Showing papers on "Antenna (radio) published in 2017"

Multibeam Antenna Technologies for 5G Wireless Communications

Abstract: With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Millimeter-Wave 5G Antennas for Smartphones: Overview and Experimental Demonstration

Abstract: For the first time to the best of our knowledge, this paper provides an overview of millimeter-wave (mmWave) 5G antennas for cellular handsets. Practical design considerations and solutions related to the integration of mmWave phased-array antennas with beam switching capabilities are investigated in detail. To experimentally examine the proposed methodologies, two types of mesh-grid phased-array antennas featuring reconfigurable horizontal and vertical polarizations are designed, fabricated, and measured at the 60 GHz spectrum. Afterward the antennas are integrated with the rest of the 60 GHz RF and digital architecture to create integrated mmWave antenna modules and implemented within fully operating cellular handsets under plausible user scenarios. The effectiveness, current limitations, and required future research areas regarding the presented mmWave 5G antenna design technologies are studied using mmWave 5G system benchmarks.

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications

Abstract: In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.

5G Millimeter-Wave Antenna Array: Design and Challenges

Abstract: As there has been an explosive increase in wireless data traffic, mmw communication has become one of the most attractive techniques in the 5G mobile communications systems. Although mmw communication systems have been successfully applied to indoor scenarios, various external factors in an outdoor environment limit the applications of mobile communication systems working at the mmw bands. In this article, we discuss the issues involved in the design of antenna array architecture for future 5G mmw systems, in which the antenna elements can be deployed in the shapes of a cross, circle, or hexagon, in addition to the conventional rectangle. The simulation results indicate that while there always exists a non-trivial gain fluctuation in other regular antenna arrays, the circular antenna array has a flat gain in the main lobe of the radiation pattern with varying angles. This makes the circular antenna array more robust to angle variations that frequently occur due to antenna vibration in an outdoor environment. In addition, in order to guarantee effective coverage of mmw communication systems, possible solutions such as distributed antenna systems and cooperative multi-hop relaying are discussed, together with the design of mmw antenna arrays. Furthermore, other challenges for the implementation of mmw cellular networks, for example, blockage, communication security, hardware development, and so on, are discussed, as are potential solutions.

Current Misuses and Future Prospects for Printed Multiple-Input, Multiple-Output Antenna Systems [Wireless Corner]

Abstract: In the past six years or so, the number of scientific articles and conference papers providing possible multiple-input, multiple-output (MIMO) antenna system solutions has noticeably increased. Flagship conferences on antennas and propagation have recently had multiple sessions addressing MIMO antenna systems and their applications. The importance of such antenna systems lies in the magnitude of their application in current wireless devices and gadgets, and this thrust will continue because fourth-generation (4G) and the upcoming fifth-generation (5G) wireless standards rely heavily on MIMO technology. But throughout the years, and up until now, a wide range of publications still suffer from some major misconceptions and unclear understanding of the fundamental aspects while designing, characterizing, and evaluating such multiantenna systems.

Two Asymmetrically Mirrored Gap-Coupled Loop Antennas as a Compact Building Block for Eight-Antenna MIMO Array in the Future Smartphone

Abstract: A compact two-antenna building block for forming the multiple-input multiple-output (MIMO) array in the mobile device such as the smartphone is presented. The building block has a planar structure of small size $7 \times 10$ mm2 (about $0.08\lambda \times 0.12\lambda$ ) for operating at 3.5-GHz band (3.4–3.6 GHz), which is the recently identified frequency spectrum in World Radiocommunication Conference 2015 for future broadband mobile services. The building block is formed by two gap-coupled loop antennas having asymmetrically mirrored (AM) structures with respect to the system ground plane of the smartphone. The two AM antennas show good isolation thereof and their envelope correlation coefficient is much less than 0.1 in the operating band, showing very good independence of the two antennas in their far-field radiation characteristics. By using four such building blocks, an eight-antenna MIMO array at 3.5-GHz band in the smartphone is easily implemented. The channel capacity of the eight-antenna MIMO array in an $8 \times 8$ MIMO system is calculated to be about 36 b/s/Hz with 20-dB signal-to-noise ratio. The measured channel capacity obtained using an $8 \times 8$ MIMO measurement setup is also presented, which generally agrees with the calculated results. The obtained eight-antenna MIMO array is promising for future or fifth-generation smartphone applications.

Acoustically actuated ultra-compact NEMS magnetoelectric antennas.

