Integrated Antenna Research Articles

On-chip surface-enhanced Raman spectroscopy using nanosphere-lithography patterned antennas on silicon nitride waveguides.

A hybrid integration of nanoplasmonic antennas with silicon nitride waveguides enables miniaturized chips for surface-enhanced Raman spectroscopy at visible and near-infrared wavelengths. This integration can result in high-throughput SERS assays on low sampling volumes. However, current fabrication methods are complex and rely on electron-beam lithography, thereby obstructing the full use of an integrated photonics platform. Here, we demonstrate the electron-beam-free fabrication of gold nanotriangles on deep-UV patterned silicon nitride waveguides using nanosphere lithography. The localized surface-plasmon resonance of these nanotriangles is optimized for Raman excitation at 785 nm, resulting in a SERS substrate enhancement factor of 2.5 × 105. Furthermore, the SERS signal excited and collected through the waveguide is as strong as the free-space excited and collected signal through a high NA objective.

High‐gain low‐cost broadband 60 GHz differential integrated patch array antennas with wire‐bonding packaging and on‐board compensation network

Two high-gain broadband 60GHz integrated planar patch array antennas, without and with air cavity, are designed and implemented on Rogers 5880 substrate. The differential antenna structure is used to improve the signal integrity at millimetre-wave frequencies. The antennas are co-designed with bonding wires of which the parasitic effect is compensated using a passive network. The proposed antennas have the advantages of symmetrical radiation pattern, wide bandwidth and low insertion loss. In the measurement, a differential transmission line based de-embedding structure is developed on silicon, mimicking the real chip packaging environment and providing reliable terminations for antennas. The measured fractional bandwidths (| S 11 | <; -10dB) are 13.8 and 26.2%, respectively, for the two structures without and with air cavity, including the effect of a waveguide-to-microstrip line transition and a branch-line balun. Both antennas have measured gain of about 12 dBi. After de-embedding the return loss, the measured insertion loss of the bond wire compensation network is only 0.07dB at 61GHz.

An X-band bifunctional antenna using anisotropic transparent meta-surface

An integration of a transmitarray antenna and a beam-steering antenna has been achieved and experimentally demonstrated. The antenna system operating at X-band (8–12 GHz) is implemented by a well-optimized transparent meta-surface and launched by polarization-controlled feed antennas. The transparent meta-surface, with polarization-independent property, consists of 12 × 12 elements with a parabolic phase distribution at y-direction and a linear phase gradient at x = direction, respectively. Illuminating the meta-surface with differently-polarized electromagnetic waves, anomalous phenomena of beam bending and focusing are clearly observed. The performances of the antenna system are investigated in depth through near-field analysis and far-field measurements. Numerical and experimental results coincide well, indicating that the proposed antenna system advances in many aspects such as bifuncional radiation patterns, a broad bandwidth and also a simple fabrication process based on the convenient print circuit board (PCB) technology.

Structure of the plant photosystem I supercomplex at 2.6 Å resolution.

Four elaborate membrane complexes carry out the light reaction of oxygenic photosynthesis. Photosystem I (PSI) is one of two large reaction centres responsible for converting light photons into the chemical energy needed to sustain life. In the thylakoid membranes of plants, PSI is found together with its integral light-harvesting antenna, light-harvesting complex I (LHCI), in a membrane supercomplex containing hundreds of light-harvesting pigments. Here, we report the crystal structure of plant PSI-LHCI at 2.6 Å resolution. The structure reveals the configuration of PsaK, a core subunit important for state transitions in plants, a conserved network of water molecules surrounding the electron transfer centres and an elaborate structure of lipids bridging PSI and its LHCI antenna. We discuss the implications of the structure for energy transfer and the evolution of PSI.

