WiPrint: 3D Printing Your Wireless Coverage

Wireless signals are everywhere in residential, commercial and industrial environments. Directing wireless signals to conform to custom physical boundaries is of great importance in improving the performance, security and privacy of a wireless system. Unfortunately current solutions like directional antennas are bulky and expensive for ordinary users. We propose WiPrint, a novel approach to customizing wireless signal maps using 3D printed glossy reflectors. This solution is easily manufactured and adapts easily to different environments. The WiPrint system is highly flexible as it does not require adding additional APs or moving the AP to new locations. This is significant in the field of wireless networking as it provides consumers with an intuitive and novel solution to performance and security problems

A D-band 3D printed antenna

This paper reports the design and fabrication of a novel all-metal antenna operating in the millimeter-wave band. Based on the resonant cavity antenna (RCA) concept, the principle of antenna operation is explained, and a parametric study of several key design parameters is provided. A novel impedance matching technique is introduced to broaden the antenna return loss bandwidth. Two gain enhancement methods have been employed to achieve a more directive beam with reduced side lobes and back lobes. The D-band antenna prototypes are produced using i) all-metal printing without any post-processing; ii) dielectric printing with copper metallization applied later. Comparisons of the simulated and measured results amongst the antennas fabricated using the two additive manufacturing techniques are made. Measurement results of the two antenna prototypes show that the proposed design can achieve a 14.2% bandwidth with a maximum gain of 15.5 dBi at 135 GHz. The present work is the first D-band resonant cavity antenna fabricated using two different 3D printing methods

Emerging technologies for the non-invasive characterization of physical-mechanical properties of tablets

The density, porosity, breaking force, viscoelastic properties, and the presence or absence of any structural defects or irregularities are important physical-mechanical quality attributes of popular solid dosage forms like tablets. The irregularities associated with these attributes may influence the drug product functionality. Thus, an accurate and efficient characterization of these properties is critical for successful development and manufacturing of a robust tablets. These properties are mainly analyzed and monitored with traditional pharmacopeial and non-pharmacopeial methods. Such methods are associated with several challenges such as lack of spatial resolution, efficiency, or sample-sparing attributes. Recent advances in technology, design, instrumentation, and software have led to the emergence of newer techniques for non-invasive characterization of physical-mechanical properties of tablets. These techniques include near infrared spectroscopy, Raman spectroscopy, X-ray microtomography, nuclear magnetic resonance (NMR) imaging, terahertz pulsed imaging, laser-induced breakdown spectroscopy, and various acoustic- and thermal-based techniques. Such state-of-the-art techniques are currently applied at various stages of development and manufacturing of tablets at industrial scale. Each technique has specific advantages or challenges with respect to operational efficiency and cost, compared to traditional analytical methods. Currently, most of these techniques are used as secondary analytical tools to support the traditional methods in characterizing or monitoring tablet quality attributes. Therefore, further development in the instrumentation and software, and studies on the applications are necessary for their adoption in routine analysis and monitoring of tablet physical-mechanical properties

Dual-band 4G eyewear antenna and SAR implications

This paper presents low-cost and easy-to-manufacture dual-band antenna solution to achieve cellular 4G (LTE-Advanced) coverage in smart eyewear devices. Coupling element type antenna has been evaluated with appropriate matching networks to cover the target bands of 700-960MHz and 1.7-2.7GHz. To emulate a realistic device, an ABS plastic dielectric frame has been designed and manufactured using 3D printing technology. Simulations for the antenna are carried out in three typical use-case scenarios which are "with user's head", "with head and hand" and "free space". The simulations are validated through S-parameters, efficiency and radiation pattern measurements using fabricated frame and antenna prototype in the presence of head and hand phantoms. The SAR behavior of the antenna designs is also investigated through simulations and measurements. It is demonstrated that SAR values are found to be above the limitations which might be problematic in practical use if the transmit power of the eyewear is not reduced

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

The Economics of “Wireless Net Neutrality”

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Customizing Indoor Wireless Coverage via 3D-Fabricated Reflectors

Judicious control of indoor wireless coverage is crucial in built environments. It enhances signal reception, reduces harmful interference, and raises the barrier for malicious attackers. Existing methods are either costly, vulnerable to attacks, or hard to configure. We present a low-cost, secure, and easy-to-configure approach that uses an easily-accessible, 3D-fabricated reflector to customize wireless coverage. With input on coarse-grained environment setting and preferred coverage (e.g., areas with signals to be strengthened or weakened), the system computes an optimized reflector shape tailored to the given environment. The user simply 3D prints the reflector and places it around a Wi-Fi access point to realize the target coverage. We conduct experiments to examine the efficacy and limits of optimized reflectors in different indoor settings. Results show that optimized reflectors coexist with a variety of Wi-Fi APs and correctly weaken or enhance signals in target areas by up to 10 or 6 dB, resulting to throughput changes by up to -63.3% or 55.1%