrial, environmental, and agricultural sensing are reviewed. Overall, the recent progress, fabrication, application, and challenges, and an outlook, related to FHE are presented.
396 citations
TL;DR: In this paper, a conformal wearable antenna that operates in the 2.36-2.4 GHz medical body-area network band is proposed, which is enabled by placing a highly truncated metasurface, consisting of only a two by two array of I-shaped elements, underneath a planar monopole.
Abstract: We propose a compact conformal wearable antenna that operates in the 2.36-2.4 GHz medical body-area network band. The antenna is enabled by placing a highly truncated metasurface, consisting of only a two by two array of I-shaped elements, underneath a planar monopole. In contrast to previously reported artificial magnetic conducting ground plane backed antenna designs, here the metasurface acts not only as a ground plane for isolation, but also as the main radiator. An antenna prototype was fabricated and tested, showing a strong agreement between simulation and measurement. Comparing to previously proposed wearable antennas, the demonstrated antenna has a compact form factor of 0.5 λ
0
×0.3 λ
0
×0.028 λ
0
, all while achieving a 5.5% impedance bandwidth, a gain of 6.2 dBi, and a front-to-back ratio higher than 23 dB. Further numerical and experimental investigations reveal that the performance of the antenna is extraordinarily robust to both structural deformation and human body loading, far superior to both planar monopoles and microstrip patch antennas. Additionally, the introduced metal backed metasurface enables a 95.3% reduction in the specific absorption rate, making such an antenna a prime candidate for incorporation into various wearable devices.
301 citations
Cites background or methods or result from "Flexible and Compact AMC Based Ante..."
...47 GHz, due to the decreased quality factor of the radiator caused by the lossy tissue model loading [1], [20]....
[...]
...In particular, a FB ratio of around 16–18 dB was achieved with an antenna footprint of around 1 [20], [21], [35], [36]....
[...]
...Most of the previously demonstrated integrated wearable antennas consisting of a radiator backed by an AMC ground plane have an operational band around the zero reflection phase frequency of the AMC ground plane [20], [21]....
[...]
...Hence, in contrast to previous designs where the metallic backed metasurface acts only as a high-impedance AMC reflector [19], [20], [35], [36], the finite-sized metasurface proposed in our design acts as the primary radiator....
[...]
...1 So far, several configurations have been investigated for their suitability as wearable antennas, including vertical monopoles [7], [8], [9], planar microstrip monopoles [10], [11], various inverted-F antennas [12]–[14], microstrip patch antennas [15], cavity-backed slot antennas [16], [17], reflector patch radiators [18], and artificial magnetic conducting (AMC) surface backed antennas [19], [20]....
[...]
TL;DR: In this article, a compact circularly polarized (CP) co-designed filtering antenna is reported, which is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system.
Abstract: A compact circularly polarized (CP) co-designed filtering antenna is reported. The device is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system. In the proposed design, the patch functions simultaneously as the radiator and the last stage resonator of the filter, resulting in a low-profile integrated radiating and filtering module with a small overall form factor of $\mathbf{0.53{\lambda _0} \times 0.53{\lambda _0} \times 0.07{\lambda _0}}$ . It is shown that the filtering circuit not only ensures frequency selectivity but also provides impedance matching functionality, which serves to broaden both the impedance and axial ratio bandwidths. The designed filtering antenna was fabricated and measured, experimentally achieving an $\mathbf{{S_{11}} , an axial ratio of less than 3 dB and a gain higher than 5.2 dBi over a bandwidth from 3.77 to 4.26 GHz, i.e., around 12.2%, which makes it an excellent candidate for integration into a variety of wireless systems. A linearly polarized version of the integrated filtering antenna was also demonstrated. In addition, further full-wave simulations and experiments were carried out to verify that the designed CP filtering antenna maintains its properties even when mounted on different positions of the human body with various body gestures. The stable impedance and radiation properties also make it a suitable candidate as a wearable antenna for off-body wireless communications.
188 citations
TL;DR: In this paper, the authors reviewed the evolution of wearable textile antennas over the last couple of decades and gave particular emphasis to the process of embroidery, which is advantageous for the following reasons: (i) bespoke or mass produced designs can be manufactured using digitized embroideries machines; (ii) glue is not required and (iii) the designs are aesthetic and are integrated into clothing rather than being attached to it.