A microstrip wideband monopole antenna for multisystem integration by utilizing stepped-impedance structure and L-shaped slot

In this article, a coplanar-waveguide (CPW)-fed dual-band antenna for applications of the multisystem integration has been demonstrated. The resonance analysis of the stepped-impedance (SI) monopole is presented by using the transmission-line analysis method. The frequency-response characteristics of the SI-monopole, such as the resonance condition and harmonic response, are systematically summarized. Furthermore, utilizing several simple techniques, such as bent feeding topology, asymmetric ground plane, and an L-shaped slot etched in the ground plane, a right-hand circularly polarized (RHCP) radiating wave at 1.57 GHz and a left-hand circularly polarized (LHCP) radiating wave at 2.33 GHz are excited for the applications of the global positioning system (GPS) and the satellite digital audio radio (SDAR) service system. After optimization of the geometrical parameters of the proposed antenna, the measured impedance bandwidths of a reflection coefficient less than −10 dB range from 1.40 to 2.98 GHz and from 4.48 to 6.27 GHz, and thus covers most of the commercial wireless communication systems, such as GPS, digital cellular system (DCS), personal communication system (PCS), international mobile telecommunications (IMT)−2000, wireless local area networks (WLAN), and long-term evolution (LTE) 2300/2600. The measured 3-dB axial ratio (AR) bandwidths are about 80 MHz at 1.57 GHz and 100 MHz at 2.33 GHz.

INTERMODULATION DISTORTION AND COMPRESSION POINT MEASUREMENT OF ACTIVE INTEGRATED ANTENNAS USING A RADIATIVE METHOD

In this paper, a measurement procedure allowing the characterization of active integrated antennas in terms of intermodulation distortion and compression point inside of a parallel plate cell is presented. The validity of the radiative measurement is shown and compared to the traditional guided procedure. A good agreement between the two methods shows that this approach allows the evaluation of the overall linearity behavior of arbitrary complex integrated antennas and can serve as a complementary tool when the traditional guided method cannot be applied. © 2017, Electromagnetics Academy. All rights reserved.

A Ferrite LTCC-Based Monolithic SIW Phased Antenna Array

In this paper, we present a novel configuration for realizing monolithic substrate integrated waveguide (SIW)-based phased antenna arrays using Ferrite low-temperature cofired ceramic (LTCC) technology. Unlike the current common schemes for realizing SIW phased arrays that rely on surface-mount component (p-i-n diodes, etc.) for controlling the phase of the individual antenna elements, here the phase is tuned by biasing of the ferrite filling of the SIW. This approach eliminates the need for mounting of any additional RF components and enables seamless monolithic integration of phase shifters and antennas in SIW technology. As a proof of concept, a two-element slotted SIW-based phased array is designed, fabricated, and measured. The prototype exhibits a gain of 4.9 dBi at 13.2 GHz and a maximum $E$ -plane beam-scanning of ±28° using external windings for biasing the phase shifters. Moreover, the array can achieve a maximum beam-scanning of ±19° when biased with small windings that are embedded in the package. This demonstration marks the first time a fully monolithic SIW-based phased array is realized in Ferrite LTCC technology and paves the way for future larger size implementations.

A Highly Integrated Independently Tunable Triple-Band Patch Antenna

A highly integrated tunable triple-band patch antenna is designed and fabricated. Two U-slots are cut in the same radiating patch to achieve triple-band performance. While the antenna miniaturization is obtained by loading one patch edge with metalized vias, theory of characteristic modes is adopted to explain the U-slots scaling. The antenna radiating patch size is only 0.1λ 0 × 0.17λ 0 . The operating frequencies can be independently tuned after properly inserting three varactor diodes into the radiating structure. The radiation patterns have similar unidirectional shapes with high stability of the resonant frequencies during the entire tuning of each band. Good agreement between simulation and measurement results is obtained. The antenna covers the following bands: 2.07-2.6 GHz, 2.86-3.57 GHz, and 4.59-5.39 GHz. The measured peak gains and efficiencies are 2.72 dBi and 62.6%, 2.76 dBi and 63.3%, and 2.87 dBi and 66.8%, respectively. Size reduction, multiband function, and independent tuning of three operating bands using only one antenna layer and one RF feedline are combined together to realize a compact and practical antenna.

