Vamsi Krishna Palukuru

CAPACITIVE RECOGNITION OF THE USER'S HAND GRIP POSITION IN MOBILE HANDSETS

A capacitive method for measuring hand grip position on a mobile phone equipped with a dual-band planar inverted-F antenna (PIFA) and a monopole antenna was studied using difierent electrode arrangements. A capacitive sensor with a dual-electrode conflguration and an antenna-integrated capacitive sensor for hand grip recognition were developed. The sensitivities of the sensors were measured along the front, side and back of the phone. The dual-electrode sensor conflguration exhibited its best sensitivity of 29fF at the bottom end of the phone. The PIFA antenna-integrated sensor proved to have sensitivity of 420fF and the monopole antenna-integrated sensor had sensitivity of 115fF, making them both reasonable solutions for hand grip sensors in mobile applications.

PERFORMANCE OF PRINTABLE ANTENNAS WITH DIFFERENT CONDUCTOR THICKNESS

This paper shows that L-shaped monopole antenna on PPS manufactured by inkjet printing of nano silver ink is able to produce very competitive overall antenna performance against Rogers copper foil structures if the thickness of the printed conductor layer is about the skin depth at the operating frequency multiplied by four.

Frequency-tunable DVB-H antenna for mobile terminals

In this paper a frequency-tunable inverted F-antenna (IFA) for DVB-H reception is presented. The antenna is suitable for small mobile devices (40 mm times 90 mm times 10 mm). The operating frequency of the antenna is tuned with a varactor component. The varactor loads the IFA element and thus enables it to resonate at different frequencies. This kind of tunable narrowband antenna is suitable for DVB-H reception, since one channel in a bandwidth of 8 MHz is received at a time. The antenna presented in this paper can be compared with a frequency- tunable IFA of Ying (2005), presented in a recently published patent. This proves the potential of this kind of DVB-H antenna solution in commercial applications. A special advantage of the proposed antenna is that, since it can be located in a vertical position on the long side of the ground plane, as opposed to the work of Ying (2005), GSM antennas can be located in their optimal position at the upper part of the device.

Formulation of Screen Printable Cobalt Nanoparticle Ink for High Frequency Applications

In this work, magnetic metallic cobalt nanoparticles with an average particle size of 28nm were processed as a dry powder with surface coating material and other organic additives to form a screen-printable ink to be cured at 110 - C. EFTEM and TGA-DSC- MS-analyses were used to measure the thickness of the polymer, its coverage on cobalt nanoparticles and the inorganic solid content of the ink. The resolution of the printed patterns and the print quality were evaluated by surface profller, FESEM and optical microscopy. The relative permeability of the thick fllm patterns with good printability was measured with a shorted microstrip structure over the frequency range of 0.2 to 4GHz and complex permeability values were calculated from measured scattering parameter data. The ink attained real part of complex permeability values of up to 5.13 at 200MHz with 70wt.% of magnetic flller. The developed ink can be utilized in various printed electronics applications such as antenna substrates and magnetic sensors.

Application of Wide-Band Material Characterization Methods to Printable Electronics

In this paper, characterization methods are presented with results from test structures printed with varying printing parameters and materials. It is shown that different process parameters affect both physical and electrical material properties and hence high-frequency material characterization is a vital part of the process providing important information for design purposes. The conductivities and loss information of nanoparticle inks and properties of dielectric material are achieved in addition to structural properties. In particular, dc measurement results from 1.1e7 S/m to 3.7e7 S/m and high-frequency attenuation values from 0.5 dB/cm to 2.8 dB/cm (at 10 GHz) are achieved for printed conductors.

Low-Sintering-Temperature Ferroelectric-Thick Films: RF Properties and an Application in a Frequency-Tunable Folded Slot Antenna

This investigation is one of the first steps toward the realization of low-cost, mass-producible, tunable antenna applications utilizing an integrated ferroelectric-thick film made of bariumstrontiumtitanate material. The dielectric properties of the electric-field-adjustable fired BST thick film are presented in the frequency range of 16 GHz. The key advantages of the material are high tunability (25% with 2.5 V/mum), compatibility with silver electrodes, and the ability to produce film thicknesses down to 25 mum. The utilization of the material is demonstrated by tuning the operating frequency of a folded slot antenna with an integrated variable capacitor. In addition, the impact of tuning on the antennas total efficiency and radiation pattern is experimentally studied through a comparison with the performance of a reference antenna not incorporating the varactor.

Application of wide-band material parameter extraction techniques to printable electronics characterization

Material characterization is an important part of printable electronics design, since material properties depend strongly on the manufacturing process. This paper reviews application of wide-band extraction techniques to printable electronics characterization. The extraction methods are validated using full-wave simulation data with exactly known reference for material parameters. Suitable test structures are evaluated and applied to printable electronics characterization.

BST-Coc Composite Based Rectangular Dielectric Resonator Antenna (DRA) for 2.4 WLAN Wrist Applications

A rectangular dielectric resonator antenna (DRA) based on Barium Strontium Titanate-Cyclic Olefln Copolymer (BST-COC) composite for 2.4GHz wrist application is designed and characterized. The dielectric properties of the composite with » 57 vol.% BST loading are characterized using microstrip ring resonator structures at 2.45GHz frequency. The proposed DRA, flxed onto a reverse grounded FR4 laminate, has a very compact size of 19mm£10mm£5mm. The impact of the users body proximity on the radiation performance of the antenna is studied experimentally. The percentage total e-ciency and gain of the antenna deteriorated by about 8.5% and 2dB due to the proximity of the users body. The proposed DRA showed better performance than that of resonant type of antennas when close to the users body.

Frequency-reconfigurable dual-band monopole antenna for mobile handsets

The main purpose of this paper is to present a method for electrically reconfiguring the operating frequency of a planar monopole antenna. In this method a tuning circuit composed of a RF PIN diode switch and two discrete passive components is built inside the antenna structure. This allows a DC control voltage to be brought to the diode switch along with the RF signal. Thus, this method of tuning does not require separate DC wiring, unlike commonly used structures proposed by Zachou et al. The method presented is demonstrated with a dual-band monopole antenna applicable in a mobile handset. The antenna has the capability of switching the lower band between the GSM850 and GSM900 frequency ranges with only a minor impact on the upper band. The upper band covers the frequency ranges of the GSM1800 and DCS 1900 telecommunication standards. Along with the antenna structure, the measured return loss and far-field gain are presented and discussed.

Wide-band Electrical Characterization of printable nano-particle copper conductors

Copper nano-particle ink suitable for printing is a promising substitute for silver- or gold-based inks for consumer electronics applications. However, oxidization must be controlled during the manufacturing and sintering processes. In this work conductors created from a copper nano-particle ink are characterized. In order to mitigate oxidation effects, the ink was formulated in inert atmosphere. Sintering is achieved by exposure to a short light pulse, which, due to the short time scales (ms) and added benefit of photoreduction, can be done in air. Wide-band electrical characterization results up to 20 GHz for copper nano-particle conductors are presented. Structural analysis using scanning-electron microscope (SEM) complements the characterization. Based on high-frequency measurements, wide-band material parameter extraction techniques, and modeling-based analysis of measurement results, the conductivity was found to be of the order of 0.7·107 S/m. All loss mechanisms including impurities deposited within the metal, porosity, surface roughness, and variation in structure geometry are attributed to the conductivity. The electrical performance was found almost comparable to that of silver-based inks. Also the average measured direct-current (dc) conductivity 1.37·107 S/m is similar to that of typical nano-metal conductors.