Showing papers presented at "International Workshop on Antenna Technology in 2012"

Wideband artificial magnetic conductors loaded with Non-Foster negative inductors

Abstract: We examine how the bandwidth of artificial magnetic conductors (AMC) can be greatly increased when loaded with negative-inductance Non-Foster circuits. This increase in bandwidth is achieved by enhancing the structural inductance of the AMC by combining it in parallel with a negative inductance, thus achieving a bandwidth that exceeds what is possible with passive approaches. A prototype VHF-UHF active AMC was fabricated and measured which achieved a bandwidth greater than 80% at resonant frequency of 263 MHz.

Flexible textile antennas for body-worn communication

Abstract: This paper presents an embroidered body-worn antenna using conductive fibers (E-fibers). The antenna's conductive surfaces were fabricated using precise and automated embroidering techniques to produce fully flexible and conformal antenna elements attached to regular fabrics and clothing. These E-fiber antennas offer desirable mechanical properties without undermining electrical performance for body-worn, on-clothing applications at radio frequencies (RF). In this study, we used an embroidered asymmetric meandered flare (AMF) dipole antenna to validate the textile antenna's performance. Its excellent RF performance was found comparable to conventional printed antennas. Therefore, these new E-fiber antennas may be integrated into scarves, handbags, shirts, coats or hand bands for convenient carefree health monitoring and wideband communications.

Metamaterials for wireless power transfer

Abstract: Recently, metamaterials have been developed for wireless power transfer applications. It has been shown that the near-field electromagnetic coupling between two resonant coils can be enhanced by a slab of metamaterial. With the assist of the metamaterial, the efficiency of wireless power transfer between the resonant coils can be greatly improved. In this paper, recent progress in this area will be presented: theoretical development of enhanced coil coupling with metamaterial will be briefly discussed; the design of metamaterial slabs for near-field wireless power transfer will be shown; recent experimental results on wireless power transfer efficiency improvement with metamaterial will also be presented.

Wireless passive sensor development for harsh environment applications

Abstract: Three researchers at University of Central Florida from electrical engineering, materials science, and mechanical engineering teamed together to develop high-temperature (> 1000°C) sensors for various harsh environment applications such as combustion turbines. In this paper, we will provide an overview of the recent progress in the development of sensing materials, sensor fabrication methods, and wireless sensing techniques.

Embroidered flexible RF electronics

Abstract: We introduce a novel class of flexible Radio Frequency (RF) electronics composed of conductive fibers on polymer or fabric substrates. The proposed fiber conductors and polymer substrates provide excellent RF characteristics, including mechanical flexibility and conformality. Key to the improved conductivity is the increased stitching density of the employed conductive fibers, reaching >70 stitches per cm2. Prototype flexible antennas and circuits were fabricated and validated for their RF performance. These were realized by embroidering them on organza fabrics or by integrating them on thin polymer substrates. Their RF performance was found comparable to their conventional copper counterparts. Because of their excellent RF performance and high level of flexibility, these embroidered antennas should lead to a new class of devices expected to provide high data rate, low profile, and reliable operation for RF applications.

Design of a cylindrical resonant cavity antenna for BAN applications at V band

Abstract: An antenna for on-body applications based on a cylindrical resonator is presented in this paper. The antenna is designed to work at V-band, specifically in the unlicensed bandwidth around 60GHz.The resonant cavity is obtained by means of a woodpile Electronic Band Gap (EBG) structure made of alumina, and exhibits an omnidirectional radiation pattern on the plane normal to the cylinder axis. Such characteristic is extremely important for on-body application, since it improves the signal coverage of the human surface while reducing the energy lost in off-body radiation.

Design and near-field characterization of a planar on-body UWB slot-antenna for stroke detection

Abstract: A planar UWB slot-antenna with a size of 35×35mm2 is proposed for stroke detection. The antenna is optimized for operation directly on human skin in the frequency range from 1 to 9 GHz. A sector-like slot is applied to the design to enhance the bandwidth regarding the current distribution. The near-field performance of the antenna is characterized and verified by the measurements. Benefiting from a symmetrical structure and differential feeding technique the antenna owns a very stable radiation behavior in the whole frequency range and a very high front-to-back ratio which would improve the stroke detection capability of the brain imaging system with robust performance.