A Compact Ka-Band Active Integrated Antenna With a GaAs Amplifier in a Ceramic Package

This letter presents the design of a Ka-band active integrated antenna in package (AIAiP). A monolithic microwave integrated circuit amplifier based on the GaAs process and a compact patch antenna based on the printed circuit board process are implemented, respectively. Then, the amplifier and antenna are assembled together in a specified package using the wire-bond process. Thus, compared to the traditional solutions, the transmission loss and the size of the proposed AIAiP are significantly reduced. Furthermore, the influence of the bonding wire and the package is taken into account in the design of the amplifier and the antenna, respectively. A good agreement between the simulation and measurement results can be observed. The proposed AIAiP occupies a compact size of 7 × 7 mm2. Meanwhile, it achieves −10-dB impedance bandwidth from 33.4 to 37.2 GHz and a peak gain of 18.9 dBi at 35 GHz. Additionally, the impact of the package size on the antenna performance has been demonstrated for future AIA designers.

Selection of Optimal Beam Forming Algorithm for Mobile Ad Hoc Networks

Ad hoc networks have drawn considerable attentions of researchers for the last few years. Various applications of ad hoc networks have been reported in the literatures including disaster management, battle field, environmental management, healthcare, and smart grid. Ad hoc networks have some limitations namely short operating life, unreliability, scalability, delay, high interference, and scarce resources. In order to overcome these limitations, numerous researches have been carried out. Smart antenna integration is one of them. It has been shown in the literatures that smart antenna can improve network’s capacity, increase network lifetime, reduce delay, and improve scalability by directing antenna radiation pattern in a desired direction. But, producing a desired antenna radiation pattern is not a simple task for resource constraint ad hoc networks. A careful selection of beam forming algorithm is required. In this paper we show that smart antenna system, consisting of circular microstrip antennas and arranged in a linear arrangement, is the most suitable choice for ad hoc network. We compare a number of smart antenna algorithms in this paper under different noisy conditions. We show that the Least Square Constant Modulus (LSCM) and Least Constant Modulus (LCM) algorithms outperform other algorithms in terms of directivity and minimized side lobes.

Highly Sensitive Reentrant Cavity-Microstrip Patch Antenna Integrated Wireless Passive Pressure Sensor for High Temperature Applications

A novel reentrant cavity-microstrip patch antenna integrated wireless passive pressure sensor was proposed in this paper for high temperature applications. The reentrant cavity was analyzed from aspects of distributed model and equivalent lumped circuit model, on the basis of which an optimal sensor structure integrated with a rectangular microstrip patch antenna was proposed to better transmit/receive wireless signals. In this paper, the proposed sensor was fabricated with high temperature resistant alumina ceramic and silver metalization with weld sealing, and it was measured in a hermetic metal tank with nitrogen pressure loading. It was verified that the sensor was highly sensitive, keeping stable performance up to 300 kPa with an average sensitivity of 981.8 kHz/kPa at temperature 25°C, while, for high temperature measurement, the sensor can operate properly under pressure of 60–120 kPa in the temperature range of 25–300°C with maximum pressure sensitivity of 179.2 kHz/kPa. In practical application, the proposed sensor is used in a method called table lookup with a maximum error of 5.78%.

Integration of a 'proton antenna' facilitates transport activity of the monocarboxylate transporter MCT4.

Monocarboxylate transporters (MCTs) mediate the proton-coupled transport of high-energy metabolites like lactate and pyruvate and are expressed in nearly every mammalian tissue. We have shown previously that transport activity of MCT4 is enhanced by carbonic anhydrase II (CAII), which has been suggested to function as a 'proton antenna' for the transporter. In the present study, we tested whether creation of an endogenous proton antenna by introduction of a cluster of histidine residues into the C-terminal tail of MCT4 (MCT4-6xHis) could facilitate MCT4 transport activity when heterologously expressed in Xenopus oocytes. Our results show that integration of six histidines into the C-terminal tail does indeed increase transport activity of MCT4 to the same extent as did coexpression of MCT4-WT with CAII. Transport activity of MCT4-6xHis could be further enhanced by coexpression with extracellular CAIV, but not with intracellular CAII. Injection of an antibody against the histidine cluster into MCT4-expressing oocytes decreased transport activity of MCT4-6xHis, while leaving activity of MCT4-WT unaltered. Taken together, these findings suggest that transport activity of the proton-coupled monocarboxylate transporter MCT4 can be facilitated by integration of an endogenous proton antenna into the transporter's C-terminal tail.

