Cheolbok Kim

A Compact Omnidirectional Self-Packaged Patch Antenna With Complementary Split-Ring Resonator Loading for Wireless Endoscope Applications

A patch loaded with a complementary split-ring resonator (CSRR) is fabricated on a flexible substrate and folded in a cylindrical shape, forming a self-packaged folded patch antenna with a quasi-omnidirectional radiation pattern. The space inside the cylindrical cavity is electromagnetically shielded by the ground plane of the patch, and therefore electronic circuits can be accommodated in it with little electromagnetic interference (EMI) from the antenna or other external electronics. The CSRR contributes to size reduction. As a test vehicle, a 2.4-GHz ISM-band folded patch antenna is designed, fabricated, and characterized for a wireless capsule endoscope application, where the implemented antenna has a patch length of 10.5 mm (0.11λ ) and a folded cylinder diameter of 10 mm. A 74% size reduction is achieved after CSRR loading. The antenna located at the outermost surface not only functions as an electromagnetic radiator and an EMI shield, but also serve as a mechanical packaging structure.

High frequency characterization and analytical modeling of through glass via (TGV) for 3D thin-film interposer and MEMS packaging

Through glass via (TGV) buried in a Corning glass substrate is characterized and modeled at high frequency range for applications of 3D thin-film interposer and MEMS packaging. A micromachined microstrip ring resonator is used for substrate characterization and a TGV test structure fed by a coplanar waveguide (CPW) is designed and analyzed in the microwave range. The lumped element parameters (RLGC) of the TGV are extracted using 3D electromagnetic (EM) simulations and an equivalent π-circuit model. The TGV with a diameter of 90 μm and a height of 500 μm, which is buried in a glass substrate with a relative dielectric constant of 7.9 and a loss tangent of 0.008, has a resistance of 2.2 Ω, an inductance of 0.3 nH, a conductance of 0.01 S and a capacitance of 1.8 pF at 1 GHz. Also, an effect of the diameter and height of TGV is investigated.

Room temperature multiferroic properties of (Fex, Sr1−x)TiO3 thin films

This letter reports the structural, dielectric, ferroelectric, and magnetic properties of Fe substituted SrTiO3 thin films in room temperature. The structural data obtained from x-ray diffraction indicates that (Fex,Sr1−x)TiO3, the so called FST, transforms from pseudocubic to tetragonal structures with increase of the Fe content in SrTiO3 thin films, featuring the ferroelectricity, while vibrating sample magnetometer measurements show magnetic hysteresis loops for the samples with low iron contents indicating their ferromagnetism. The characterized ferroelectricity and ferromagnetism confirms strong multiferroitism of the single phase FST thin films in room temperature. Also, an FST thin film metal-insulator-metal multiferroic capacitor has been fabricated and characterized in microwave frequencies between 10 MHz and 5 GHz. A capacitor based on Fe0.1Sr0.9TiO3 with a thickness of 260 nm shows a high electric tunability of 18.6% at 10 V and a maximum magnetodielectric value of 1.37% at 0.4 mT with a loss t...

Wireless passive sensing application using a cavity loaded evanescent mode half mode substrate integrated waveguide resonator

In this work, an evanescent mode half mode substrate integrated waveguide (HMSIW) resonator is designed for a wireless passive sensing application at 5 GHz. The wireless pressure sensor has been implemented by placing a small Polydimethylsiloxane (PDMS) cavity, covered with a metal coated membrane, on top of the original resonator or by using a cavity ground plane. When the metal coated membrane is deformed or deflected by an external pressure, it perturbs the electric field of a complementary split ring resonator (CSRR) patterned on top of the HMSIW, producing a shift in the resonance frequency. Because it operates in a microwave frequency spectrum, it offers a high pressure-frequency sensitivity. Resonance frequency as a function of an applied pressure has been presented. Also, a broadband antenna has been integrated to perform wireless interrogation of the sensor.

A compact self-packaged patch antenna with non-planar complimentary split ring resonator loading

A self-packaged folded patch antenna in a rectangular waveguide shape is greatly reduced in size by loading a complimentary split ring resonator (CSRR) on the edge of its ground plane. The dimensions of the proposed antenna are 15mm×15mm×20mm, showing 72% volume reduction compared to one without CSRR loading at the same radiation frequency of 2.4GHz. Impedance matching between the patch and the feeding line is obtained by adjusting the gap between two edges of the folded patch not necessitating an additional impedance matching circuit. Also, the inside cavity surrounded and packaged by the folded patch is electromagnetically well shielded from the external circuit. This antenna offers a quasi-omni-directional radiation pattern. All those features make the proposed antenna very suitable for a compact sensor network application. To our knowledge, this is the first report a non-planar CSRR applied to antenna size reduction.