UHF near-field segmented loop antennas with enlarged interrogation zone

Abstract: Near-field radio frequency identification (RFID) technology at ultra high frequency (UHF) bands is of increasingly interest because of its promising opportunities in item-level RFID applications. The conventional single solid-line loop antenna is unable to generate strong and uniform magnetic field within an electrically large interrogation zone at the UHF bands. Segmented loop antennas are promising for UHF near-field RFID applications since they are able to generate uniform and strong magnetic field in an electrically larger interrogation zone. The reported segmented loop antennas have been able to offer an interrogation zone with a perimeter of around two operating wavelengths. In this paper, the segmented loop antennas with enlarged interrogation zone are presented. Using dual or multiple segmented loop configurations, the perimeters of the interrogation zone of the antennas can be larger than three operating wavelengths at the UHF bands.

A wideband double dipole quasi-Yagi antenna using a microstrip-slotline transition feed

Abstract: This paper describes a wideband double dipole quasi-Yagi antenna fed by a microstrip-to-slotline transition. The transition feed consists of a microstrip radial stub and a slot radial stub, each with the same angle of 90°, but with different radii to achieve wideband impedance matching. Double dipoles with different lengths are utilized as primary radiation elements to enhance bandwidth and achieve stable radiation patterns. The antenna has a bandwidth of 3.65–8.90 GHz for a −10 dB reflection coefficient, and a flat gain of 6.4–7.6 dB across the bandwidth. The proposed antenna could be widely applicable to wideband wireless communication systems due to wideband characteristics, planar structure, and stable radiation pattern.

QFN based packaging concepts for millimeter-wave transceivers

Abstract: This paper introduces the idea of a low-cost surface-mountable millimeter-wave radar sensor. Different packaging topologies are compared with the potential of integrating the whole radar frontend together with the antennas into a single QFN package. The pros and cons of the different packaging concepts are discussed and finally, a 120 GHz off-chip antenna design for integration into a QFN package and its measurements are presented.

Towards a Smart Wireless Integrated Module (SWIM) on flexible organic substrates using inkjet printing technology for wireless sensor networks

Abstract: Wireless sensor networks (WSNs) have potential military, industrial, biomedical, environmental, and residential applications. However, implementing sensor networks and realizing their potential faces various challenges. Sensors nodes should be small in size, ultra-low-power, and WSNs should be comprised of large quantities of sensor nodes [1][2]. These challenges emphasize the need for low-cost and eco-friendly substrates suitable for mass production of wireless sensor nodes. Organic substrates is one of the leading solutions to realize ultra-low cost and eco-friendly sensor networks [3]. This paper presents the first IEEE 802.14.4 and ZigBee complaint wireless sensor node on organic substrates. The wireless node is a System-on-Package (SoP) solution operating at 2.4GHz with a printed Planar Inverted-F Antenna (PIFA) on organic substrates using inkjet printing technology. A prototype is realized on FR-4 substrate and used to compare traditional manufacturing techniques with an inkjet-printing solution on paper, which is promising in the large scale manufacturing of ultra-low-cost eco-friendly “green” wireless sensor networks.

An electrically small frequency reconfigurable antenna for DVB-H

Abstract: An electrically small frequency-reconfigurable antenna with a very wide tuning band is proposed. The antenna consists in a printed meandered monopole antenna loaded by varactor diodes. The radiating element has a size of 15*15*3 mm3 and is mounted on a 230*130mm2 ground plane. A thick block of a commercial magneto-dielectric material is inserted over the double-meandered antenna as a superstrate This antenna is able to maintain a return loss below −10 dB over 8 MHz bandwidth reconfigurable channel from 450 to 900 MHz without using any external matching circuit. The measured tuning range of the fabricated antenna reaches from 470–862MHz covering the whole frequency band specification of the DVB-H standard.