Abstract: This paper will review the evolution of wearable textile antennas over the last couple of decades. Particular emphasis will be given to the process of embroidery. This technique is advantageous for the following reasons: (i) bespoke or mass produced designs can be manufactured using digitized embroidery machines; (ii) glue is not required and (iii) the designs are aesthetic and are integrated into clothing rather than being attached to it. The embroidery technique will be compared to alternative manufacturing processes. The challenges facing the industrial and public acceptance of this technology will be assessed. Hence, the key opportunities will be highlighted.
183 citations
Cites background from "Flexible and Compact AMC Based Ante..."
...The antenna on-body or on-phantom should be measured in terms of S11, near-field, far-field [110–112]....
[...]
TL;DR: In this article, a low-profile wearable antenna is presented for on-body wireless body area network (WBAN) applications, which combines the Koch fractal geometry, meandering slits, and defected ground structure to achieve a novel hybrid structure with compact footprint, good structural conformability, and enhanced impedance bandwidth.
Abstract: A compact and low-profile wearable antenna is presented for on-body wireless body area network (WBAN) applications. The proposed triangular patch antenna is designed using low-cost widely available vinyl polymer-based flexible substrate. The final antenna topology is obtained by the combination of the Koch fractal geometry, meandering slits, and defected ground structure, to achieve a novel hybrid structure with compact footprint, good structural conformability, and enhanced impedance bandwidth (BW) to operate in the Industrial, Scientific, and Medical band with center frequency at 2.45 GHz. The fabricated prototype of the antenna has shown a good agreement between numerical and experimental results. In comparison to state-of-the-art prototypes, our design has more compact form factor of 0.318λo × 0.318λo × 0.004λo, along with 7.75% impedance BW, a peak gain of 2.06 dBi, and overall radiated efficiency of 75%. For the assessment of a specific absorption rate (SAR) performance of our design, it is tested on realistic heterogeneous HUGO voxel model. Both numerical and experimental investigations revealed extremely good robustness to both human body loading and structural deformation, making it an ideal candidate for flexible and body-worn devices.
179 citations
Cites background from "Flexible and Compact AMC Based Ante..."
...Several such polymer-based materials are reported in literature including polytetrafluoroethylene (PTFE) [14], [15], Kapton polyimide [16], [17], poly 3,4-ethylenedioxthiophene [18], and polydimethylsiloxane substrate [19]....
[...]
References
More filters
TL;DR: In this paper, a new type of metallic structure has been developed that is characterized by having high surface impedance, which is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements and distributed in a two-dimensional lattice.
Abstract: A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.
4,264 citations
"Flexible and Compact AMC Based Ante..." refers background in this paper
...Hence, a significant amount of the electromagnetic energy is trapped between the antenna and the ground plane which in turn leads to a significant reduction in the antenna’s efficiency [13]....
[...]
TL;DR: In this article, a dual-band coplanar patch antenna integrated with an electromagnetic band gap substrate is described, where the antenna structure is made from common clothing fabrics and operates at the 2.45 and 5 GHz bands.
Abstract: Performance of a dual-band coplanar patch antenna integrated with an electromagnetic band gap substrate is described. The antenna structure is made from common clothing fabrics and operates at the 2.45 and 5 GHz wireless bands. The design of the coplanar antenna, band gap substrate, and their integration is presented. The band gap array consists of just 3 times 3 elements but reduces radiation into the body by over 10 dB and improves the antenna gain by 3 dB. The performance of the antenna under bending conditions and when placed on the human body are presented.
599 citations
"Flexible and Compact AMC Based Ante..." refers background in this paper
...Several techniques [5]–[8] have been reported to solve the aforementioned issues including the use of cavities, absorbers and shielding planes....
[...]
...In [8], the performance of a dual band (2....
[...]
TL;DR: In this paper, four purely textile patch antennas for Bluetooth applications in wearable computing using the frequency range around 2.4 GHz were presented, which can withstand clothing bends down to a radius of 37.5 mm without violating the Bluetooth specifications.