Abstract: State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1–2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems. The miniaturization of antennas beyond a wavelength is limited by designs which rely on electromagnetic resonances. Here, Nan et al. have developed acoustically actuated antennas that couple the acoustic resonance of the antenna with the electromagnetic wave, reducing the antenna footprint by up to 100.

Array-Antenna Decoupling Surface

Abstract: Massive multiple-input multiple-output (M-MIMO) technology is considered to be a key enabling technology for future wireless communication systems. One of the challenges in effectively implementing an advanced precoding scheme to a large-scale array antenna is how to reduce the mutual coupling among antenna elements. In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time. An ADS is a thin surface that is composed of a plurality of electrical small metal patches and is placed in front of the array antenna. The partially diffracted waves from the ADS can be controlled to cancel the unwanted coupled waves. Two practical design examples are given to illustrate the design process and considerations, and to demonstrate the usefulness of ADS for the applications of phased array antennas and M-MIMO systems when commonly used precoding schemes are applied. The attractive features of ADS include its applicability to a large-scale array antenna; suitability for a wide range of antenna forms; wide decoupling bandwidth; and simplicity in implementation.

A novel millimeter-wave channel simulator and applications for 5G wireless communications

Abstract: This paper presents details and applications of a novel channel simulation software named NYUSIM, which can be used to generate realistic temporal and spatial channel responses to support realistic physical-and link-layer simulations and design for fifth-generation (5G) cellular communications. NYUSIM is built upon the statistical spatial channel model for broadband millimeter-wave (mmWave) wireless communication systems developed by researchers at New York University (NYU). The simulator is applicable for a wide range of carrier frequencies (500 MHz to 100 GHz), radio frequency (RF) bandwidths (0 to 800 MHz), antenna beamwidths (7° to 360° for azimuth and 7° to 45° for elevation), and operating scenarios (urban microcell, urban macrocell, and rural macrocell), and also incorporates multiple-input multiple-output (MIMO) antenna arrays at the transmitter and receiver. This paper also provides examples to demonstrate how to use NYUSIM for analyzing MIMO channel conditions and spectral efficiencies, which show that NYUSIM is an alternative and more realistic channel model compared to the 3rd Generation Partnership Project (3GPP) and other channel models for mmWave bands.

Guided wave communication system with interference cancellation and methods for use therewith

Abstract: In accordance with one or more embodiments, a transmission device includes a receiver configured to receive an interfering signal via an antenna. A transmitter is configured to generate first electromagnetic signals conveying first data. A coupler is configured to generate first guided electromagnetic waves in response to combined electromagnetic signals, wherein the first guided electromagnetic waves propagate, without requiring an electrical return path, along a surface of a transmission medium of a distributed antenna system. A cancellation circuit is configured to generate the combined electromagnetic signals, based on the interfering signal and the first electromagnetic signals, wherein the combined electromagnetic signals mitigate interference by the interfering signal with the first guided electromagnetic waves.

Dual mode communications device and methods for use therewith

Abstract: In accordance with one or more embodiments, a communication device includes a dual-band antenna array configured to communicate RF signals in an RF band and to communicate MMW signals in a MMW frequency band with a remote device At least one transceiver is configured to generate the RF signals conveying a command to the remote device to transmit probe signals in the MMW frequency band, to receive the probe signals via the dual-band antenna in the MMW frequency band, and is initialized with first antenna beam steering parameters to facilitate a first antenna beam of the dual-band antenna array for the operation in the MMW frequency band A controller is configured to generate the first antenna beam steering parameters based on the probe signals and to generate the control signal to switch the dual-band antenna array to the operation in the MMW frequency band after transmission of the RF signals

Apparatus and methods for wireless communications

Abstract: Aspects of the subject disclosure may include, a communication device having a dielectric antenna, a radio housing, a hollow waveguide and an antenna stabilizer. The radio housing can enclose a transmitter that generates electromagnetic waves. The hollow waveguide can have a cavity therethrough to facilitate transmission of the electromagnetic waves to a feed point of the dielectric antenna for guidance of the electromagnetic waves without requiring an electrical return path, where the electromagnetic waves generate near-field wireless signals. The antenna stabilizer can facilitate coupling the hollow waveguide to the feed point of the dielectric antenna. Other embodiments are disclosed.