A high gain circular polarization antenna using metamaterial slabs

Modern satellite communication systems often demand low-profile, wide bandwidth, high gain, and circular polarization antennas. Traditionally, a reflector antenna, a horn antenna, and a microstrip array antenna are widely used to achieve high gain circular polarization. Recently, a metamaterial approach has been emerged as a promising method for a high gain antenna. N. Guerin et al. [1] designed an antenna having a directivity of approximately 600 using the electromagnetic resonances of a Fabry-Perot cavity and S. Enoch et al. [2] introduced a metamaterial consisting of copper grids with square lattices for directive emission. C. Y. Wu et al. [3] improved antenna gain using radome having an inverted S-shaped metallic ring array. While increasing gain is relatively straight forward, it is not to achieve circular polarization. In fact, many conventional approaches for circular polarization are available [4], implementing a high gain circular polarization antenna using metamaterial remains as a big challenge.

Through Glass Via (TGV) disc loaded monopole antennas for millimeter-wave wireless interposer communication

A monopole antenna loaded with a circular disc is integrated on a glass interposer layer for millimeter-wave wireless communication applications. A Through Glass Via (TGV) is used as a main radiator and the circular disc is for a impedance matching. An omnidirectional radiation pattern formed by the monopole antenna allows in-plane wireless communication whose distance is much larger than 1cm. This can solve problems such as cross talk and time delay caused by the conventional wire bonding approach. A 77 GHz (W-band) antenna is designed and fabricated as a prototype on a glass substrate. The simulated peak gain of the antenna is 1.23 dBi. Also, as this antenna concept is scalable, the same architecture has been exercised for a 5.8 GHz industrial, scientific and medical, ISM band application. The design, fabrication, and characterization are detailed. The measured results of the return loss and radiation pattern agree well with the simulation results.

Fabrication of 3D nanostructures by multidirectional UV lithography and predictive structural modeling

This paper presents the fabrication and modeling of three-dimensional (3D) nanostructures by automated multidirectional ultraviolet (UV) lithography, which is a fast, cost-effective, manufacturable fabrication method. Multidirectional UV exposure is performed using a static UV light source equipped with a tilt-rotational substrate holder. A glass substrate with a nanopatterned chrome layer is utilized as both a photomask and a substrate, for which a backside UV exposure scheme is used. For the analytical modeling of the shape of fabricated nanostructures, UV exposure dosage, diffraction and refraction effects, and absorption rate are taken into account. For more accurate process predictive models, a commercially available multiphysics simulation tool is used. The structural shapes predicted from analytical calculation and simulation are compared with the fabricated ones for which various 3D nanoscale test structures are fabricated such as an inclined nanopillar array and a vertical triangular slab. Also, nanostructures with multiple heights are successfully implemented from single layer photoresist by controlling the UV exposure dosage and tilt angles. A tripod embedded horn and a triangular-slab embedded horn are demonstrated.

Through-glass interposer integrated high quality RF components

High quality and compact RF devices, using the half mode substrate integrated waveguide (HMSIW) architecture loaded with a complementary split ring resonator (CSRR), are implemented on a glass interposer layer, which therefore serves as an interconnection layer and as a host medium for integrated passive RF components. Compared with the silicon interposer approach, which suffers from large electrical conductivity and therefore substrate loss, the glass interposer has advantages of low substrate loss, allowing high quality interconnection and passive circuits, and low material and manufacturing costs. Corning fusion glass is selected as the substrate to realize the compact CSRR-loaded HMSIW resonators and bandpass filters (BPFs) working under the principle of evanescent wave amplification. Two and three pole bandpass filters are designed for broadband operation at 5.8 GHz. Thru glass vias (TGVs) are used to define the side-wall of the substrate integrated waveguiding structure. Surface micromachining techniques are used to fabricate the proposed devices. The variations of the external quality factor (Qe) of the resonator and the internal coupling coefficient (M) of the coupled resonators are studied for filter design. Operation of the filters at 5.8 GHz with a fractional bandwidth (FBW) of more than 10% for an in-band return loss of better than 20 dB and an low insertion loss of less than 1.35 dB has been obtained, which is not feasible with a usual Si interposer approach. Measurement results are presented from 2 to 10 GHz and show good agreement with simulated ones.

Micromachined wearable/foldable super wideband (SWA) monopole antenna based on a flexible liquid crystal polymer (LCP) substrate toward imaging/sensing/health monitoring systems

In this paper, a wearable/foldable super wideband (SWB) monopole antenna on a flexible liquid crystal polymer (LCP) substrate is implemented using surface micromachining for imaging, sensing, radar and healthcare monitoring systems. The antenna consists of a coplanar waveguide (CPW)-fed circular patch as a main radiator, a tapered transition portion between the patch and the CPW line, and corner-rounded ground planes, for broad bandwidth. The overall size of the antenna is 37.5 × 35.5 × 0.05 mm3. The fabricated SWB antenna is characterized in a frequency spectrum from 1 to 50 GHz. A measured ratio bandwidth of 11.9:1 (3.0 to 35.3 GHz or 169% bandwidth) has been obtained. The antenna has a monopole-like radiation pattern and a group delay of less than ±1 ns across all spectrum ranges. The measured results show good agreement with those of simulation.