A voltage-boosting antenna for RF energy harvesting

Abstract: This paper presents the antenna to enhance DC output of RF energy harvesting system under weak signal reception environment. To select candidate sites and base stations for RF energy harvesting system, we discuss expected reception power level by a simple line-of-sight propagation model and the specification of currently used base stations. Under this site condition, this paper presents a voltage-boosting antenna consisting of a folded dipole antenna with high input impedance and rectifier circuit tuned for it. A theory of voltage-booting and a circuit design procedure are presented for FM radio signals.

THz photoconductive antennas in pulsed systems and CW systems

Abstract: In designing terahertz (THz) antennas with high output power and/or high optical-THz conversion efficiency, the photoconductor property is an important consideration. According to the type of the optical excitation, THz antennas can be divided into two categories: THz photoconductive antennas in a pulsed system and THz photomixing antennas in a Continuous-Wave (CW) system. How different excitation types can affect the performance of the antenna is an important issue in THz systems. Thus, the aim of this paper is to investigate and compare THz photoconductive antennas and THz photomixing antennas from an important design parameter point of view; namely the conductance of the photoconductive material substrate which acts as the source for a PC antenna. Through numerical analyses of example systems, it is shown that source resistance of a THz antenna in a CW system is greater than those in a pulsed system. Further, an important practical system setting, the dependency of alignment of two beams in CW systems on antenna gap size is also investigated. It is illustrated that mixing efficiency for large gap antennas is more sensitive to angle between two beams.

Design of an implantable antenna for WBAN applications

Abstract: In this paper, an implantable planar inverted-F antenna (PIFA) for an artificial cardiac pacemaker is proposed. The antenna has a simple structure with a low profile and is placed on the top side of the pacemaker. The dimension of the pacemaker system, including the antenna element, is 42 mm × 43.6 mm × 11 mm. When the antenna is embedded in pig tissue, −10 dB impedance bandwidth of the antenna is 6 MHz (399 ∼ 406 MHz). The proposed PIFA in tissue has a peak gain of −20.19 dBi and a radiation efficiency of 1.12 % at 403 MHz. When the proposed antenna is placed in a liquid flat phantom, its specific absorption ratio (SAR) value is 0.038 W/Kg (1 g tissue). Performances of the proposed PIFA is sufficient to operate at the MICS band (402 ∼ 405 MHz).

Ultra wideband antenna diversity techniques for on/off-body radio channel characterisation

Abstract: Diversity is powerful tool for combat fading. This paper presents experimental investigations and comparison of ultra wideband antenna diversity technique for on-body and off-body radio propagation channels. Diversity gain (DG) is calculated for five different channels namely: Access point (AP)/belt-to-head, AP/belt-to-chest, AP/belt-to-wrist, AP/belt-to-ankle and AP/belt-to-back with the subject performing realistic movements of different nature in an indoor environment. Results showed that almost 50% improvement in DG is obtained for off-body case as compared to on-body case, which shows the usefulness of UWB off-body diversity for body centric wireless communications.

An efficient, low-profile antenna employing lossy magneto-dielectric materials

Abstract: It has been shown that a magnetic core in a loop antenna excludes energy from the interior reducing radiation Q and that a core with magnetic losses still provides this reduction of stored energy without excessive dissipation provided that the magnitude of the complex permeability is sufficiently large. We present a broadband, low-loss, low-profile antenna based on a lossy magneto-dielectric material, a Ni-Zn ferrite operating in its dispersion region. The antenna behaves as a magnetic dipole and a radiation efficiency of almost 65 % is obtained at a frequency for which the loss tangent of the material is greater than 10.

Low-profile, high-permeability antennaless RFID tags for use on metal objects

Abstract: Radio-frequency identification (RFID) systems are used in asset tracking, but general-purpose tags typically do not perform well on or near metal. Therefore, custom solutions for on metal applications are common. Many solutions for on-metal tags use spacers or electromagnetic band-gap structures resulting in designs that are extremely thick. Our approach was to incorporate materials with permeabilities greater than 1 to create an impedance across a metal surface, diverting current into the tag IC. This type of tag is nearly antennaless as it uses the ground plane or container to excite currents through the IC. Our research has shown that these tags are sensitive to several parameters, such as the size and shape of the plane upon which they are placed, the material used in the antenna, and the type of matching network being used. Tags using magnetic materials in this manner are significantly thinner than those developed using other methods.