Diced and grounded broadband bow‐tie antenna with tuning stub for resonant tunnelling diode terahertz oscillators

Radiation from antennas integrated with indium phosphide (InP)-based resonant tunnelling diode (RTD) oscillators is mainly through the substrate because of the effects of the large dielectric constant. Therefore, hemispherical lenses are used to extract the signal from the backside of the substrate. In this study the authors present a broadband bow-tie slot antenna with a tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to the air-side direction. Antenna integration with RTD oscillators is described in this study as well. Two-port bow-tie slot antennas were designed and characterised and showed the suitability of integration with power combining RTD oscillator circuits which are based on mutual coupling. The antennas were fabricated using electron beam lithography on a semi-insulating InP substrate. Simulated and measured bandwidth almost extends the entire frequency range 230–325 GHz. Simulations shows air-side radiation pattern and antenna gain of around 11 dB at 280 GHz. Simulations also show that the antenna may be fed with a 50-Ω or 30-Ω feed line, i.e. suitable feed lines, without compromising its performance which may prove beneficial for optimum loading of RTD oscillators.

Theory of Optical Leaky-Wave Antenna Integrated in a Ring Resonator for Radiation Control

The integration of a leaky-wave antenna with a ring resonator is presented based on the leaky-wave theory and integrated waveguide models. The device consists of a ring resonator fed by a directional coupler, where the ring resonator path includes a segment that is turned into a leaky-wave antenna. We devise an analytical model of the guided wave propagation along a directional coupler and the ring resonator path, including the antenna and non-radiating segments. The resonator integration provides two main advantages: 1) the high-quality factor resonance ensures effective control of radiation intensity by controlling the resonance conditions and 2) the efficient radiation from a leaky-wave antenna even when its length is much smaller than the propagation length of the leaky wave. The tradeoffs regarding the quality factor of resonance and the antenna efficiency of such a design are reported in terms of the coupler parameters, leaky-wave constant, and radiation length. Finally, a CMOS-compatible OLWA suitable for the ring resonator integration is designed where silicon is utilized as the waveguide material for a possible electronic control of radiation intensity. The simulation results together with the analytical model show that slight variations in the leaky wave's propagation constant, realized through excitation of excess carriers in the Si domain, is sufficient to control the far-field radiation modulation with high extinction ratio.

Integrated NFC power source for zero on-board power in fluorescent paper-based lateral flow immunoassays

A lab-on-chip vehicle was explored combining RF near field communication (NFC) harvested power and light sources for paper-based lateral flow immunoassay systems (LFIA) with quantum dots (QD) as fluorophores. Such a vehicle has potential applications in point-of-care systems requiring high sensitivity while also being low-cost, disposable and easy to use. Micro-LEDs which provided the excitation source for the test line of a QD-LFIA were surface mounted on plastic substrates using a printed hybrid electronics approach for the fabrication of power harvesting NFC antenna, chip assembly and electronics integration with the LFIA strip. The LFIA is a rotavirus assay kit with Au nanoparticles into which QDs emitting at 655 nm were also incorporated. A digital camera was used for detecting the fluorescence from QDs and the reflected signal from Au NPs. The signals were compared using grayscale analysis. The NFC-powered LED light source integrated with the QD-LFIA demonstrated ~9× higher sensitivity compared to conventional Au-NP based assays. Such an integrated system can be potentially mass manufactured using roll-to-roll processing making the device cost effective, as well as having high sensitivity.

Review on Isolation Techniques in MIMO Antenna Systems

Objectives: Presently, wireless applications are quickly moving towards multiple input multiple output configuration, thereby the quest for integration of many antennas in the user’s equipment enhanced. A MIMO Antenna is used as a reason of enhancing the capacity of the channel without the need of additional power or frequency band. It requires many antennas set up in the transmitter with less coupling between them. Methods/Statistical Analysis: Hence, for an effective MIMO antenna system mutual coupling between the antennas should be low. Various MIMO antenna designs have been reported by antenna researchers for wireless application. The main design challenge in MIMO antennas is to attain high isolation amid the antenna elements. This paper reviews various isolation techniques proposed in the recent years. A detailed analysis on the design issues such as antenna miniaturization, integration issues, antenna coupling and isolation enhancement techniques are presented. Findings: among the isolation methods discussed better isolation is achieved using meta materials, decoupling networks and defected ground structures. Application: MIMO antenna systems find application in portable devices, automotive applications, handheld devices, personal digital assistant etc.