Method and apparatus for use with a radio distributed antenna having a fiber optic link

Abstract: Aspects of the subject disclosure may include, for example, a transceiver that converts first modulated channel signals in a first spectral segment to the first modulated channel signals in a second spectral segment based on signal processing of the first modulated channel signals and without modifying the signaling protocol of the first modulated channel signals. The transceiver transmits, via a fiber optic cable, a transmission signal including a first reference signal with the first modulated channel signals in the second spectral segment to a network element of a plurality of network elements of the distributed antenna system for wireless distribution of the first modulated channel signals to mobile communication devices in the first spectral segment. The first reference signal enables the distributed antenna system to reduce a phase error during processing of the first modulated channel signals from the second spectral segment to the first spectral segment.

Coverage Analysis for Millimeter Wave Networks: The Impact of Directional Antenna Arrays

Abstract: Millimeter wave (mm-wave) communications is considered a promising technology for 5G networks. Exploiting beamforming gains with large-scale antenna arrays to combat the increased path loss at mm-wave bands is one of the defining features. However, previous works on mm-wave network analysis usually adopted oversimplified antenna patterns for tractability, which can lead to significant deviation from the performance with actual antenna patterns. In this paper, using tools from stochastic geometry, we carry out a comprehensive investigation on the impact of directional antenna arrays in mm-wave networks. We first present a general and tractable framework for coverage analysis with arbitrary distributions for interference power and arbitrary antenna patterns. It is then applied to mm-wave ad hoc and cellular networks, where two sophisticated antenna patterns with desirable accuracy and analytical tractability are proposed to approximate the actual antenna pattern. Compared with previous works, the proposed approximate antenna patterns help to obtain more insights on the role of directional antenna arrays in mm-wave networks. In particular, it is shown that the coverage probabilities of both types of networks increase as a non-decreasing concave function with the antenna array size. The analytical results are verified to be effective and reliable through simulations, and numerical results also show that large-scale antenna arrays are required for satisfactory coverage in mm-wave networks.

Antenna structure with circularly polarized antenna beam

Abstract: In accordance with one or more embodiments, a communication device includes a dielectric antenna having a feed point and an aperture. A cable comprising a conductorless core is coupled to the feed point of the dielectric antenna. A transmitter is coupled to the cable and facilitates a transmission of first electromagnetic waves to the feed point of the dielectric antenna. The first electromagnetic waves are guided by the conductorless core and propagate along the conductorless core without requiring an electrical return path, and the first electromagnetic waves generate free-space wireless signals from the aperture of the antenna in accordance with a circularly polarized antenna beam pattern.

Dual mode communications device with null steering and methods for use therewith

Abstract: In accordance with one or more embodiments, a communication device includes a dual-band antenna array configured to transmit first radio frequency (RF) signals to a remote device in an RF band and to transmit first millimeter wave (MMW) signals to the remote device in a MMW frequency band, wherein the MMW frequency band is above the RF band. A base transceiver station is configured to generate a consolidated steering matrix in accordance with the transmission of the first RF signals to the remote device in the RF band. A remote radio head is configured to convert the consolidated steering matrix to a converted steering matrix that facilitates the transmission of the first MMW signals to the remote device in the MMW frequency band via the dual-band antenna array in accordance with an antenna beam pattern having at least one selected null direction, and further configured to generate the first MMW signals in accordance with the converted steering matrix.

Antenna structure with doped antenna body

Abstract: In accordance with one or more embodiments, a communication device includes a dielectric antenna having a body of first dielectric material doped with particles of a second dielectric material. A cable comprising a dielectric core is coupled to a feed point of the dielectric antenna. A transmitter, coupled to the cable, facilitates a transmission of electromagnetic waves, the electromagnetic waves are guided by the dielectric core to the feed point of the dielectric antenna, without requiring an electrical return path.

Multimode antenna system and methods for use therewith

Abstract: In accordance with one or more embodiments, a communication device includes an antenna having a feed point and an aperture. A feedline is coupled to the feed point of the dielectric antenna. A multi-input multi-output (MIMO) transceiver is coupled to feedline, the MIMO transceiver facilitating a transmission of first electromagnetic waves to the feed point of the antenna, wherein the first electromagnetic waves are guided by the feedline, wherein the first electromagnetic waves propagate along the feedline via a plurality of guided wave modes without requiring an electrical return path, wherein the first electromagnetic waves convey first data in accordance with one or more MIMO techniques and wherein the first electromagnetic waves generate first free-space wireless signals at the aperture of the antenna in accordance with the one or more MIMO techniques.

