Wireless Body Area Networking: Joint Physical-Networking Layer Simulation and Modeling

An electronic device equipped with sensors and antennas is the main part of the wireless body area networking (WBAN). Such a device is placed near human body and it usually works in a populated environment with many surrounding objects (e.g., building walls). The human body and the objects can change the radiation characteristics of the antenna and impact the performance of the wireless communication system. The wireless communication system’s performance is also affected by the networking layers established on top of the physical layer. Therefore, any designing method for WBAN application should be pervasive, offering a joint physical-networking layer simulation and modeling strategy. To this end, in this chapter, a comprehensive simulation and modeling method is presented. First, antenna design limitations and challenges for wireless body area networking are studied with emphasis on evaluating the antenna’s performance near the human body. Then, the antenna miniaturization techniques to reduce the antennas’ dimension are reviewed. Later, a system level analysis and modeling are used to study short-range communication between the wearable antennas with remote nodes using IEEE 802.11g wireless networking protocol

Synthetic aperture radar-based techniques and reconfigurable antenna design for microwave imaging of layered structures

In the past several decades, a number of microwave imaging techniques have been developed for detecting embedded objects (targets) in a homogeneous media. New applications such as nondestructive testing of layered composite structures, through-wall and medical imaging require more advanced imaging systems and image reconstruction algorithms (post-processing) suitable for imaging inhomogeneous (i.e., layered) media. Currently-available imaging algorithms are not always robust, easy to implement, and fast. Synthetic aperture radar (SAR) techniques are some of the more prominent approaches for image reconstruction when considering low loss and homogeneous media. To address limitations of SAR imaging, when interested in imaging an embedded object in an inhomogeneous media with loss, two different methods are introduced, namely; modified piecewise SAR (MPW-SAR) and Wiener filter-based layered SAR (WL-SAR). From imaging system hardware point-of-view, microwave imaging systems require suitable antennas for signal transmission and data collection. A reconfigurable antenna which its characteristics can be dynamically changed provide significant flexibility in terms of beam-forming, reduction in unwanted noise and multiplicity of use including for imaging applications. However, despite these potentially advantageous characteristics, the field of reconfigurable antenna design is fairly new and there is not a methodical design procedure. This issue is addressed by introducing an organized design method for a reconfigurable antenna capable of operating in several distinct frequency bands. The design constraints (e.g., size and gain) can also be included. Based on this method, a novel reconfigurable coplanar waveguide-fed slot antenna is designed to cover several different frequency bands while keeping the antenna size as small as possible --Abstract, page iii

Fast 3-D Qualitative Method for Through-Wall Imaging and Structural Health Monitoring

A fast non-iterative 3-D imaging method is developed which incorporates several critical approximations to overcome computational burden and data collection constraints associated with imaging layered media. The method first invokes dyadic Green\u27s function to relate the object reflectivity function (or image) to the collected data. Then, calculating the reflectivity function requires solving a computationally-intensive and ill-posed inverse problem. The data collection constraints and layered media modeling uncertainties also add to the complexity associated with this inverse problem. To address these challenges, a set of approximations are considered which simplify the imaging problem and cast it into a de-convolution problem with much less computational burden which is implemented using fast Fourier transform. The performance of the method is verified for through-wall imaging and structural health monitoring, indicating that it is reasonably tolerant to constraint associated with data collection limitations and modeling inaccuracies

Sensitivity Analysis of Wiener Filter-Based Synthetic Aperture Radar (SAR) Microwave Imaging Technique

Previously, a Wiener filter-based synthetic aperture radar (SAR) technique was developed to successfully image embedded objects in a general layered structure. The results of the imaging technique were then verified through performing extensive measurements. Here, the sensitivity of this technique to different critical parameters is investigated using a full-wave electromagnetic simulation software. These parameters include those related to the sample being imaged (e.g., electrical properties of layers), those related to measurements (e.g., electromagnetic wave polarization), and those associated with the modeling process (e.g., electrical properties of layers used in the image reconstruction procedure)

Antenna Miniaturization Techniques: A Review of Topology- and Material-Based Methods

Antenna miniaturization has been the subject of numerous studies for almost 70 years. Early studies showed that a decrease in the size of an antenna results in a direct reduction in its bandwidth and efficiency ηr. The size limitation translates into a lower boundary on the achievable radiation quality factor (Q factor) and consequently on the maximum achievable impedance bandwidth. Recently, many new investigations have been conducted to reduce the form factor (or the overall size) of different types of antennas while trying to maintain acceptable matching properties and operating bandwidth. These miniaturization techniques are generally related to changing the electrical and physical properties of an antenna

A Multiband Reconfigurable CPW-Fed Slot Antenna

A coplanar waveguide (CPW)-fed slot antenna loaded with electronically-controlled sub-wavelength slots is introduced. This reconfigurable antenna operates at several distinct bands with appreciable bandwidth and reasonable gain. Since the antenna is tuned electronically to operate at one band at a time, it does not suffer from noise and interference issue as much as multiband and wideband antennas

Miniaturized Reconfigurable Multiband Antenna for Multiradio Wireless Communication

This paper introduces a general methodical approach for designing frequency reconfigurable antennas. This method was successfully used to design a novel coplanar waveguide (CPW)-fed slot frequency reconfigurable antenna capable of operating at four preselected frequency bands distributed over a wide frequency range from ∼59.5 MHz to ∼1000 MHz (i.e., ∼4 octaves of bandwidth) while keeping its overall size as small as possible. To add reconfigurablility to the antenna, optimally-designed and electronically-controllable PIN diode-loaded slots were used to strategically manipulate the flow of current path and consequently change the characteristics of the antenna. Designing for the lowest operating frequency (59.5MHz), capacitor-loaded meandered slot lines and reconfigurable matching network were implemented to keep the size of the antenna as small as possible. The resulting overall size of the antenna is only 0.06λL × 0.06λL where λL is calculated at 59.5 MHz. The measurement results verified that the antenna successfully operates at 59.25-59.75 MHz, 314-398 MHz, 430-496 MHz, and 792-950 MHz, all with an almost omnidirectional pattern and an acceptable gain