High-Efficiency Self-Oscillating Active Integrated Antenna Using Metamaterial Resonators and Its Application to Multicarrier Radio Frequency Identification Systems

A self-oscillating active integrated antenna with very high dc-to-radio frequency (RF) conversion efficiency is proposed and validated with the aid of metamaterial resonators. The key innovation is the new integration scheme which allows an independent control of the resonators used in the feedback oscillator and the radiating element in the integrated antenna. The metamaterial resonator, featuring a high quality factor for good oscillation performances, is applied to excite the dipole-mode ground radiation with good radiation efficiency at the same time. The design principle is introduced; the circuit and antenna parameters including the loop gain, oscillation output power, phase noise, effective isotropic radiated power, and radiation patterns are investigated in detail. Its application to multicarrier RF identification systems as a low-cost continuous-wave source is supported by quantitative measurement results.

On-Chip Monolithic Integrated Antennas Using CMOS Ground Supply Planes

Monolithic integrated antennas have the potential to provide new functionality to wireless systems on chip like higher integrability, fast and easy-to-implement chip-to-chip communication, and sensor miniaturization. There are two major issues with on-chip antenna integration: 1) the chip area dedicated to the antenna should be as small as possible; and 2) the standard CMOS silicon substrate has high dielectric losses at microwave frequencies, which reduces dramatically the antenna efficiency. This paper summarizes the implementation of on-chip antennas manufactured in the CMOS ground supply plane on low-loss substrates as a possible solution for efficient antenna integration.

On-Chip Antenna Integration for Millimeter-Wave Single-Chip FMCW Radar, Providing High Efficiency and Isolation

A complete functional 60-GHz BiCMOS single-chip millimeter-wave frequency-modulated continuous wave (FMCW) radar with on-chip integrated antennas is designed, realized, and experimentally validated. The chip is configured with one transmitting and two receiving antennas. A high antenna efficiency and isolation between the transmitting and receiving antennas is achieved by using a cavity-backed on-chip monopole and by optimizing the package environment. Surface-wave losses and back radiation are reduced, and a high antenna gain is obtained with small ripples in the antenna pattern by implementing special structures on the PCB of the integrated circuit package. The experimental results from the single-chip radar show that the on-chip antennas provide a gain of 2 dBi with very low back radiation. The realized antennas achieve an impedance bandwidth of more than 50% with a corresponding simulated efficiency of 45%. In addition, the proposed approach suppresses surface waves and meets the specific FMCW radar requirements, such as a more than 25-dB isolation between the transmitting and receiving antennas.

Small-Size LTE/WWAN Two-Strip Monopole Exciter Antenna Integration With Metal Covers

A novel small-size LTE/WWAN two-strip monopole exciter antenna integration with metal covers for ultrabook computer applications is presented. The monopole exciter antenna is placed in the hinge slot between metal covers and hinges. By integrating the monopole exciter antenna with the metal covers and hinges, not only several modes of the monopole structure but those of the hinge slot are also excited to cover the desired eight-band LTE/WWAN operation (LTE700/GSM850/900 and GSM1800/ 1900/UMTS/LTE2300/2500 bands). The exciter antenna comprises a feeding strip and a folded strip to form a two-strip monopole structure. The proposed exciter antenna can be integrated with the surrounding metal planes (metal covers) to enhance the operating bandwidth to cover LTE/WWAN band with good radiation efficiency. The exciter antenna has a simple two-strip structure that is easy to be fabricated on a 0.8-mm thin FR4 substrate with a small area of only $25 \times 8$ mm2. Over the lower and upper bands, the antenna efficiencies are about 65%–88% and 55%–78%, respectively.