Koch Fractal Shape Microstrip Bandpass Filters on High Resistivity Silicon for the Suppression of the 2<SUP>nd</SUP> Harmonic

Manos M. Tentzeris,Joy Laskar,Jong-Gwan Yook,Il Kwon Kim,Nickolas Kingsley,Matthew A. Morton,Stephane Pinel,John Papapolymerou 한국전자파학회JEES 2006 Journal of Electromagnetic Engineering and Science Vol.6 No.4

In this paper, the fractal shape is applied to microstrip band pass filters and integrated on a high-resistivity Si substrate to solve conventional 2<SUP>nd</SUP> harmonic problem. Conventional microstrip coupled line filters are popular in RF front ends, because they can be easily fabricated and integrated with other RF components. However, they typically have large second harmonics that can cause unwanted interference in interested frequency bands. Without any additional filters, the proposed Koch shape filters have suppressed the 2<SUP>nd</SUP> harmonics by about ?40㏈, so they can be used in systems such as direct conversion receiver with stringent harmonic suppression requirements.

Frequency-Tunable Electromagnetic Absorber by Mechanically Controlling Substrate Thickness

Jeong, Heijun,Tentzeris, Manos M.,Lim, Sungjoon Hindawi Limited 2018 International journal of antennas and propagation Vol.2018 No.-

<P>In this paper, we propose a frequency-tunable electromagnetic absorber that uses the mechanical control of substrate thickness. The absorption frequency of the proposed absorber can be changed by varying the substrate thickness. In order to mechanically control the substrate thickness, we introduce a 3D-printed molding with air space. The proposed structure consists of two layers and one frame: the FR4 substrate, polylactic acid (PLA) frame, and air substrate. The FR4 and PLA thicknesses are fixed, and the air thickness is varied using the PLA frame. Therefore, the effective dielectric constant of the overall substrate can be changed. The metallic rectangular patch and ground are patterned on the top and bottom FR4 substrates, respectively. The performance of the proposed tunable absorber is demonstrated from full-wave simulation and measurements. When both of the FR4 substrate thicknesses are 0.3 mm and the air thickness is changed from 1 to 3.5 mm, the absorption frequency is changed from 8.9 to 8.0 GHz, respectively. Therefore, the frequency-tuning capability of the proposed absorber is successfully demonstrated.</P>

Low-Cost Circularly Polarized Origami Antenna

Shah, Syed Imran Hussain,Tentzeris, Manos M.,Lim, Sungjoon IEEE 2017 IEEE antennas and wireless propagation letters Vol.16 No.-

<P>In this letter, we present a novel circularly polarized (CP) origami antenna. We fold paper in the form of an origami tetrahedron to serve as the substrate of the antenna. The antenna comprises two triangular monopole elements that are perpendicular to each other. Circular polarization characteristics are achieved by exciting both elements with equal magnitudes and with a phase difference of 90 degrees. In this letter, we explain the origami folding steps in detail. We also verify the proposed concept of the CP origami antenna by performing simulations and measurements using a fabricated prototype. The antenna exhibits a 10-dB impedance bandwidth of 70.2% (2.4-5 GHz), and a 3-dB axial-ratio bandwidth of 8% (3.415-3.7 GHz). The measured left-hand circular polarization gain of the antenna is in the range of 5.2-5.7 dBi for the 3-dB axial-ratio bandwidth.</P>

Inkjet-printed flexible ultrasensitive chemiresistive sensors for aggregation pheromone of flour beetles

Yunnan Fang,Manos M. Tentzeris 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.3

This work reports the fi rst demonstration that a chemoresistive sensor can be used to detect the aggregation pheromone offl our beetles. To prepare the sensing element of such a sensor, a novel functionalization method was developed to amplifyamine groups on the surface of carbon nanotubes (CNTs). Unlike traditional amine-amplifi cation approaches in which amplification effi ciency is signifi cantly reduced by self-crosslinking, the current amine amplifi cation process was self-crosslinkingfreedue to the use of a home-made compound in which amine groups were protected by Boc (tert-butyloxycarbonyl) protectinggroups and could be deprotected as needed. The inkjet ink formulated from the functionalized CNTs, together with anamine-rich compound and a commercial silver nanoparticle-based inkjet ink, was used to fabricate (via inkjet-printing anddrop-casting) lightweight, fl exible, and miniature-sized chemiresistive sensors for 4,8-dimethyldecanal (DMD), a compoundknown to be the aggregation pheromone of several species of fl our beetles. A home-built gas sensing system, including acommercial gas generator, a DMD permeation tube with its emission rate certifi ed, a data-acquisition system, and somehome-developed LabVIEW-based programs, was utilized to perform the DMD sensing trials. The sensors showed ultra-highsensitivity to synthetic aggregation pheromone DMD, as indicated by their prompt and signifi cant responses to 100 ppbDMD vapor. A mechanism for the sensitive sensing of DMD is proposed.