Terahertz array receivers with integrated antennas

Abstract: Highly sensitive terahertz heterodyne receivers have been mostly single-pixel. However, now there is a real need of multi-pixel array receivers at these frequencies driven by the science and instrument requirements. In this paper we explore various receiver font-end and antenna architectures for use in multi-pixel integrated arrays at terahertz frequencies. Development of wafer-level integrated terahertz receiver front-end by using advanced semiconductor fabrication technologies has progressed very well over the past few years. Novel stacking of micro-machined silicon wafers which allows for the 3-dimensional integration of various terahertz receiver components in extremely small packages has made it possible to design multi-pixel heterodyne arrays. One of the critical technologies to achieve fully integrated system is the antenna arrays compatible with the receiver array architecture. In this paper we explore different receiver and antenna architectures for multi-pixel heterodyne and direct detector arrays for various applications such as multi-pixel high resolution spectrometer and imaging radar at terahertz frequencies.

Broadband 60-GHz beam-steering vertical off-center dipole antennas in LTCC

Abstract: Broadband 60-GHz vertical off-center dipole antenna and its arrays in low-temperature co-fired ceramic (LTCC) substrate are presented in this paper. The dipole antenna is designed using the off-center-fed technology to improve its bandwidth to cover the 60-GHz frequency band from 57 GHz to 66 GHz. A 4×4 planar array is optimized to achieve a maximum gain of 15.6 dBi at 60 GHz, while a beam-steering array using a low-cost Butler matrix is optimized to give a 5-dB measured beamwidth wider than 80° at 60 GHz. Measured results verified our prediction.

Active electromagnetic structures, metamaterials, and antennas

Abstract: If we are limited to rearranging passive materials such as dielectrics and metals, then the performance of antennas, artificial materials, and other electromagnetic structures that we build will always be determined by the same fundamental limitations that affect today's designs. By including active circuits, it is possible to exceed the limitations of passive structures and to build materials and devices that are not otherwise possible. One example is a thin, broadband leaky wave antenna that is free of beam squint. This structure can also be used as a broadband, electrically thin cloaking structure. Another example is a broadband parasitic array that does not suffer from bandwidth limitations caused by the delay between the elements. We have demonstrated several new concepts based on active electromagnetic structures, and have successfully implemented the non-Foster circuits that are necessary to realize them.

Conformal slotted waveguide array antenna

Abstract: A new slotted rectangular waveguide array antenna is introduced, which is constructed on the conformal cylindrical surface. Unlike other slotted waveguide arrays, this array has a beam with a large tilt angle from the broadside of the linear array. The array consists of a waveguide with inclined slots cutting in the narrow wall and a matching load at one end for the traveling wave operation. The antenna is designed and built using the analytical procedure combining with the commercial software. The radiation patterns and gain of the antenna are measured, and the experimental data obtained are compared with the theoretical results.

CPW fed 2 × 2 patch array for D-band System-in-Package applications

Abstract: A 2×2-patch array for System-in-Package radar sensors at 122 GHz is presented in this paper. The antenna is realized on a 127 µm thick Alumina substrate and fed by a coplanar-waveguide (cpw) which allows direct attachment to a monolithic millimeter-wave integrated circuit (MMIC) as well as a probe-based measurement of the antenna. The design of the microstrip-fed patch array itself and the cpw-to-microstrip transition are explained. Measured results of gain, radiation pattern and return loss are presented, showing good agreement to simulation.

Antenna technology: Past, present and future

Abstract: The evolution of antenna technology is reviewed, from the days of Marconi to the present. Various periods over which antenna technology has been revitalized are reviewed, and the various antenna configurations developed during those periods are summarized along with some of their respective key characteristics. The history starts at the beginning of the 20th century and the respective technologies developed in the decades that follow are identified. Individuals that played a key role, especially during the early stages of antenna technology, are identified. Future trends and needs are speculated. Key technologies that will contribute to future advancements are identified and will be presented at the conference.

