Sami Myllymaki

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.

Compensation of finger effect on a mobile terminal antenna by antenna selection

In this paper, compensation of the effect of the users finger on the operation of a mobile terminal antenna is studied, using antenna selection as the compensation method. A dual-element antenna is compared with a single-element antenna occupying the same total antenna volume. The results show that antenna selection can provide an improvement of at least 2 dB in total efficiency at GSM1800 frequency band when the antenna is under influence of the index finger of the user.

Capacitive Sensor Arrangement to Detect External Load on a Mobile Terminal Antenna

The feasibility of using a capacitive sensor to sense the proximity of an external load, especially a finger, to a mobile terminal antenna was experimentally studied using a PIFA-type antenna as one of the sensor’s electrodes. It was found that with the proposed arrangement it is possible to detect objects with permittivity close to that of body tissue or the conductivity level of aluminium and the size of a human finger at distances up to 15 mm.

Capacitive Sensing of Antenna Loading With an R–C Voltage Divider in a Tunable Antenna

This paper presents a capacitive sensor for antenna applications. The sensor is based on measuring voltage in a voltage divider made of a resistor and a capacitor formed in an antenna structure. The purpose of the device is to detect when the user of a mobile device holds a finger near the antenna element and allow triggering of compensation measures to regain antenna performance. A planar monopole antenna with an impedance tuning element was constructed for this purpose, and measurements showed that 10% of lost total efficiency can be regained by applying retuning. The sensor can measure capacitance changes of 5 fF and detect a human finger at up to a distance of 1 cm. Some design issues and caveats are also discussed.

Failure mode characterization in inkjet-printed cpw lines utilizing a high-frequency network analyzer and post-processed tdr analysis

Failure mode characterization was applied to coplanar transmission lines by utilizing 0.5{10-GHz S-parameter measurements and post-calculated TDR (Time-Domain-Re∞ectometry) analysis. Coplanar waveguide transmission lines were inkjet-printed on 1.0-mm- thick ∞exible plastic RF substrates. Inductive, resistive, and capacitive types of failures | as the main failure modes caused by manufacturing, bending, or thermal cycling stresses | were investigated. The inkjet- printed CPW (Co-Planar Waveguide) lines were damaged by inductive shorts due to mechanical hitsor resistive and capacitive failures due to bending of the substrate. By using the TDR method the type and physical location of the failure can be determined.

Microwave Characterization of Printed Inductors with Ferrimagnetic BaFe12O19 Composite Layers

Microwave properties of a novel and functional composite inorganic materials based on barium hexaferrite (BaFe12O19) were measured and simulated. Three different inks with flake and sphere shape particles were developed and printed on the top of meander-shaped microwave inductor on alumina substrate. Several types of meandered inductors with a different number of turns were investigated for the verification of obtained results. The results show relative permeability values of 1.3, 2.2, and 1.5 for composite layers printed from the inks with flake shape at 41.5 wt.%, flake shape plus dodecyl benzene sulphonic acid (DBsa) at 44.4 wt.%, and sphere-like shape at 55.6 wt.% of BaFe12O19, respectively, at 3 GHz. Corresponding magnetic loss tangents were 0.015, 0.04, and 0.02. This novel inductor composite material can be applied for mobile telecommunication operations at 0.5 to 3 GHz frequency range.

Capability Assessment of Inkjet Printing for Reliable RFID Applications

In this paper, inkjet-printed silver traces and interconnections produced with the print-on-slope technique were used in an radio-frequency identification (RFID) structure operating in the ultra-high-frequency range. Underfill material was used to attach silicon RFID chips onto flexible, 125-

Towards Fully Printed, Antenna-Based Proximity Sensors

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FEASIBILITY STUDY OF ANTENNA INTEGRATED CAPACITIVE SENSOR IN OPERATIONAL MOBILE PHONE

-thick polymer substrates. The cured underfill was also used as a sloped surface for printing interconnection traces from the chip to the plastic substrate’s radiators. Inkjet printing was performed in one phase, producing both the interconnections to the chip and the radiators. This enables the use of a single-phase continuous roll-to-roll compatible process instead of the commonly used two-phase stop-and-go process. To further investigate the behavior of the printed low-temperature nanoparticle ink and its compatibility with different substrate materials, basic conductive traces were printed onto the substrates. Thereafter, the structures were exposed to thermal/humidity tests at 85 °C temperature/85% relative humidity (“85/85”) for up to a 2000-h period. To gain an understanding of the response of the structures under stress, the samples were intermittently characterized by using a read range measurement device, followed by the removal of failed samples from the test. The samples were characterized also by optical imaging and field-emission scanning electron microscopy. The bulk conductive traces were characterized electrically by measuring their resistances during test breaks. The results point out that although some challenges are still to overcome, inkjet printing is a feasible way of producing conductive traces for RFID structures, and that the print-on-slope technique is utilizable also in practical applications as a cost-effective method with adequate reliability for producing interconnections between chip and substrate.

Capacitive-Sensor-Induced Losses in 900-, 1800-, and 1900-MHz Antennas

In this work, we describe proximity sensors using functional coatings as sensing elements. The planar inductor-capacitor resonant circuit is fabricated by conventional PCB fabrication techniques an ...