International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented.

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Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

One of the main problems in underwater communications is the low data rate available due to the use of low frequencies. Moreover, there are many problems inherent to the medium such as reflections, refraction, energy dispersion, etc., that greatly degrade communication between devices. In some cases, wireless sensors must be placed quite close to each other in order to take more accurate measurements from the water while having high communication bandwidth. In these cases, while most researchers focus their efforts on increasing the data rate for low frequencies, we propose the use of the 2.4 GHz ISM frequency band in these special cases. In this paper, we show our wireless sensor node deployment and its performance obtained from a real scenario and measures taken for different frequencies, modulations and data transfer rates. The performed tests show the maximum distance between sensors, the number of lost packets and the average round trip time. Based on our measurements, we provide some experimental models of underwater communication in fresh water using EM waves in the 2.4 GHz ISM frequency band. Finally, we compare our communication system proposal with the existing systems. Although our proposal provides short communication distances, it provides high data transfer rates. It can be used for precision monitoring in applications such as contaminated ecosystems or for device communicate at high depth.

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Underwater wireless sensor communications in the 2.4 GHz ISM frequency band.

A compact dual-band rectangular microstrip antenna (RMSA) is realized by two different single-slotted single-band rectangular microstrip antennas with slotted ground plane. Each open-ended slot in the single-slotted antenna is responsible to generate a wide impedance band that is shifted to lower frequencies by the effect of the ground slot. The length and position of each open-ended slot is varied to operate the antenna in a suitable resonant band (5.15-5.35 and 5.725-5.825 GHz). The proposed antenna meets the required impedance bandwidth, necessary for dual-band IEEE 802.11a WLAN application (5.125-5.395 and 5.725-5.985 GHz). The dimension of the antenna (12 × 8 × 1.5875 mm3) shows an average compactness of about 53.73% with respect to a conventional unslotted rectangular microstrip patch antenna.

Compact Dual-Band Microstrip Antenna for IEEE 802.11a WLAN Application

The field of flexible antennas is witnessing an exponential growth due to the demand for wearable devices, Internet of Things (IoT) framework, point of care devices, personalized medicine platform, 5G technology, wireless sensor networks, and communication devices with a smaller form factor to name a few. The choice of non-rigid antennas is application specific and depends on the type of substrate, materials used, processing techniques, antenna performance, and the surrounding environment. There are numerous design innovations, new materials and material properties, intriguing fabrication methods, and niche applications. This review article focuses on the need for flexible antennas, materials, and processes used for fabricating the antennas, various material properties influencing antenna performance, and specific biomedical applications accompanied by the design considerations. After a comprehensive treatment of the above-mentioned topics, the article will focus on inherent challenges and future prospects of flexible antennas. Finally, an insight into the application of flexible antenna on future wireless solutions is discussed.

Flexible Antennas: A Review.

In this communication, a compact two-element ultra-wideband (UWB) wearable multiple-input multiple-output (MIMO) antenna with high port isolation is presented. The proposed structure is composed of jeans material in which an `8' shaped stub is placed on the middle position of the antenna backside and connected to the partially suppressed ground structure to improve the port isolation characteristics. The antenna covers the frequency range from 2.74 to 12.33 GHz (about 127.27%) with the port isolation of >26 dB over the entire UWB frequency range. The envelope correlation co-efficient is found to be 9.9) throughout the complete operating band. The channel capacity loss for the proposed MIMO antenna is <;0.13 bit/s/Hz. The imprinted optimised UWB MIMO antenna covers the area size of 55 × 35 mm
 2
. The performances of the proposed antenna by the simulation and experimentation equally designated it a blameless candidate for the UWB applications.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-map.2018.5599

Compact wearable MIMO antenna with improved port isolation for ultra-wideband applications

- A single feed compact square microstrip antenna is proposed in this paper. Two L slits are introduced on the right edge of the patch to study the effect of the slit on radiation behavior with respect to a conventional microstrip patch. An extensive analysis of the return loss, radiation pattern and efficiency of the proposed antenna is shown in this paper. For the optimize value of the slit parameters antenna resonant frequencies are obtained at 2.16, 2.68,3.22&4.37 GHz with corresponding bandwidth 11.02 MHz, 13.07 MHz, 35.86 MHz , 48.56 MHz and return loss of about -23.4,-15.2,-30.6&-20.3 dB respectively. For the lowest esonant frequency (2.16 GHz) the size of the antenna has been reduced by 71.14 % when compared to aconventional rectangular microstrip patch. Thecharacteristics of the designed structure are nvestigated by using MoM based electromagnetic solver, IE3D. The simple configuration, low profile nature, reduced size and quad band characteristics of the proposed antenna makes it suitable to operate in the frequency ranges of 2.165-2.176, 2.673-2.686, 3.208-3.244 and 4.343-4.392 GHz.

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A Compact Microstrip Patch Antenna for Wireless Communication

A single feed compact rectangular microstrip antenna is presented in this paper. A triangular slot is introduced at the upper edge of the patch to reduce the resonant frequency. A small piece of triangular patch is added within the area of the triangular slot to improve the gain bandwidth performance of the antenna. The antenna size has been reduced by 46.2% when compared to a conventional square microstrip patch antenna with a maximum of 160MHz bandwidth and i27:36dB return loss. The characteristics of the designed structure are investigated by using MoM based electromagnetic solver, IE3D. An extensive analysis of the return loss, radiation pattern, gain and e-ciency of the proposed antenna is shown in this paper. The simple conflguration and low proflle nature of the proposed antenna leads to easy fabrication and make it suitable for the

/pdf/a-comact-microstrip-patch-antenna-for-wireless-communication-d4wrqqckry.pdf

A Comact Microstrip Patch Antenna for Wireless Communication

This article presents a unique meta-inspired decoupling method to reduce the isolation in a multi-band MIMO antenna. The proposed textile-based antenna is designed to cover the frequency spectra of IEEE 802.11a and b/g/n (2.4–2.484 GHz and 5.15–5.85 GHz) WLAN applications. The isolation improvement in multiple WLAN frequencies are achieved by a modified SRR meta-inspired structure without upsetting the parameters of the MIMO antenna. The maximum isolation improvement of around 10 dB is obtained at 2.4 GHz (S21   9 respectively over the desired bands. The measured results show a good agreement with the simulated one.

Ujjal Chakraborty

Papers

Compact Dual-Band Microstrip Antenna for IEEE 802.11a WLAN Application

Compact wearable MIMO antenna with improved port isolation for ultra-wideband applications

A Compact Microstrip Patch Antenna for Wireless Communication

A Comact Microstrip Patch Antenna for Wireless Communication

Mutual Coupling Reduction in a Multi-band MIMO Antenna Using Meta-Inspired Decoupling Network