Atif Shamim

Inkjet Printing of Novel Wideband and High Gain Antennas on Low-Cost Paper Substrate

A complete characterization of the inkjet printing process using metallic nanoparticle inks on a paper substrate for microwave frequencies up to 12.5 GHz as well as its application to low-cost, high gain and wideband antenna design are demonstrated in this work. Laser and heat sintering of metallic nanoparticles are compared on paper substrate for the first time which demonstrate immense cost and time benefits of laser sintering. The antennas fabricated using the characterized process include a Vivaldi for the UWB band which exhibits a significantly higher gain of up to 8 dBi as compared to the currently published inkjet printed antennas, and a novel slow-wave log periodic dipole array which employs a new miniaturization technique to show 20% width reduction.

The last barrier: on-chip antennas

This paper has presented a comprehensive overview of on-chip antennas, which remain the last bottleneck for achieving true SoC RF solutions. CMOS remains the mainstream IC technology choice but is not well suited for on-chip antennas, requiring the use of innovative design techniques to overcome its shortcomings. Codesign of circuits and antennas provide leverage to the designer to achieve optimum performance. The layout of on-chip antennas is dictated by foundry specific rules whereas characterization of on-chip antennas requires special text fixtures. For future highly integrated SoC solutions, foundries will have to provide special layers for efficient on-chip antenna implementations, as they currently do for on-chip inductors. In many of the emerging applications such as THz communication, implantable systems and energy harvesting, on-chip antennas have shown immense potential and are likely to play a major role in shaping up future communication systems.

Theory of Fractional Order Elements Based Impedance Matching Networks

Fractional order circuit elements (inductors and capacitors) based impedance matching networks are introduced for the first time. In comparison to the conventional integer based L-type matching networks, fractional matching networks are much simpler and versatile. Any complex load can be matched utilizing a single series fractional element, which generally requires two elements for matching in the conventional approach. It is shown that all the Smith chart circles (resistance and reactance) are actually pairs of completely identical circles. They appear to be single for the conventional integer order case, where the identical circles completely overlap each other. The concept is supported by design equations and impedance matching examples.

Design, Optimization and Fabrication of a 28.3 THz Nano-Rectenna for Infrared Detection and Rectification

The increasing energy demands of the worlds population and the quickly diminishing fossil fuel reserves together suggest the urgent need to secure long-lasting alternative and renewable energy resources. Here, we present a THz antenna integrated with a rectifier (rectenna) for harvesting infrared energy. We demonstrate a resonant bowtie antenna that has been optimized to produce highly enhanced localized fields at the bow tip. To benefit from this enhancement, the rectifier is realized between the overlapped antennas arms using a 0.7 nm copper oxide. The thin film diode offers low zero bias resistance of 500 Ω, thus improving the impedance matching with the antenna. In addition, the rectenna prototype demonstrates high zero bias responsivity (4 A/W), which is critical in producing DC current directly from THz signals without the application of an external electric source, particularly for energy harvesting applications.

24 GHz On-Chip Antennas and Balun on Bulk Si for Air Transmission

The conditions are investigated under which standard digital bulk Si technology can yield efficient on-chip antennas and baluns for fully differential transmitter and receiver implementations. The effects of the IC material properties and the antenna geometry on radiation and impedance characteristics have been studied. 24 GHz on-chip antennas on lossy Si have been successfully demonstrated, using a standard IC fabrication compatible Cu process. The fabricated antennas demonstrate a gain ranging from 8- to - 10.5 dBi, which is to the best of the authors knowledge, the highest gain reported for antennas in a 10 Omega-cm Si substrate to date.

Utilizing Wideband AMC Structures for High-Gain Inkjet-Printed Antennas on Lossy Paper Substrate

Significant gain and bandwidth improvement of inkjet-printed antennas with integrated artificial magnetic conductor (AMC) is achieved by utilizing wideband ground-backed frequency selective surfaces (FSSs) to overcome the high losses of organic substrates such as paper. A microstrip-fed monopole mounted on an artificial magnetic conductor is demonstrated to improve the gain by 5 dB over previous works and exhibit much wider impedance bandwidth while maintaining a thin antenna profile and a 20% electrical size reduction. The effect of AMC bandwidth on substrate losses and the gain reduction caused by finite AMC array effects are investigated in an effort to produce high-gain, miniaturized, low-cost wearable and structure mount antennas.

Fractional Smith Chart Theory

For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach.

Wireless Dosimeter: System-on-Chip Versus System-in-Package for Biomedical and Space Applications

A new floating-gate (FG) MOSFET based wireless dosimeter system-in-package (SiP) is presented. This miniature and completely integrated wireless dosimeter SiP comprises a CMOS FG radiation sensor and transmitter (TX) in a low-temperature co-fired ceramic (LTCC) package. The design is very well suited to wireless transmission of radiation sensor data in radiotherapy and to Extra Vehicular Activity Radiation Monitoring (EVARM) in space. Two different solutions, namely system-on-chip (SoC) and SiP, are demonstrated. In the SoC, which is size and power efficient, the TX includes an on-chip loop antenna which also acts as the inductor for the VCO resonant tank circuit. The SiP solution has an LTCC antenna with optimized impedance to conjugate match the TX chip. The radiation sensor demonstrates a measured sensitivity of 5 mV/rad. The SoC module size is only 2 mm2, consumes 5.3 mW of power and delivers -0.9 dBm of radiated power, sufficient to communicate with a low noise receiver connected to an off-chip patch antenna placed 1.38 m away. The SiP design provides a larger communication range of 75 m at the cost of additional power consumption and size.

Fully Inkjet Printed RF Inductors and Capacitors Using Polymer Dielectric and Silver Conductive Ink With Through Vias

In this paper, fully inkjet printed multilayer capacitors and inductors are fabricated and characterized using poly 4-vinylphenol (PVP) ink as the dielectric layer and silver nanoparticle ink as the conductor. Inkjet printed through vias, created with a novel dissolving method are used to make RF structures in a multilayer inkjet printing process. The vias have been realized in a 350-nm PVP film and exhibit resistance better than 0.1 Ω. Spiral inductors from 10 to 75 nH have been realized with maximum quality factors around five. The 10-nH inductor exhibits a self-resonant frequency slightly below 1 GHz. Metal-insulator-metal capacitors are realized with densities of 50 pF/mm2. These capacitors demonstrate values ranging from 16 to 50 pF. The 16-pF capacitor shows a self-resonant frequency over 1.5 GHz. The successful implementation of inductors and capacitors in an all inkjet printed multilayer process with vias is an important step toward fully inkjet-printed large area and flexible RF systems.

Theory and Design of a Tunable Antenna on a Partially Magnetized Ferrite LTCC Substrate

For the first time, a theoretical model is presented to predict the frequency tuning of a patch antenna on a partially magnetized ferrite substrate. Both extraordinary (E) and ordinary (O) modes of the antenna are studied. The permeability tensor of the partially magnetized ferrite is calculated through the proposed theoretical model and is subsequently used to analyze the antennas performance in a microwave simulator. Prototype antennas were built, using two different bias windings, embedded in a multilayer ferrite LTCC substrate, to demonstrate E and O mode tuning. The use of embedded windings negates the requirement of bulky electromagnets, thus providing miniaturization. The concept also eliminates the demagnetization effect, thus reducing the typically required bias fields by 95%. The prototype measurements at 13 GHz demonstrate an E-mode tuning range of 10%. The proposed theoretical model has been validated by simulations and measurements. The design is highly suitable for compact, light-weight, tunable and reconfigurable microwave systems.