Abstract: In this paper, we present four purely textile patch antennas for Bluetooth applications in wearable computing using the frequency range around 2.4 GHz. The textile materials and the planar antenna shape provide a smooth integration into clothing while preserving the typical properties of textiles. The four antennas differ in the deployed materials and in the antenna polarization, but all of them feature a microstrip line as antenna feed. We have developed a manufacturing process that guarantees unaffected electrical behavior of the individual materials when composed to an antenna. Thus, the conductive textiles possess a sheet resistance of less than 1Omega/squarein order to keep losses at a minimum. The process also satisfies our requirements in terms of accuracy meeting the Bluetooth specifications. Our investigations not only characterize the performance of the antennas in planar shape, but also under defined bending conditions that resemble those of a worn garment. We show that the antennas can withstand clothing bends down to a radius of 37.5 mm without violating specifications
446 citations
"Flexible and Compact AMC Based Ante..." refers background in this paper
...The reader is referred to [21], [22] for detailed investigation on the effect of bending on the radiation pattern of flexible and wearable antennas....
[...]
TL;DR: The design, manufacture, and performance of the first textile planar antenna to be implemented on flexible protective foam, suitable for firefighter garments are described, which results in an antenna that is highly appropriate for garment integration.
Abstract: The introduction of intelligent textile systems to increase the wearer's level of protection has exposed the necessity of wearable communication tools and has led to research in textile antennas. However, most textile fabrics are quite thin (0.5 mm), making it challenging for antenna designers to provide an antenna which operates adequately and resiliently in the 2.4-2.4835-GHz industrial-scientific-medical bandwidth. Flexible pad foam is commonly available in protective clothing and overcomes these constraints by providing a uniform, stable, and sufficient thickness. Moreover, its cellular structure and properties, such as flame retardance and water repellence, make it an excellent substrate material for the integration of antennas into protective garments. In this paper, we describe the design, manufacture, and performance of the first textile planar antenna to be implemented on flexible protective foam, suitable for firefighter garments. We employed shock absorbing foam with a thickness of 3.94 mm and achieved a nearly circularly polarized antenna with a bandwidth of more than 180 MHz even when the antenna was compressed or bent. These outstanding substrate and antenna characteristics result in an antenna that is highly appropriate for garment integration.
412 citations
"Flexible and Compact AMC Based Ante..." refers background in this paper
...The reader is referred to [21], [22] for detailed investigation on the effect of bending on the radiation pattern of flexible and wearable antennas....
[...]
TL;DR: In this paper, the performance of a compact higher mode microstrip patch antenna (HMMPA) with a profile as low as lambda/20 was investigated by measuring |S 21| path gain between two devices mounted on tissue-equivalent numerical and experimental phantoms, representative of human muscle tissue at 2.45 GHz.
Abstract: In this paper, the on-body performance of a range of wearable antennas was investigated by measuring |S 21| path gain between two devices mounted on tissue-equivalent numerical and experimental phantoms, representative of human muscle tissue at 2.45 GHz. In particular, the study focused on the performance of a compact higher mode microstrip patch antenna (HMMPA) with a profile as low as lambda/20. The 5- and 10-mm-high HMMPA prototypes had an impedance bandwidth of 6.7% and 8.6%, respectively, sufficient for the operating requirements of the 2.45-GHz industrial, scientific, and medical (ISM) band and both antennas offered 11-dB higher path gain compared to a fundamental-mode microstrip patch antenna. It was also demonstrated that a 7-dB improvement in path gain can be obtained for a fundamental-mode patch through the addition of a shortening wall. Notably, on-body HMMPA performance was comparable to a quarter wave monopole antenna on the same size of groundplane, mounted normal to the tissue surface, indicating that the low-profile and physically more robust antenna is a promising solution for bodyworn antenna applications.
318 citations
"Flexible and Compact AMC Based Ante..." refers background in this paper
...The health parameters that may be forwarded to remote stations via wireless transmission (off body mode) range from basal body temperature, heart rate, respiratory rate, blood pressure, to glucose levels and Electro Cardio Gram (ECG) waveforms [2]....
[...]