Antenna system with planar antenna and directors and methods for use therewith

Abstract: Aspects of the subject disclosure may include a planar antenna configured to transmit first signals as a first guided electromagnetic wave that is bound to a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path, wherein the planar antenna includes an array of patch antennas that generates first near field signals in response to the first signals and a plurality of directors configured to guide a portion of the first near field signals from the array of patch antennas to the surface of the transmission medium, and wherein the portion of the first near field signals combines to induce the first guided electromagnetic wave that is bound to the surface of the transmission medium.

Dual mode antenna systems and methods for use therewith

Abstract: Aspects of the subject disclosure may include an antenna having a feedline configured to receive a first signal and a second signal. A dielectric antenna body is configured to transmit the first signal as a first free space wireless signal and further configured to transmit the second signal as a first guided electromagnetic wave that is bound to a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path. Other embodiments are disclosed.

The Random Frequency Diverse Array: A New Antenna Structure for Uncoupled Direction-Range Indication in Active Sensing

Abstract: In this paper, we propose a new type of array antenna, termed the random frequency diverse array (RFDA), for an uncoupled indication of target direction and range with low system complexity. In RFDA, each array element has a narrow bandwidth and a randomly assigned carrier frequency. The beampattern of the array is shown to be stochastic but thumbtack-like, and its stochastic characteristics, such as the mean, variance, and asymptotic distribution are derived analytically. Based on these two features, we propose two kinds of algorithms for signal processing. One is matched filtering, due to the beampattern's good characteristics. The other is compressive sensing, because the new approach can be regarded as a sparse and random sampling of target information in the spatial-frequency domain. Fundamental limits, such as the Cramer–Rao bound and the observing matrix's mutual coherence, are provided as performance guarantees of the new array structure. The features and performances of RFDA are verified with numerical results.

Guided wave communication system with resource allocation and methods for use therewith

Abstract: In accordance with one or more embodiments, a transmission device includes a receiver configured to receive an interfering signal via an antenna. A controller is configured to generate interference data based on the interfering signal. A communications interface is configured to send the interference data to a network element of a network and further configured to receive an allocation of a plurality of guided electromagnetic wave resource blocks. A transmitter is configured to generate electromagnetic signals conveying data, in accordance with the allocation of the plurality of guided electromagnetic wave resource blocks. A coupler configured to generate guided electromagnetic waves in response to the electromagnetic signals, wherein the guided electromagnetic waves propagate, without requiring an electrical return path, along a surface of a transmission medium of a distributed antenna system.

A Dual-Port Triple-Band L-Probe Microstrip Patch Rectenna for Ambient RF Energy Harvesting

Abstract: A dual-port triple-band L-probe microstrip patch rectenna design for ambient RF energy harvesting using the GSM-900, GSM-1800, and UMTS-2100 bands is described. The compact dual-port L-probe patch antenna is implemented by stacking two single-port patch antennas back to back. Each port can independently harvest RF signal from a half-space with gain greater than 7 dBi, and together with both ports in a dc combining configuration, the antenna can acquire RF energy from nearly all directions. We also provide a design for a high-efficiency triple-band rectifier operating at GSM-900, GSM-1800, and UMTS-2100, which is replicated on each port and concatenated together to allow dc combining and near doubling of the output dc voltage. Measurement results show that our prototyped dual-port triple-band rectenna can receive RF power from nearly all directions with an efficiency of greater than 40% and an output voltage of more than 600 mV when the power density is greater than 500 $\mu \mathrm{W}/\mathrm{m}^{2}$ .

Guided wave communication system with interference mitigation and methods for use therewith

Abstract: In accordance with one or more embodiments, a transmission device includes a receiver configured to receive an interfering signal via an antenna A controller is configured to select a subset of a plurality of guided electromagnetic wave resource blocks, based on the interfering signal, to mitigate an interference with a distributed antenna system A transmitter is configured to generate electromagnetic signals conveying data, in accordance with the subset of the plurality of guided electromagnetic wave resource blocks A coupler is configured to generate guided electromagnetic waves in response to the electromagnetic signals, wherein the guided electromagnetic waves propagate, without requiring an electrical return path, along a surface of a transmission medium of a distributed antenna system

Antenna system with planar antenna and methods for use therewith

Abstract: Aspects of the subject disclosure may include a planar antenna configured to transmit first signals as a first guided electromagnetic wave that is bound to a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path, wherein the planar antenna includes an array of patch antennas that generates first near field signals in response to the first signals, and wherein a portion of the first near field signals combines to induce the first guided electromagnetic wave that is bound to the surface of the transmission medium.