A Novel Fluid-Reconfigurable Advanced and Delayed Phase Line Using Inkjet-Printed Microfluidic Composite Right/Left-Handed Transmission Line

Sungjin Choi,Wenjing Su,Tentzeris, Manos M.,Sungjoon Lim IEEE 2015 IEEE microwave and wireless components letters Vol.25 No.2

<P>In this letter, a novel fluid-reconfigurable advanced and delayed phase line using a microfluidic composite right/left-handed (CRLH) transmission line (TL) is proposed. A CRLH-TL prototype is inkjet-printed on a photo-paper substrate. In addition, a laser-etched microfluidic channel in poly(methyl methacrylate) (PMMA) is integrated with the CRLH TL using inkjet-printed SU-8 as a bonding material. The proposed TL provides excellent phase-tuning capability that is dependent on the fluidic materials used. As the fluid is changed, the proposed TL can have negative-, zero-, and positive-phase characteristics at 900 MHz for different fluids. The performance of the TL is successfully validated using simulation and measurement results.</P>

Inkjet-Printed Electromagnet-Based Touchpad Using Spiral Resonators

Choi, Sungjin,Eom, Seunghyun,Tentzeris, Manos M.,Lim, Sungjoon Institute of Electrical and Electronics Engineers 2016 Journal of microelectromechanical systems Vol. No.

<P>In this paper, an inkjet-printed electromagnet-based touchpad employing spiral resonators is proposed. The proposed touchpad is fabricated by a direct patterning method using an inkjet printer with a conductive silver nanoparticle ink. The conductive patterns are easily printed on a paper substrate and sintered for achieving good conductivity. The proposed touchpad is composed of two spiral resonators that resonate at 0.94 GHz (f(1)) and 1.83 GHz (f(2)), respectively. When the first resonator is touched, f(1) decreases from 0.94 to 0.81 GHz because of electromagnetic (EM) coupling between the finger and the spiral resonator. Similarly, when the second resonator is touched, f(2) decreases from 1.83 to 1.55 GHz. Owing to the EM coupling distance between the spiral resonator and the finger, the frequency changes although the finger does not reach beyond a height of 1.27 mm on the spiral resonator. The performance of the proposed touchpad is validated using simulation and measurement results. [2016-0035]</P>

A Novel High-Gain Tetrahedron Origami

Shah, Syed Imran Hussain,Lee, Dongju,Tentzeris, Manos M.,Lim, Sungjoon IEEE 2017 IEEE antennas and wireless propagation letters Vol.16 No.-

<P>In this letter, a novel high-gain tetrahedron origami antenna is introduced. The antenna comprises a triangular-shaped monopole, a reflector, and two parasitic strip directors on a paper substrate. The directors and the reflector are employed to increase the antenna gain. The step-by-step origami folding procedure is presented in detail. The proposed design of antenna is verified by both simulations and measurements with a fabricated prototype. The antenna exhibits a 10-dB impedance bandwidth of 66% (2-4 GHz) and a peak gain of 9.5 dBi at 2.6 GHz.</P>

Silver Nanoparticle-Based Inkjet-Printed Metamaterial Absorber on Flexible Paper

Minyeong Yoo,Hyung Ki Kim,Sangkil Kim,Tentzeris, Manos,Sungjoon Lim IEEE 2015 IEEE antennas and wireless propagation letters Vol.14 No.-

<P>In this letter, a novel, flexible inkjet-printed metamaterial absorber is proposed. The unit cell consists of a miniaturized Jerusalem-cross resonator and a completely conductive bottom. Because the conductive patterns are inkjet-printed using silver nanoparticle inks on paper, the proposed metamaterial absorber is flexible. It is also eco-friendly because it does not produce any chemical waste. In this letter, the working principle of the proposed miniaturized unit cell is explained, and parametric simulations are described. The inkjet-printing process is delineated, and the silver nanoparticle inks and paper used are characterized. The performance of the proposed absorber is demonstrated with a full-wave simulation and measurements at the X-band. The experimental results show that the absorption rate at 9.09 GHz is greater than 99% at the normal incidence. Angular and polarization insensitivity are also experimentally demonstrated.</P>

Battery-free slotted patch antenna sensor for wireless strain and crack monitoring

Xiaohua Yi,Chunhee Cho,Yang Wang,Manos M. Tentzeris 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.6

In this research, a slotted patch antenna sensor is designed for wireless strain and crack sensing. An off-the-shelf RFID (radiofrequency identification) chip is adopted in the antenna sensor design for signal modulation. The operation power of the RFID chip is captured from wireless reader interrogation signal, so the sensor operation is completely battery-free (passive) and wireless. For strain and crack sensing of a structure, the antenna sensor is bonded on the structure surface like a regular strain gage. Since the antenna resonance frequency is directly related with antenna dimension, which deforms when strain occurs on the structural surface, the deformation/strain can be correlated with antenna resonance frequency shift measured by an RFID reader. The slotted patch antenna sensor performance is first evaluated through mechanics-electromagnetics coupled simulation. Extensive experiments are then conducted to validate the antenna sensor performance, including tensile and compressive strain sensing, wireless interrogation range, and fatigue crack sensing.

Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic

Kim, Il Kwon,Kingsley, N.,Morton, M.,Bairavasubramanian, R.,Papapolymerou, J.,Tentzeris, M.M.,Yook, Jong-Gwan IEEE 2005 IEEE transactions on microwave theory and techniqu Vol.53 No.9

In this paper, microstrip coupled-line bandpass filters using a Koch fractal shape are proposed for the first time. These filters are fabricated on a liquid crystal polymer (LCP) substrate for Ku-band. Conventional microstrip coupled-line filters are very popular for RF front ends because they can be fabricated easily. However, their large second harmonic causes the shape of the passband to be asymmetric in the upper band and it worsens the skirt properties. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shapes. In this paper, using LCP, the maximum harmonic suppression was almost 42 dB. This type of filter can be used to suppress the second harmonic without any additional devices and regardless of the substrate.