Design of an EBG Compact Low-Mass Antenna in C-band with dual circular polarisation

Abstract: Global transmission communication systems from geostationary orbit require compact and light antennas to reduce as much as possible the overall mass of the on flight configuration. Within the frame of the ESA project Compact Low-Mass Global Antennas, EADS CASA Espacio and the Public University of Navarra are developing a light and compact C-band antenna with dual circular polarization. The design of the antenna is based on flat planar technology, leading to two different lines of work. The first one consists in a low profile patch array while the other is based on Electromagnetic Band Gap (EBG) superstrate technology. Both configurations are studied and traded-off for single band working modes in C-band at 3.7 GHz. They are evaluated in terms of compactness, mass and RF performance. The array layout and beam forming network implementation are detailed, as well as the radiator and EBG superstrate selection.

Dual-band RFID tags based on folded dipole antennas loaded with spiral resonators

Abstract: The purpose of this paper is to demonstrate the possibility of implementing folded dipole antennas operative at two closely spaced frequencies of interest, for instance, in ultra-high-frequency radio frequency identification (UHF-RFID) applications. The dual-band functionality is achieved by coupling a spiral resonator to the antenna, which operates as an unbalanced transmission line. This modifies the impedance of the antenna and dual-band functionality can be achieved by virtue of the conjugate matching between the antenna and the chip at the frequencies of interest. Two prototype devices have been designed and fabricated: a mono-band folded dipole UHF-RFID tag, and a dual-band UHF-RFID tag based on a spiral resonator coupled to a folded dipole antenna. The measured read ranges at the operating frequencies are in the vicinity of 6 m. The read ranges of the designed tags have been also measured by attaching them to different objects (a CD-ROM box and a plastic ID card). A certain frequency shift is obtained, but this shift can be corrected by merely modifying the distance between the resonator and the antenna.

Combining metamaterial-inspired electrically small antennas with electromagnetic band gap (EBG) structures to achieve higher directivities and bandwidths

Abstract: We have developed a variety of electrically small, low-profile, planar, near-field resonant parasitic (NFRP) antennas [1], [2], [3], [4] These NFRP antennas have been generally designed on a ground plane with a low-profile footprint, but not conformal above a ground plane Furthermore, being electrically small, their directivities and bandwidths are approximately equal to those of an infinitesimal dipole Many wireless applications demand higher directivities and increased bandwidths with a conformal form factor This contribution further develops these metamaterial-inspired NFRP antenna designs to incorporate electromagnetic band gap (EBG) structures to achieve higher directivities and bandwidths

Study on the dual polarizations of the active cylindrical coated nano-particle antennas

Abstract: The EM polarization properties of the active cylindrical coated nano particle antennas are investigated in the visible frequency band. It is observed that the active cylindrical coated nano particle could be illuminated by plane waves with horizontal polarization or vertical polarization, and show the dipole mode, although the resonant size of the particles are little different. Especially, when the vertical polarization plane wave incident to the particle with 45o rotation angle, it still show the dipole mode, the electrical field and power flow are symmetrical along the particle axis, and looks like a combination of the horizontal polarization mode and vertical polarization mode.

Planar antennas on Integrated Passive Device technology for biomedical applications

Abstract: In this paper, we present the design of electrically small antennas for biomedical application at 2.4 GHz. Performance of two different antennas built using the Integrated Passive Devices (IPD) technology from STMicroelectronics is investigated. Two monopoles miniaturized with the meandered technique are studied. Their quality factor Q z is calculated from their input impedance and compared with the quality factor limits for planar antennas given by Gustafsson. Therefore, we determine which configuration offers the best trade-off between radiation efficiency and quality factor Q z .

Dual-band radio-frequency device for sensing dielectric property changes in microfluidic channel

Abstract: We propose a dual-band RF device to detect the dielectric changes in polydimethylsiloxane (PDMS) microfluidic channel. Such a device, which consists of two dual-band Wilkinson power dividers (working at 2Ghz and 5GHz) and two 90° dual-band microstrip lines (providing 180° phase difference at two working frequencies), is very sensitive for identifying dielectric material changes. Moreover, by operating at two frequencies simultaneously, it can improve the measurement stability/robustness. Compared with the recently reported RF microfluidic sensor [Yang et al, Lab Chip, 10, 553, (2010)], the proposed device features enhanced measurement stability with the same level of measurement sensitivity (−80dB cancellation level).