Mixer-Duplexer-Antenna Leaky-Wave System Based on Periodic Space-Time Modulation

Abstract: We present a mixer-duplexer-antenna leaky-wave system based on periodic space-time modulation. This system operates as a full transceiver, where the upconversion and downconversion mixing operations are accomplished via space-time transitions; the duplexing operation is induced by the nonreciprocal nature of the structure, and the radiation operation is provided by the leaky-wave nature of the wave. A rigorous electromagnetic solution is derived for the dispersion relation and field distributions. The system is implemented in the form of a spatio-temporally modulated microstrip leaky-wave structure incorporating an array of subwavelengthly spaced varactors modulated by a harmonic wave. In addition to the overall mixer-duplexer-antenna operation, frequency beam scanning at fixed input frequency is demonstrated as one of the interesting features of the system. A prototype is realized and demonstrated by full-wave and experimental results.

Position and Orientation Estimation through Millimeter Wave MIMO in 5G Systems

Abstract: Millimeter wave signals and large antenna arrays are considered enabling technologies for future 5G networks. While their benefits for achieving high-data rate communications are well-known, their potential advantages for accurate positioning are largely undiscovered. We derive the Cramer-Rao bound (CRB) on position and rotation angle estimation uncertainty from millimeter wave signals from a single transmitter, in the presence of scatterers. We also present a novel two-stage algorithm for position and rotation angle estimation that attains the CRB for average to high signal-to-noise ratio. The algorithm is based on multiple measurement vectors matching pursuit for coarse estimation, followed by a refinement stage based on the space-alternating generalized expectation maximization algorithm. We find that accurate position and rotation angle estimation is possible using signals from a single transmitter, in either line-of- sight, non-line-of-sight, or obstructed-line-of-sight conditions.

Compact Tapered Slot Antenna Array for 5G Millimeter-Wave Massive MIMO Systems

Abstract: A low-complexity metallic tapered slot antenna (TSA) array for millimeter-wave multibeam massive multiple-input multiple-output communication is proposed in this paper. Good beamforming performance can be achieved by the developed antenna array because the element spacing can easily meet the requirement of half-wavelength in the H-plane. The antenna element is fed by a substrate-integrated waveguide, which can be directly integrated with the millimeter-wave circuits. The proposed TSA is fabricated and measured. Measured results show that the reflection coefficient is lower than −15 dB Voltage Standing Wave Ratio ((VSWR) ≤ 1.45) within the frequency range from 22.5 to 32 GHz, which covers the 24.25–27.5-GHz band proposed by International Telecommunications Union (ITU) and the 27.5–28.35-GHz band proposed by Federal Communications Commission (FCC) for 5G. The gain of the antenna element varies from 8.2 to 9.6 dBi over the frequency range of 24–32 GHz. The simulated and measured results also illustrate good radiation patterns across the wide frequency band (24–32 GHz). A $1\times 4$ H-plane array integrated with the multichannel millimeter-wave transceivers on one PCB is demonstrated and excellent performance is achieved.

60-GHz Millimeter-Wave Channel Measurements and Modeling for Indoor Office Environments

Abstract: The millimeter-wave (mmWave) band will be used for the fifth-generation communication systems. In this paper, 60-GHz mmWave channel measurements and modeling are carried out for indoor office environments. The rotated directional antenna-based method and uniform virtual array-based method are adopted and compared to investigate the 60-GHz channel in a 3-D space, simultaneously covering azimuth and coelevation domains. The multipath component parameters including power, delay, azimuth, and elevation angles are estimated with the space-alternating generalized expectation–maximization estimation algorithm, and then processed with the K-means clustering algorithm. An extended Saleh–Valenzuela model with both delay and angular cluster features is used to characterize the measured channel, and the intercluster and intracluster parameters are extracted. We find that the azimuth departure angles are diverse and highly related to the antenna position and measurement environment, while the elevation departure angles are more related to the antenna height difference and confined in a relatively small direction range. The azimuth angle spread is much larger than the elevation angle spread either in global level or in cluster level. The results agree with the studies in the literature and channel models in IEEE standards.

Method and apparatus for communication using variable permittivity polyrod antenna

Abstract: Aspects of the subject disclosure may include, a device with a polyrod antenna having a core, where the core has a first region with a first dielectric constant and a second region with a second dielectric constant, and where the second dielectric constant is higher than the first dielectric constant. The device can include a waveguide coupled with the core, where the waveguide is configured to confine an electromagnetic wave at least in part within the core in the first region. Other embodiments are disclosed.